Handbook for Civil Aviation Medical Examiners...become more liberal to the point now that the...

Handbookfor Civil Aviation

Medical Examiners

http://www.tc.gc.ca/CivilAviation/Cam/menu.htm

Également disponible en français sous le titre de :Guide pour les médecins examinateurs de l’aviation civile

TP 13312E*TP13312E*

(03/2004)

01_i Pages 2004-03-05 11:37 AM –i

Catalogue No. T52-103/2004EISBN 0-662-35838-4

RDIMS Locator No. 701877

© Her Majesty the Queen in Right of Canada, as represented by the Minister of Transport, 2004

All rights reserved. No part of this information (publication or product) may be reproduced, or transmitted in anyform or by any means, electronic, mechanical, photocopying, recording or otherwise, or stored in a retrievalsystem, without prior written permission of the Minister of Public Works and Government Services, Ottawa,Ontario, Canada K1A 0S5 or at [email protected].

The information in this publication is to be considered solely as a guide and should not be quoted as or consideredto be a legal authority. It may become obsolete in whole or in part at any time without notice.

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HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

RECORD OF AMENDMENT

RECORD OF AMENDMENT

No. Date of amendment Date inserted Inserted by

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TABLE OF CONTENTS

TABLE OF CONTENTS

FOREWORD

TABS

SECTION 1

SECTION 2

NEUROLOGY

CARDIOVASCULAR

DIABETES

ASTHMA

OTHER POLICIES

CONTACTS

NOTEThis handbook has been produced at Civil Aviation Medicine Headquarters in Ottawa.

Any errors, omissions or suggestions should be forwarded to:

Dr. James M. WallaceCivil Aviation Medicine Branch (AARG)

Transport Canada330 Sparks Street

Place de Ville, Tower “C”, Room 617Ottawa, Ontario

K1A 0N8

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FORWORD

The history of medical standards in civil aviationdates back to just after World War I when theInternational Commission on Air Navigation (ICAN)was established following the Paris Air Conventionof 1919. This organization was set up to establishrules and regulations for the safe conduct of civilaviation. ICAN established a medical sub-commission which set about producing the first evermedical standards for civil aircrew which wereextremely strict. In 1944, towards the end of WorldWar II, the International Civil Aviation Organization(ICAO), an agency of the United Nations, wasformed to carry on the work of ICAN, which hadceased to exist during World War II. Over the years,the international standards and those of Canada havebecome more liberal to the point now that themajority of the population over the age of 16, if theyso wished, would pass aviation medical certificationexaminations.

In Canada, the regulations pertaining to medicalrequirements are contained in Part 404 of theCanadian Aviation Regulations (CARs) while theactual medical standards are in Part 424 of theCanadian Aviation Regulations. Both Part 404 andPart 424 form part of this Handbook. CAR 424.05permits the Civil Aviation Medicine Branch toexercise flexibility in medical certification of pilotsand air traffic controllers who technically do not meetthe standard, but for whom a c c redited medicalconclusion is such that the failure to meet thestandard is such that the exercise of the privilege ofthe licence is not likely to affect air safety.

Over the years, guidelines have been produced in themajor areas which cause problems with aeromedicalcertification, namely neurology, cardiology anddiabetes. A copy of these guidelines is available inthis Handbook.

In your role as a Civil Aviation Medical Examiner(CAME), you are usually the only person whophysically examines the pilot or ATC and makes arecommendation for medical certification. You aretherefore the most important link in the chain ofsafety in the medical certification process. Whileperforming your CAME function, you are acting asan agent of the Minister of Transport, so TransportCanada will indemnify you for any litigation thatmay come from your aviation medical examinationactivity which is conducted in good faith. Recentchanges in the medical certification process, and

delegation of validation authority to the examinerhave not resulted in increasing the exposure tolitigation, and will therefore not result in increases tomalpractice insurance premiums for CAMEs.

Accompanying this book is a video outlining thechanges that have taken place in the medicalcertification process, and showing you how tocomplete the Medical Examination Report form (26-0010) completely. The medical handbook part ofthis document is not a text on aviation medicine, it ismerely an introduction to the subject and covers thebasic facts that you must have to understand themedical problems associated with flight. It will helpyou deal with many of the questions you may beasked and hopefully will encourage you to furtherstudy the subject. More detailed information on thesubject of aviation medicine can be obtained from thefollowing books:

Aviation Medicine – J. Ernsting, A. Nicholson andD. Rainford, Third Edition (1999), Butterworth –Heinemann.

Fundamentals of Aerospace Medicine – R. DeHartand J. Davis, Third Edition (2002), Williams andWilkins.

Clinical Aviation Medicine – R. Raymond, ThirdEdition (2000), Castle Connolly Graduate MedicalPublishing, LLC.

Civil Aviation Medicine Branch has developed anInternet website which will be used more and morefor the dissemination of information between theBranch and CAMEs. Those of you who have Internetaccess are welcome to browse the website and submityour comments. The address is:

http://www.tc.gc.ca/CivilAviation/Cam/menu.htm

Civil Aviation Medical Standards

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SECTION 1

SECTION 1

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SECTION 1

Table of ContentsSECTION 1

Page

Civil Aviation Organization and Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–1

CAM HQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–1CAM Regional Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–1Figure 1 – TC Aviation Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–1 Licensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2Civil Aviation Medical Examiners (CAMEs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2Termination of Appointments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2

The Medical Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–3

Figure 2 – Medical Examination Requirement Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–4Civil Aviation Medical Examination Report Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–5Completing the Medical Examination Report Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–7Chart 1 – Body Mass Index (BMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–9Figure 3 – Vision Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–10Figure 4 – Medical Certificate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–12

APPENDIX 1 – The Maddox Rod Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–14

APPENDIX 2 – Colour Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–15

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HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS 1–1

SECTION 1

The Civil Aviation Medicine (CAM) Branch is one ofseveral branches of the Directorate General of CivilAviation in Transport Canada. The Director of CivilAviation Medicine reports to the Director General ofCivil Aviation.

CAM Headquarters

CAM Headquarters is located in the Tr a n s p o r tCanada Building, 330 Sparks Street, Tower “C”,Place de Ville, Ottawa, K1A 0N8.

The mandate of CAM is to provide medical adviceand assistance in setting out physical standards forCivil Aviation personnel; to advise in all problemsconnected with the health of travellers by air.

The mission is to ensure aircrew and air trafficc o n t rollers are medically fit, to close gaps inscientific knowledge of Canadian aviation medicine,to promote health and safety in the field of aviationand to prevent aircraft accidents due to medicallyrelated human factors.

CAM Regional Offices

There are currently four Regional offices acrossCanada located in Montreal, Toronto, Edmonton, andVancouver. The Edmonton, Toronto, and Montrealoffices are under the direction of a Regional AviationMedical Officer (RAMO) while the office inVancouver is staffed by an Aviation Medical Officer.The RAMOs are responsible for the selection and

Civil Aviation Medical BranchOrganization and Administration

Figure 1

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1–2 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

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training of CAMEs, for reviewing the medicalexamination reports of pilots, flight engineers, and airtraffic controllers, and for approving an appropriatemedical category for aviation personnel. CAM doesnot issue licences, it issues Medical Certificates(MCs). Licensing is a responsibility of TransportCanada, General Aviation. As a CAME, you maynow renew MCs, for the full validity period, oflicensed aviation personnel for renewal medicalexaminations only. Initial medical reports, categoryupgrades and removal or addition of restrictions to aMC must be sent to the RAMO for assessment.

Licensing

All pilots, flight engineers, and air traffic controllersmust be licensed by Transport Canada, GeneralAviation Branch. After completing such requirementsas flight training, written examinations, and flighttests, an applicant is granted a licence by thedepartment. Licences do not have a validity period,but must be validated by a current MC which has alimited duration. There are four medical categoriesshown on the medical certificate, each of whichvalidates a different type of licence. The types, therequired medical categories and the validity periodsof the licences are shown in the Medical ExaminationRequirements Table. (Figure 2)

Civil Aviation Medical Examiners (CAMEs)

CAMEs are appointed on the basis of need, by theRAMO or AMO on behalf of the Minister ofTransport. Interested physicians apply to the CAMoffice in their region and are interviewed by theRAMO prior to appointment. If accepted as adesignated CAME, they must await the receipt of theofficial letter of appointment before performing anyaviation medical examinations. The letter ofappointment will be sent together with a full CAMEauthority package, including this Handbook, aCAME numbered stamp and a wall certificate. AllCAMEs who are newly appointed will be required toattend a training seminar at the earliest opportunity,and then no less than once every four years.

Aviation medical examinations may only be carriedout by a CAME. In the case of pilots residingoverseas, the examination may be carried out by amedical examiner approved by the licensingauthority of a contracting state of the InternationalCivil Aviation Organization (ICAO). Appointment ofCAMEs in areas outside Canada is at the discretionof the Senior Consultant, Operations, Policy andStandards, of Civil Aviation Medicine Branch or theDirector of Civil Aviation Medicine.

All CAME appointments are valid for a period offour years, renewable upon the recommendation ofthe RAMO. Re-appointment will depend on thequality and timeliness of reports, demonstratedcontinuing interest in aviation medicine, andfeedback from the aviation community. There mustalso be a continuing requirement for services in theCAME’s designated geographic area.

Termination of Appointments

It is rare for a CAME appointment to be terminated.If there are significant problems with the quality ofthe medical information being submitted, the RAMOwill contact the CAME and take whatever remedialaction is necessary to assist in solving the problem.

Appointments may be terminated for any of thefollowing reasons:

1. Frequent or continual low quality professionalperformance.

2. Failure to provide reasonably prompt service.

3. Unethical conduct.

4. Loss or suspension of medical licence.

5. Prolonged inability to provide service due to illhealth or disability.

6. Change of geographic location.

7. Voluntary relinquishment of the appointment bya CAME.

CAMEs may, at any time, request that theirappointment be terminated.

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SECTION 1

The Medical Examination

It is your responsibility to interview and perform acomplete examination on all applicants for aviationmedical certification. You may be the only physicianin the normal course of events who has talked to thepilot and had a “hands-on” opportunity to form animpression. Although the Medical ExaminationReport form (MER) may look similar to others youhave completed for insurance examinations, yourinput here is much more valuable and is of immediateimportance.

Since pilots and air traffic controllers are at risk oflosing their medical certificate, and in some casestheir employment, each time they present themselvesfor a medical, they naturally find aviation medicalexaminations threatening. For this reason, werecommend that you and your staff do all in yourpower to put the applicant at ease prior to theexamination. This examination is always stressfuland often becomes more stressful as aviationpersonnel grow older.

Aviation personnel, although not basically dishonest,may not volunteer information which may affect theirmedical certification. They will, however, respond todirect questions and will sometimes give you muchmore information than you expect if you convincethem that your prime interest is keeping them atwork. Sometimes they have problems that may affecttheir medical certification that they would like todiscuss with someone of good will. Of particularimportance in the interview is any suggestion ofsubstance abuse, mental instability, lack of insight orinappropriate reactions. You have an opportunity todecide whether this is the type of person with whomyou would fly or to whom you would entrust yourfamily. Remember, that the next time you climb onboard as a passenger this may be your Captain!

Normally when you deal with patients you areconcerned with their immediate health. In aviation amore important concept is that of sudden and/orsubtle incapacitation. This may arise from suchdiverse stresses as the pain of acute renal colic or thesubtle loss of judgment that results from an occultbrain tumour. A pilot in trouble in the air cannot stopand pull over to the side of the road until thesymptoms pass! A point to bear in mind is that inannual medicals we are chiefly concerned with theshort term, that is, the validity period of the medicalcertificate.

The medical examination is recorded on the form,Medical Examination Report 26-0010 (MER), theoriginal of which should be sent to the Regionaloffice. The MER is available in both English andFrench and is periodically updated. The effective dateis located in the lower left corner of the form as(1999-03). Blank forms are available upon requestfrom the Regional offices.

The MER is reviewed in the Regional office. If theMER is not complete or if there are errors oromissions, it will be returned for correction. Theoriginal form should then be corrected and returnedto the Regional office.

The next few pages will help you to fill out the MERand indicate the type of answers required. There isalso an Appendix on the visual examination. Thisseems to be the most difficult part of the examinationand so befits greater explanation. Hopefully all elsewill be clear after your first seminar but, if in doubt,your RAMO is no further away than your telephone(See contact numbers –Toll free).

A useful reference is the ICAO Manual of AviationM e d i c i n e produced by the International CivilAviation Organization. Copies of this can be obtainedby writing to the following address:

(The manual is currently being revised.)

Document Sales UnitInternational Civil Aviation Organization999 University StreetMontreal, QuebecH3C 5H7Canadawww.icao.int

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Figure 2

Medical Examination Requirements

Licence orPermit Type

MedicalCategory Age Medical Report Audiogram Age Electrocardiogram

Airline TransportSenior CommercialCommercial

(Validates all othercategories)

1 Under40

Over40

Within twelve monthsof issue orrevalidation

Within six months ofissue or revalidation

At firstexamination then at55 years old

Under30

30-40

Over40

At first examination

At first examinationand every two yearsthereafter

At first examinationand every yearthereafter

NOTE: The holder of Medical Category 1 shall be considered fit for any permit or licence for its respective duration ofvalidity unless otherwise specified

Flight NavigatorFlight EngineerAir Traffic Controller

2 Under40

Over40

Within two years ofissue or revalidation

Within twelve monthsof issue or revalidation

At first examinationthen at 55 years old

Under30

30-40

Over40


At first examinationand every two yearsthereafter

At first examinationand every yearthereafter

* Student PilotPrivate PilotGyroplane PilotFree Balloon Pilot

3 Under40

Over40

Within five years ofissue or revalidation

Within two years ofissue or revalidation

(If clinicallyindicated)

Under40

Over40

N.A.

At first examinationand every four yearsthereafter

Ultra Light Instructor

Glider Instructor

4 Within five years ofissue or revalidation


Under40

Over40

N.A.

At first examinationand every five yearsthereafter

Glider PilotUltra Light Pilot

4 Medical Declaration(Full MER only ifclinically indicated)


N.A.

Recreational PilotStudent Pilot

4 Medical Declaration orForm 26-0297countersigned by aphysician


Under40

40-50

Over50

N.A.


At first examinationand every four yearsthereafter

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SECTION 1

Completing the Medical Examination ReportThis section deals specifically with the completion ofthe form.

BLOCK LETTERS OR TYPING SHOULD BE USED

PART A

REGION AND HQ FILE NUMBER

– These blocks will be completed by the Region.

TYPE OF LICENCE/PERMIT DESIRED

– Indicate any of the types listed in Fig. 2.

AVIATION LICENCE/PERMIT HELD

– Indicate any of the types listed in Fig. 2. Initialapplicants should have “NIL” indicated here.

PERMIT/LICENCE NUMBER

– Enter the applicant’s permit/licence number ifavailable.

TELEPHONE NUMBER

– Indicate numbers with area codes, Fax, e-mail.

NAME, FAMILY NAME AND FORMER SURNAME

– Complete legal names should be indicated here.Initials and nicknames cause confusion.

ADDRESS, CITY\COUNTRY, PROVINCE, POSTAL CODE

– Full addresses are required. Abbreviations shouldnot be used.

COUNTRY OF RESIDENCE

– Self explanatory.DATE OF BIRTH – Self explanatory.

PLACE OF BIRTH (COUNTRY)

– Indicate the country only.

MALE/FEMALE

– Self explanatory.

CITIZEN OF

– Indicate citizenship.

EDUCATION

– Indicate highest level achieved e.g. Grade 12 (orUniversity).

OCCUPATION, EMPLOYER


PILOT FLIGHT TIME

– This can be very important. A hiatus or suddenchange in flying time patterns may indicate anillness/injury which has not been revealed. Grandtotal is all the flying time since the applicantstarted flying.

HAVE YOU HAD AN AIRCRAFT ACCIDENT ...?

– Accident data is not kept on the Department ofTransport pilot files. We rely on the informationyou provide. If the pilot answers yes, note whetherthere was a medical cause or any medical sequelaein the “Review of Systems” part of the form.

HAVE YOU CONSULTED A PHYSICIAN? REASON?


AERONAUTICAL PUBLICATIONS

– Indicate the language preferred by the applicant.

PRIMARY TYPE OF FLYING INTENDED

– Recreation includes all non-business related flying.Business includes all business, commercial andmilitary flying.

DATE OF LAST CIVIL AVIATION MEDICAL EXAMINATION

– Indicate date and place if known.

DATE OF LAST ECG, CHEST X-RAY AND AUDIOGRAM

– Show the complete date if known.

NOTE: If you are examining the applicant for thefirst time ask for proof of identity,preferably photo ID!

PART B

Family History

This section is included to identify people at higherrisk for genetic or familial diseases. Any “yes”answers require comment in the blank spaceprovided. There is also a block here in which you canrecord cardiovascular risk factors.

Review of Systems

The functional inquiry is the basis for any goodmedical examination. This part should be completedby you. The questions, of course, are simply a guideand are not all inclusive. A positive response shouldbe elaborated in the space below or, if there isinsufficient space, on an attached sheet.

Statement of Applicant

This is a legal declaration that the applicant hassupplied complete and accurate information. It releasesthe medical information on the MER and other reportsto CAM and Transport Canada. The applicant mustread, date and sign the declaration and the signaturemust be witnessed. The applicant should be aware thatit is an offence under the Aeronautics Act to knowinglymake a false declaration.

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PART D

Civil Aviation Medical Examiner’sRecommendation

Most of this is self-explanatory. It is possible for acandidate who is an air traffic controller to have twocategories such as 2 and 3, as the candidate could bealso eligible for private pilot medical certification.The “remarks” area is for any observation orrecommendation you wish to make. Part D should besigned at the end of the complete examination andmust bear your personal CAME stamp.

PART C

General Physical Examination

This section should be completed by you althoughsome portions, such as the height, weight and bloodpressure may be completed by your staff. They mustbe trained and supervised, and appropriately‘delegated’ in accordance with the policy of yourmedical licensing authority. It is preferable that youperform the entire examination.

HEIGHT AND WEIGHT

– Use metric figures.

BLOOD PRESSURE

– This should be recorded while the applicant issitting, using a cuff of appropriate size. If a non-standard cuff is used this should be recorded. Thediastolic blood pressure to be recorded is thedisappearance of the sound.

IDENTIFYING MARKS

– Note any surgical scars, tattoos or other marks.These may be useful for identification in aircraftaccidents.

NUTRITION

– There are no Transport Canada standards fordesirable or maximum weights of individuals.Body Mass Index (BMI) is a useful indicator of ahealthy weight. (See Chart 1.)

– BMI = Weight in Kg divided by the height in metres2

– The ideal BMI range is 20-25

NOSE AND THROAT

– The examination should be directed to the presenceof any condition which would impair respiratoryfunctions or pressure equalization during flight.

EAR DRUMS

– Examine for any pathology, perforations and forthe adequacy of pressure equalization. Pressureequalization should be assessed by observation ofthe drum during a Valsalva maneuver. Vestibularfunction should be normal.

RESPIRATORY SYSTEM

– Self-explanatory.

CARDIOVASCULAR

– This should include an assessment of the peripheralcirculation as well as the heart. A careful noteshould be made of any murmurs.

ABDOMEN INCLUDING HERNIA

– Rectal examination is not mandatory but, inkeeping with good medical practice, isrecommended for males over age 45. A nassessment of the inguinal areas for hernia isnecessary, since inguinal hernias are not consideredsafe in the aviation environment.

GENITOURINARY

– Self explanatory. Pelvic examination is notrequired.

LOCOMOTOR

– Pilot applicants should be assessed for the ability toundertake flight operations in normal andemergency situations. In the case of amputation orparaplegia, special practical tests will be ordered bythe RAMO to determine the applicant’s suitabilityfor flight.

NEUROLOGICAL

– A screening examination with assessment ofreflexes is required.

MENTAL STATUS

– This is an overall assessment of the psychologicalsuitability for the aircrew of air traffic controllerlicence. A brief comment regarding an applicant’smental stability would be appreciated in the“Remarks” section.

INTEGUMENT

– skin etc.

Visual Examination

Note: An excellent outline of an aviation visualexamination can be seen on the video, “TheVision Examination for Civil Av i a t i o nMedical Examiners” available from CAMHeadquarters.

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SECTION 1

This should include examination of the external eyeand direct or indirect ophthalmoscopy. Particularattention should be directed to the cornea to detectcontact lenses and/or the scars of surgical proceduresto correct refractive errors such as PRK and LASIK.Cycloplegic examination is not routinely required.

VISUAL FIELDS

- Assessment by confrontation is adequate.

Distant Vision Testing

The Transport Canada standards for vision aresummarized in Fig. 3. Distant vision should be testedusing Landolt Rings, a chart of Snellen letters orother similar opotypes situated at an optical distance

of 6 meters using either an eye lane or an approvedvision testing instrument. Where an eye lane is used,the test chart must be illuminated to a levelequivalent to that provided by a 100 watt lightbulbplaced 120 centimeters in front of, and slightly abovethe chart with the light shielded from the applicant.The examination room should be darkened with theexception of the chart.

The uncorrected vision should be tested initially ineach eye separately, and then in both eyes. Squintingis not permitted. After the uncorrected vision istested the corrected vision should be tested in thesame manner.

Chart 1

BODY MASS INDEX (BMI)

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Contact Lens Wearers – It is necessary to test theuncorrected vision in the initial examination withoutthe use of lenses or provide a contact lens report froman eye care professional. They should also be testedwith backup glasses prior to putting their lenses inplace and the results noted beside the distant visiontesting blocks.

If a contact lens wearer cannot remove his/her lensesat the initial examination, he/she should be requiredto return. It is not necessary to repeat examination toremove the contact lenses.

In initial applicants if the uncorrected vision is 6/60or less the refractive error must be recorded in thespace provided.

Be sure to note whether contact lenses were wornduring the examination and whether you recommendan eye specialist’s examination.

Near Vision

Near vision should be tested with the Faculty ofOphthalmologists Reading Type ‘N’ charts orequivalent. Vision in each eye separately should betested without and then with correction. Use good“over the shoulder” illumination of the card andavoid reflections and glare. Note that the standarddoes not require the near vision correction to meetTC Standards in each eye separately.

Ocular Muscle Balance

Ocular muscle balance can be tested with the covertest, the Maddox rod or an approved vision tester.Report the results of the cover test in the spaceprovided. The Maddox rod results should be noted inthe appropriate spaces. Checking the orthophoria boxmeans that there is no deviation and the other spacescan be left blank. Any deviations should be noted inthe esophoria, exophoria and hyper phoria boxes.

Figure 3

VISION STANDARDS

Distant Vision In each eye separately, equal or better than

Category 1 6/9 (20/30) Corrected or uncorrected in each eye.6/6 (20/20) both eyes

Category 2 Same as Category 1.

Category 3 6/9 (20/30) or6/12 (20/40) Corrected or uncorrected.No less than 6/60 (20/200) uncorrected.

Category 4 No less than 6/9 (20/30) in the better eye.

Near Vision

Categories 1, 2 and 3 N5 at 30 – 50 cm.

Category 4 No standard.

Ocular Muscle Balance

Categories 1, 2 and 3 Exophoria and Esophoria: maximum 6 prism dioptres.Hyperphoria: 1 prism dioptre.

Category 4 No standard.

N.B. Vision Testing machines such as the Titmus Vision Tester, Keystone Orthoscope or Telebinocular,Bausch & Lomb Orthorator may be used.

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SECTION 1

Maddox Rod Test – This is described in detail inAppendix 1 and on the aviation vision video. Theresults should be recorded in the number of dioptresof esophoria, etc. The use of this instrument isdemonstrated in the video “The Vision Examinationfor Aviation Medical Examiners”

Cover Test – The purpose of this test is to determinewhether manifest strabismus is present, or whetherthere is any tendency of the eyes to deviate when thetwo eyes are dissociated. The examiner stands infront of the candidate who is told to fix his eyes on asmall target such as a small examining light. Anoccluder card is then placed in front of one eye andthe other eye checked for movement. If there is nonethe card is removed and the covered eye examined tosee whether it has remained fixed or whether it hasmoved medially or laterally and has to be re-fixated.The test is then repeated with the other eye covered.

If the candidate is orthophoric no movement of theeyes will take place. If there is esophoria one eye willmove in and then re-fixate when the occluder isremoved. In exophoria the opposite is true. It shouldbe noted that less than 10% of individuals areorthophoric!

Colour Perception

Colour perception should be tested at each aviationmedical examination because various eye diseasesmay cause a change or deterioration. Colour visionmay be tested with any of the standard pseudo-isochromatic test plate sets noted in Appendix 2.Appropriate lighting must be provided for testing. Ifa special colour balanced light source is not used,daylight is best for screening. Be wary of fluorescentor incandescent lights which may cause inaccuratereadings. The type of plates (Pseudo-isochromatic,Ishihara etc.), the number of plates in the set (versusthe number that should be used for testing) and thenumber of errors should be noted.

An applicant failing colour plate testing may have acolour lantern or a Farnsworth D-15 Hue testperformed. These tests are available at a number oflocations across the country or CAM regional offices.

Note: The colour lantern test is not acceptable forinitial air traffic controller applicants, whomust pass the plates or a Farnsworth D-15Hue test.

Hearing Examination

This should be tested with the whispered voice. Theapplicant must be able to hear and understand at adistance greater than 2 metres. Testing with screeningaudioscope is acceptable. Abnormalities noted on thescreening test should prompt testing by pure toneaudiometry. Candidates for Category 1 or 2 medicalcertification will require a pure tone audiogram at theinitial examination.

Urinalysis

Routine dip-stick testing of the urine for glucose isrequired at each aviation medical examination.Microscopic examination is only required whereclinically indicated.

Other tests

– Self-explanatory.

Renewing a Medical Certificate

If an applicant who has a licence meets all themedical standards in CAR 424 you may renewhis/her Medical Certificate (MC) by stamping,signing and dating one of the renewal boxes on theMC. Return the ‘renewed’ MC to the applicant andmark the FIT box on the MER form. You cannot grantadditional privileges. For example, if an applicantwith a restriction such as “Valid only when wearingrequired glasses” presents for medical certificationwith contact lenses, you can only extend the presentprivileges, not give authorization for him/her to usecontact lenses when flying. This must be done byCAM. In the same way you cannot give authorizationfor an upgrade from one medical category to another.

Initial applicants do not have a MC so you cannotgrant them a medical category and can only mark theDEFERRED box, indicating “initial applicant” underthe remarks area.

If an applicant does not present a MC for signatureyou cannot renew, but only mark DEFER andindicate “no MC available” under the remarks area.

If an applicant wishes to upgrade from a Category 3to Category 1, complete the examination, arrange foran ECG and audiogram to be submitted with theMER, and renew the existing Cat 3 MC for the fullperiod. If the applicant meets the Category 1 standardthen a new multi sign off Category 1 MC will be sentto him\her by Transport Canada.

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Figure 4

MEDICAL CERTIFICATE

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SECTION 1

HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS 13

If renewal has been granted, mark “yes” in the “Wasa renewal assigned” block on the MER. If it was notgranted mark “no”, check the DEFERRED box, andindicate the reason in the space underneath. Alsoindicate whether further examination isrecommended and whether a separate confidentialreport is being submitted.

If you feel that the applicant is fit, make sure that youput the date of renewal on the renewal box as thisrelates to the validity period – An undated renewalmakes the MC invalid!

Note: If you do not believe an applicant is fit forthe category requested, DO NOT RENEWTHE MC, mark the DEFERRED box in part“D” of the MER, and add your comments,either in the remarks section or in aconfidential report.

The examination form and all additional test resultsare then forwarded to the RAMO. A copy should beretained in your office for a minimum of six months,but it is wise to retain the copies indefinitely as withany medical record, particularly in the presentclimate of medico-legal litigation.

Special Renewal

A small number of licensed personnel will have beenissued with a MC that has been endorsed over therenewal boxes “Not valid for CAME renewal”.

In these cases, send in the medical examinationreport and any other reports/tests that have beenrequested. Mark the “depressed” box in Part “D”.The applicant will be issued with a new MC at eachexamination.

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APPENDIX 1

THE MADDOX ROD TESTThis test is used to uncover latent squints (phorias).The test may be performed with a handframe, avision tester or a trial frame but the principle in all isthe same. If a candidate is given two dissimilartargets to view at the same time, the stimulus tofusion is absent and phorias are uncovered.

The Maddox rod is a disc of red glass in which aremolded grooves. When a distant spot of light isviewed with the disc in front of one eye, a red linewill be seen by the eye covered with the lens, whilsta spot of light will be seen with the other eye. Theline will be at right angles to the grooves to that whenthese are horizontal the line will appear vertical. Acandidate with no latent deviation will see thecoloured line pass through the spot of light(orthophoria), whereas a candidate with latent squintwill see the light source to one side of the line.

The Maddox rod with rotating prism is held in frontof the right eye and the candidate is asked to look ata point source of light 6m (20 ft.) away in a darkenedroom. Both eyes must be open and squinting shouldbe avoided. The candidate is asked which side of theline the dot is seen. If it is to his right, esophoria ispresent and if to the left, exophoria. The candidate isthen asked to “put the line on the light” by adjustingthe rotating prism. The examiner reads off the degreeof phoria from the scale on the device.

The test is repeated with the disc turned to thevertical position. The light will now be seen eitherabove or below the line and may be adjusted by thecandidate in the same way. If the red line is above thelight there is left hyperphoria, if below the light, righthyperphoria.

If the candidate sees several lines, there are aberrantlight sources and, if they cannot be suppressed, thecorrect line can be indicated by turning the spot lighton and off several times. Some candidates are awarethat the line should pass through the spot and may tryto hide their phorias. This should be suspected if acandidate with an abnormal cover test sees the linedirectly through the light. In this case the lens can beadjusted so the dot and the line do not coincide andthe candidate’s response should be noted.

Definitions

Orthophoria – No tendency to deviate.

Esophoria – Tendency of the eye to turn in.

Exophoria – Tendency of the eye to turn out.

Hyperphoria – Tendency of one eye to turn up orthe other eye to turn down.

Demonstrations of the Maddox rod Test may be seenon the video The Vision Examination for AviationMedical Examiners.

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APPENDIX 2

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COLOUR VISIONIn the retina there are two groups of photosensitivecells, the rods and the cones. The cones, concentratedin the central retina, are colour sensitive. T h e ycontain three different pigments. One is sensitive tored, another to green and a third to blue. Congenitalcolour deficiencies are caused either by the absenceof one of the pigments or by an alteration in thepigment which leads to distortion of colours. Peoplelacking or deficient in the red pigment are known asProtans, the green pigment Deutans and the bluepigment Tritans. The latter problem is unimportantand unusual.

Normal people are trichromats. Those who have onlytwo pigments are dichromats and, according to themissing pigment, are referred to as protanopes,deuteranopes and tritanopes. There are also groups oftrichromats whose pigments, although present, areanomalous. According to the pigment therefore theyare protanomalous, deuteranomalous ortritanomalous (trichromats). Approximately 8.5% ofthe male population and 0.4% of the femalepopulation have colour vision defects. About 4.6% ofall males are deuteranomalous trichromats and theother 3.4% are evenly distributed amongst theprotanomalous trichromats, deuteranopes andprotanopes with a frequency of about 1% each.

Pseudoisochromatic plate tests differentiate betweenpeople with normal colour vision and those withdefective colour vision of types which might interferewith aviation safety. These plates should be viewed

by the applicant in natural daylight. The applicantshould not be allowed to wear sunglasses or “X-Chrom” lenses. Each plate should be heldapproximately 75 cm. in front of the applicant withthe plate perpendicular to the visual line. A delay ofup to three seconds is allowed for the answer to eachplate and it is permissible to repeat a plate if thepatient has a negative response. If two responses aregiven, the second should be recorded. The platesshould be given in a random order so they cannot bememorized. The number of acceptable incorrectresponses to each type of plate is shown below.Colour vision testing should be carried out from timeto time as it also varies in eye diseases and may be anearly method of detecting such problems.

Applicants who fail the plates may be tested with acolour vision lantern. A number of these are availablein each region and information is available throughthe RAMO’s office. The Farnsworth D-15 Hue test isalso acceptable.

Note: The colour lantern test is not acceptable forinitial air traffic controller applicants, whomust pass the plates or a Farnsworth D-15Hue test.

TYPE EDITION TESTED ERRORS ALLOWED

American Optical (1965 Ed.) 18 1-18 3

American Optical HRR 20 1-6 0

Ishihara 16 1-8 1

Ishihara 24 1-15 2

Ishihara 38 1-21 3

Ishihara (concise) 14 1-14 Special explanation with plates

Keystone Orthoscope ® All 0

Keystone Telebinocular ® All 0

Titmus All 0

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SECTION 2

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Table of ContentsSECTION 2

Page

The Atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1

Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1Divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1Ozone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1Atmospheric Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1Figure 5 – Properties of the Standard Atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–2Cosmic Radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–3

Hypoxia and Hyperventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–4

Respiratory Physiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–4

Hemoglobin Dissociation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–4Figure 6 – Oxyhemoglobin Dissociation Curves for Human Blood . . . . . . . . . . . . . . . . . . . . . . 2–5Hyperventilation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–6Pressurization and Depressurization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–6Figure 7 – Cabin Pressurization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–6Figure 8 – Times of Useful Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–7For Those of Mathematical Bent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–7

Dysbarisms and Altitude Sickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–8

Barotitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–8Other Barotraumas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–8Intestinal Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–8Inflatable Medical Aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–8

Decompression Sickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–9

Bubble Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–9Symptoms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–9Neurological Effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–9Provocative Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–9Scuba Diving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–10

Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–11

G Axes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–11Physiological Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–11Figure 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–11Positive Gz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–12Negative Gz and Jolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–12Traverse and Lateral G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–12

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Orientation and Disorientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–13

Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–13The Vestubular System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–13Figure 10 – View of the Right Labyrinth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–13Proprioception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–14Visual Illusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–14Autokinesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–14Vectional Illusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–14Vestibular Illusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–14Figure 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–15The Leans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–15Figure 12 – The Action of the Cupula During Prolonged Rotation . . . . . . . . . . . . . . . . . . . . . . 2–16Prolonged Turns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–16The Graveyard Spiral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–16The Coreolis Phenomenon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–17Types of Illusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–17

Motion Sickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–18

Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–18Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–18


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THE ATMOSPHERE

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SECTION 2

The earth’s atmosphere surrounds it like a gaseousblanket, kept in place by the gravitational field. Thedepth of the atmosphere varies from time to time,being greater in the summer than in the winter andgreater at the lower latitudes than at the higherlatitudes. Heat radiating from the sun causesatmospheric gases to expand into space and it is theinteraction between this force and gravity that setsthe limits of the atmosphere.

Composition

The atmosphere is a mixture of various gases. Thethree of greatest importance are Nitrogen (78.09%),Oxygen (20.95%) and Carbon Dioxide (0.03%). Theremainder is made up of rare gases. The compositionof the atmosphere is remarkably constant up toapproximately 300,000 feet although at high altitudesthe distance between gas molecules becomesprogressively greater and collisions between particlesbecomes rarer. There is a variable amount of watervapour in the atmosphere up to about 30,000 ft. andin the lower altitudes there are also solid pollutantswhich provide nuclei for condensation.

Divisions

We live in the troposphere which means “the area ofchange”. In the troposphere the temperaturedecreases with increasing altitude at a rate of 1.98°Cor 3°F/1000 ft. The troposphere extends up to 60,000ft. over the equator but only to about 30,000 ft. overthe poles. At that altitude it becomes the tropopausewhere the air temperature is fairly constant between -50 and -55°C. Above the tropopause, which is about30,000 ft. deep, is the stratosphere which extends toabout 50 miles (80 kms.). There is no weather in thestratosphere and indeed there is little weather above35,000 ft. One of the joys of flying is that on thedullest day one can break out into bright sunlight ifyou climb high enough.

Ozone

Within the stratosphere lies the ozonosphere at 18-30miles (30-50 km.) above the earth. The temperaturehere becomes warmer (about 35°C) due to heatreleased when ozone is converted to oxygen by solarradiation. Only in the last decade has the importanceof the ozone layer become apparent to us all. In thestratosphere oxygen absorbs ultraviolet (UV)radiation of 2,000 Å. And 3 molecules of oxygen aretransformed into 2 molecules of ozone. If unchecked

this reaction would produce a huge amount of ozone,however ozone in turn absorbs ultraviolet light from2,100 to 2,900 Å. and is converted back to oxygen.This balanced reaction results in the almost totalabsorption of harmful ultraviolet radiation. Recentlyit has been found that the ozone layer is beingdestroyed, particularly over the poles, by earth’spollutants. This may give rise to the increasingpenetration of UV light causing an increase in skincancer, cataracts and other health problems.

Ozone is a blue, unstable, toxic gas. T h econcentration at ground level is 0.03 parts per million(ppm) by volume but this increases rapidly above40,000 ft. to become a maximum of 10 parts permillion by volume at 100,000 ft. Modern supersonicaircraft fly at altitudes where this can be a problem.In the human, acute exposure for two hours tobetween 0.6 and 0.8 ppm. reduces the diffusingcapacity of the lungs and slightly reduces vitalcapacity and forced expiratory volume. Fortunatelythese effects are not permanent unless there iscontinual exposure. Ozone impairs night vision inman and in human cell cultures can induce chromaticbreakages identical to those produced by x-rays.Fortunately ozone is thermally unstable and isdecomposed promptly to oxygen at 400°C. Thistemperature is reached by the Concorde’s airconditioning compressor circuit during climb andcruise, neutralizing what could otherwise be asignificant problem.

Atmospheric Pressure

Atmospheric pressure is the weight of the gasessurrounding the earth. It is a function of height,density and the force of gravity. At ground level it isrecorded by meteorologists as 101.32 kilopascals butmany people prefer the older 14.7 lbs. per sq. inch or,as used in most medical calculations, 760 mmHg.Atmospheric pressure decreases with altitude and at18,000 ft. it is halved (380 mmHg) and at 33,000 ft.quartered. It should be noted that the changes aresmall and gradual compared to the changes observedgoing down in water. Here atmospheric pressuredoubles at 33 ft! As will be noted later this is a pointof importance when dealing with fliers who are alsoscuba divers.

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Figure 5

PROPERTIES OF THE STANDARD ATMOSPHERE

The properties of the standard atmosphere showing the variation in the height of the tropopause.

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Cosmic Radiation

The atmosphere is affected by both galactic and solarionizing radiation. The former is a predictable, lowdensity flux of high energy particles from outside thesolar system. Most of these are deflected by theearth’s magnetic field although the protection isgreater in the equatorial regions than at the poles.There is also some protection by the solar inter-planetary magnetic field and by the stratosphericabsorption of low energy particles. Measurements ofthis type of radiation have been taken from highaltitude aircraft. Fortunately the annual dose isrelatively low in constantly exposed air crew. Solarradiation is of lower energy but its production may beintense and is generally unpredictable although itappears to reach a peak about every 11 years. Theearth is well shielded by its atmosphere but the dosemay be significant in prolonged high altitude or spaceflight. It’s most commonly observed effect isinterference with radio and other forms ofcommunication equipment at the time of solar flares.Space flight will lead to more precise measurementsof its long term effects.

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SECTION 2

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HYPOXIA AND HYPERVENTILATION



The hazards of high altitude became evident as soonas men set out in balloons, although the dangers hadbeen suspected by missionaries in mountainous areaslong before. In 1590 the Jesuit Priest Acosta noted“... I am convinced that the element of the air is inthis place so thin and so delicate that it is notproportioned to human breathing which requiresextensive and more temperate air”.

In 1862 Glaisher and Coxwell made an ascent byballoon to almost 29,000 ft. and became unconscious.Fortunately one of them, his hands frozen, was ableto raise his head sufficiently to grab the valve cord ofthe balloon in his teeth before passing out, thusreleasing hydrogen and bringing the balloon backdown. Paul Bert in the late 1860’s built an altitudechamber and reached the conclusion that, regardlessof barometric pressure, air could not supply life whenthe partial pressure of oxygen reached 45 mm. Hg. InApril of 1875 Crocé-Spinelli, Sivel and Tissandiermade the first flight in a balloon using oxygenalthough Bert had warned them the supply was fartoo small. Only one of the three survived, the othertwo dying of hypoxia.

Respiratory Physiology

To maintain life, oxygen has to be inhaled, diffusedacross the alveolar-capillary membrane, carried byhemoglobin to the tissues and then transferred to theindividual cells for aerobic metabolism. Dalton’sLaw states that the partial pressure of a gas in a gasmixture is equal to the pressure which the gas wouldexert if it alone occupied the space taken up by themixture. Each of the gas components in the mixturetherefore exerts pressure proportional to the fractionwhich it represents. Oxygen, being present as 20.9%,(21%) of the gases in our atmosphere exerts a partialpressure of 160 mm. Hg in dry air at sea level.However this changes when it is inspired. In thenasopharynx air is exposed to water vapor andbecomes saturated at body temperature (37°C). Watervapour pressure is 47 mm. Hg. In the tracheatherefore the partial pressure of oxygen will be (760- 47) x 0.21 or approximately 150 mm. Hg. Passingfrom the trachea to the alveolus, oxygen becomesmixed with carbon dioxide. It is also diffusing intothe tissues from the respiratory bronchioles down, soby the time the alveolus is reached, the partialpressure of oxygen is much lower. The partialpressure of carbon dioxide is about 40 mm. Hg so thealveolar partial pressure of oxygen at ground level,

when the respiratory quotient is taken into account, is103 mm. Hg (For those mathematically inclinedrelevant formulas are given at the end of thischapter). This steadily dropping partial pressure isknown as the respiratory cascade.

The diffusion of oxygen (and of carbon dioxide in theopposite direction) takes place at the level of therespiratory bronchioles and below. The majority ofthe diffusion takes place at the alveolus which isvirtually surrounded by capillary blood. The area ofthe alveolar-capillary interface is astonishingly large,between 90 and 100 sq. metres. If spread out thealveoli would cover a double tennis court.

D i ffusion at the alveolus takes place along thepressure gradient with most of the oxygen beingpicked up by hemoglobin for transfer to the tissues.The rate of diffusion of a gas is proportional to itssolubility and to the pressure gradient. Carbondioxide, being more soluble than oxygen, diffuses ata faster rate. In the tissues the pressure of oxygenfalls with increasing distance from the capillary, withthe lowest level being found midway between twocapillaries. If the partial pressure of oxygen fallsbelow 3 mm. Hg in the tissues anaerobic metabolismdevelops. Under normal conditions a rise in PC02and the formation of tissue lactic acid causescapillaries to dilate. In muscle the number of opencapillaries can increase by 200 times but in the brainmost of the capillaries are open, even at rest, so evenin the face of imminent hypoxia the number ofcerebral capillaries can increase only by a factor offour. This is why hypoxia affects the brain first.

Hemoglobin Dissociation

Oxy-hemoglobin (Hb02) dissociation describes anS-shaped curve (See Figure 6) when saturation isplotted against oxygen partial pressures. T h echaracteristics of this curve are important. Down to apartial pressure of 60 mm., saturation remains above90%. Below this point saturation drops off rapidlybeing less than 80% by the time the partial pressurehas dropped to 45 mm. The sharp drop-off of thecurve enables oxy-hemoglobin to unload rapidly inthe relatively hypoxic tissues and equally allowsreduced Hb to pick up oxygen rapidly at normaldiffusion gradients. Under hypoxic conditions lacticacid is formed in the tissues causing a relativeacidosis which moves the curve to the right,increasing the uptake and release of oxygen. In

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alkalosis, as in hyperventilation, the curve movesleft, lessening tissue availability. (Fig.6)

At 10,000 ft. the PAO2 has reached 60 mm., which isthe beginning of the rapid drop in hemoglobinsaturation. Above this altitude significant tissuehypoxia develops and it is for this reason that oxygenis required while flying above 10,000 ft. If the pilot isbreathing 100% oxygen however the partial pressureof oxygen at any level will be much higher. Thecritical level of 60 mm. at the alveolus for examplewill not be reached until 40,000 ft. This is referred toas an “equivalent oxygen level”.

Hypoxia

Hypoxia is an insidious killer. There is a tendency foreuphoria to develop while motor skills and reasoningabilities deteriorate. The result is that in many casesthe pilot may become seriously hypoxic withoutappreciating that there is a problem. To the observertachypnea, cyanosis, mental confusion and loss ofmuscle coordination are obvious. To the pilothowever, the only symptoms may be slight dyspnea,dizziness, fatigue, decreasing vision and finally lossof muscular control. Night vision can be impaired atas low as 5000 ft. Tolerance to hypoxia varies fromindividual to individual and from time to time.Tolerance can be increased by continual exposure tohigh altitudes and varies with the level of thehemoglobin and the oxygen carrying capacity of theblood. It is decreased by fatigue, cold and poorphysical conditioning. Even at 5,000 ft. night visionis decreased.

Types

Hypoxia is generally divided into four types.

Hypoxic hypoxia is due to a decrease in the oxygenavailable to the body such as typically occurs withaltitude.

Hypemic hypoxia is caused by a reduction in theoxygen carrying capacity of the blood for any reason.It also occurs when hemoglobin is saturated by gasesfor which it has a higher affinity, the most commonof which is carbon monoxide. This is not onlyproduced by exhaust leaks into the cockpit but alsoby cigarette smoking. Carbon monoxide is a productof incomplete combustion and may be present atlevels of 6-8% in the blood of a heavy smoker andsuch individuals may become significantly hypoxicat levels below 10,000 ft.

Stagnant hypoxia is a less common problem causedby a reduction in total cardiac output, pooling of theblood or restriction of blood flow. Heart failure,shock, continuous positive pressure breathing and G-forces in flight can create stagnant hypoxia. Localstagnant hypoxia can occur with tight and restrictiveclothing or, in the cerebral circulation, in associationwith vasoconstriction due to respiratory alkalosisprovoked by hyperventilation.

Histotoxic hypoxia refers to poisoning of therespiratory cytochrome system by chemicals such ascyanide or carbon monoxide but it can also be causedby the effects of alcohol. Needless to say a pilot inpoor physical condition, recovering from a hangoverand smoking while in flight can quickly become anunfortunate statistic!

Gravity and Atelectasis

In the seated position the lungs, due to the pull ofgravity, are stretched at the apices and condensed atthe bases. At the same time, the blood supply is leastat the apices and greatest at the bases. Thus in thearea where the alveolar ventilation is best, perfusionis least and at the bases the opposite is true. Only inthe mid section of the lung is there an idealventilation – perfusion ratio. Under positive G, thesituation is exaggerated and if it is of long duration increws breathing oxygen, rapid absorption from thealveoli tends to cause basilar atelectasis.

Figure 6

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HYPERVENTILATION

Hyperventilation may be described as a respiratoryrate excessive for the body’s oxygen requirements. Itmay be voluntary or involuntary and can occur inrelation to many different activities. In the pilot themost common precipitating causes are anxiety, fear,excessive concentration on a flight procedure and asa reaction to pain or illness. Hyperventilation may beobvious, as in the case of children preparing tocompete in underwater swimming, or it may becovert as for example when the respiratory rateincreases from a required 12 per minute to anexcessive 15 per minute and remains elevated for aprolonged time.

Whatever the cause the results are the same. Carbondioxide, the most potent stimulus to respiration, isblown off in excessive amounts. The PACO2 fallsand respiratory alkalosis develops. The cerebralvessels become constricted and subjectively the pilotoften notices a feeling of dizziness, a coldness andtingling around the lips and a feeling as though therewas a band around the head. Nausea may be present.Peripherally there is vasodilatation and stimulation ofsensory nerves causing a sensation of pins andneedles in the hands and in the feet. Ifhyperventilation continues carpopedal spasmdevelops and the subject may become unconsciousand develop frank tetany. With the breath held thecarbon dioxide levels build up once more and thesymptoms disappear in reverse order.

Obviously such a chain of events can lead to anaccident. This has been documented in someincidents in young fighter pilots or untrained privatepilots who have inadvertently flown into bad weatherand have kept the microphone button depressed,broadcasting their breath patterns up to their finalmoment. Hyperventilation is often suspected inunexplained accidents. If one considers thesymptoms of hypoxia and hyperventilation it will beseen that they are very similar. As it is imperative inthe air that no mistake be made, the treatment forboth is to breathe 100% oxygen and to reduce the rateand depth of respiration.

Pressurization and Depressurization

Although it is usually in military pilots that problemsarise with hypoxia at levels above 30,000 ft., it mustbe remembered that more and more commercialaircraft are now cruising at extreme altitudes andflight above 40,000 ft. is common. The Concorde, forexample, cruises above 60,000 ft. Cabinpressurization in these aircraft ensures that the partial

pressure of oxygen is adequate and it is rare for thecabin pressure to be above 7,000 ft. (See Fig. 7).However, it is wise to remember that passengers withchronic lung diseases or serious anemia, particularlythose who are smokers, may be significantly hypoxiceven at this altitude.

More dangerous however is the situation whichdevelops when cabin pressure suddenly fails, usuallydue to the loss of a window or door. The result israpid decompression with a sudden increase in thecabin altitude to match the ambient altitude. Inaircraft such as the Concorde the windows have beenmade particularly small to lessen this effect but inolder aircraft more serious problems have occurred.The immediate effect of decompression is a loudnoise, condensation of water vapour causing a mistand a shower of dust and small particles. T h etemperature falls dramatically. The resultant cabinpressure may actually fall below that of the ambientpressure due to “aerodynamic suck”. This refers tothe Venturi effect created by the speed of the aircraftthrough the air.

The initial hazard to aircraft safety is hypoxia. Thecrew are unlikely to be wearing oxygen masks at thetime of the incident and, if the final cabin altitude ishigh, the time of useful consciousness may be veryshort (see Figure 8). It may actually be lower thanwould be anticipated because of the sudden escape ofexpanding gas from the lungs due to the reducedambient pressure. This causes reversal of the oxygendiffusion gradient across the alveolar membrane andoxygen passes back into the lung from the blood. At35,000 ft. the time of useful consciousness is

Figure 7

CABIN PRESSURIZATION

AmbientAltitudein feet

Cessna152

Boeing727

Boeing777

Boeing747

80,00040,00035,00022,50015,000

SL

––––

15,000SL

––

5,500SLSLSL

–6,5004,500

SLSLSL

–7,7004,700

SLSLSL

SL = Sea Level

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generally quoted as 30 – 60 seconds but at altitudesof above 40,000 ft. this may be reduced to 12 – 15seconds, the normal circulation time. Airlines makeprovision for this eventually by providing pilots with“quick-donning” oxygen masks, which can bedonned in 5 seconds or less.

FOR THOSE OF MATHEMATICAL BENTIn Dry Air:

PIO2 = AP x FIO2 where PIO2 is the partial pressureof oxygen, AP is atmospheric pressure and FIO2 isthe fraction of oxygen in the inspired air.

In the Trachea:

PIO2 = (AP – WVP) x FIO2 where WVP is watervapour pressure. At sea level this is (760 – 47) x 0.21= 150 mmHg.

In the Alveolus:

PAO2 = PIO2 – PAC O2 [FIO2+ (1 – FIO2/R)] wherePACO2 is the partial pressure of carbon dioxide andR is the respiratory quotient.

Therefore at sea level PAO2 = 150 – 40 [0.21 + (1 –0.21/0.82)] = 103 mmHg.

Or at 18,000 ft. = (380 - 47) x 0.21 - 30 (0.21 + 1 –0.21/0.82) = 35 mmHg.

The respiratory quotient (R) on a pure carbohydratediet is 1.00, on a protein diet 0.81 and on an animalfat diet 0.71. On a balanced diet of carbohydrate,protein and fat, R is generally about 0.83.

Figure 8

TIMES OF USEFUL CONSCIOUSNESS(Effective performance time)

Altitude Conscious time

20,000

25,000

30,000

35,000

40,000

45,000

50,000+

5 – 12 minutes

2 – 3 minutes

45 – 75 seconds

30 – 60 seconds

10 – 30 seconds

12 – 15 seconds

12 or less seconds

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DYSBARISMS AND ALTITUDE SICKNESS



We have already commented on the decrease inatmospheric pressure which occurs with altitude.Boyle’s Law states that, at constant temperature, thevolume of a gas varies inversely with the pressure. Ifthe pressure of gas is halved, its volume is doubled.Application of this simple law to the closed bodycavities quickly indicates where problems are likelyto occur.

Barotitis

By far the most common problems are with themiddle ear. It resembles a box, closed by a flexiblediaphram at one end and drained by the Eustachiantube narrow tube at the other. The eustachian tubehowever is not rigid or symmetrical throughout itslength and becomes slit-like at its outlet in thenasopharnyx. On ascent expanding trapped airusually escapes easily and the only thing noticed is aperiodic “popping” due to movements of the drum aspressure equalizes. On descent however equalizationof pressure through the slit-like outlet is much moredifficult and a negative pressure can build up in themiddle ear. This leads to a decrease in hearing and topain. The ear can be cleared by opening and closingthe mouth, thus activating the tensor tympani muscleand dilating the tube, or by inflation by a Valsalvamaneuver. In an U.R.I. or other pathology of thenasopharynx, congestion of the outlet makes clearingmore difficult or even impossible. The pressure in themiddle ear on descent may then become so lowrelative to the outside pressure that exudation andhemorrhage may take place and ultimately theeardrum may burst. Excessive valsalva maneuvershowever may force bacteria into the middle ear,leading to infection.

When an ear blocks and cannot be cleared by theusual maneuvers, the best way to deal with thesituation is to reascend and start a slower descent.This is not always possible. During World War II thepilots of vertical diving Stukas had constant earproblems and their flight surgeons solved these byperiodically incising the drums! Nowadays this is notrecommended! A particular problem occurs whenpilots flying at high altitude on oxygen retire to sleepsoon after landing. The middle ear is full of solubleoxygen (rather than inert introgen) which is absorbedduring sleep. On awakening they have earache due tothe indrawn drums. This is called “oxygen ear”.

Other Barotraumas

Other air spaces are equally affected. The nasalsinuses are a common source of pain as may bepoorly filled teeth if the filling has not been carefullyinserted and a gas space remains below it. Thesevarious symptoms are referred to as “barotraumas”and toothache of this type is known as“barodontalgia”. The best approach to theseconditions is knowledge and prevention. Fortunatelymost professional pilots are well aware of theproblems and avoid flying when they are congested.

Intestinal Gas

A common irritating, embarrassing and potentiallyserious problem is gas in the bowel. This expandsrapidly as might be expected and, if it cannot bepassed, may lead to severe pain. Chewing gum, airswallowing, carbonated drinks and beer (in thepassenger) all add to the gas, as do various gasproducing foods. Passengers with ostomy bags orvarious types of bowel obstruction are particularlylikely to have problems.

Inflatable Medical Aids

Boyle’s Law must be kept in mind if you are involvedin the transport by air of patients requiring cuffedtubes of any type or if casts or pneumatic dressingsare being used. Cuffs should be inflated with saline(or water) rather than air before the trip.

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DECOMPRESSION SICKNESS

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The “Bends” or “Caisson disease” has beenrecognized since 1841 in association with “hard hat”divers or men working under pressurized conditions.By the end of WWI the possibility of decompressionsickness in aviators was predicted and once highaltitude balloon flights were undertaken theprediction was fulfilled. The cause of decompressionsickness is the formation of gas bubbles in the bodyand the physical law was described by Henry.Henry’s Law states that the quantity of gas that goesinto solution at a given temperature is dependentupon its solubility characteristics and is proportionalto the partial pressure of that gas over the surface ofthe liquid. Hence as the pressure falls, the amount ofgas which can be held in solution is reduced.

Bubble Formation

The dominant gas in the atmosphere we breathe isnitrogen. It is inert and the body is saturated with it atground level. During rapid ascent the reduction ofbarometric pressure creates a condition whereby theinert gas tension in the tissues is greater than theexternal barometric pressure. This condition is calledsuper-saturation. At this point, in association withbubble nuclei produced by muscle shear forces orturbulent blood flow, bubbles of nitrogen can beformed in the tissues and in the body fluids. It is thesebubbles which give rise to decompression sickness.

Symptoms

The symptoms of decompression sickness aredescribed as the four “C’s”. These are Creeps,Cramps, Chokes and Collapse”. “C re e p s” is anunpleasant sensation as though tiny insects aremoving underneath the skin. This “formication” isbelieved to be caused by the formation of tinybubbles. “Cramps”, usually described as “Bends”,are manifested by pain which tends to be localized inand around the large joints of the body. Smaller jointsmay be affected and it is not uncommon to firstnotice the symptoms in joints which have previouslybeen injured. The pain is deep and aching in characterand varies from mild to severe. It is made worse bymovement of the joints and is sometimes improvedby pressure on the area. “Chokes” are rare, occurringin less than 2% of cases. It is a much more seriousdisorder caused by multiple pulmonary gas emboli.The subject complains of substernal chest pain,dyspnea and a dry, non-productive cough. He/shefeels ill and usually appears anxious and distressed. If

altitude is maintained “C o l l a p s e” will inevitablyoccur. The treatment is immediate descent which isgenerally effective.

Neurological Effects

Neurological decompression sickness is the mostdangerous form and often has a very seriousprognosis. It may be responsible for permanentneurological deficits particularly if hyperbarictreatment is not immediately available. It occurs in 5-7% of cases of decompression sickness, and, inaltitude cases not relieved by returning to groundlevel, the central nervous system is involved 35-50%of the time. In the aviator brain injuries, althoughuncommon, are most frequent. In divers the spinalcord type is most frequent. The reason for thisvariance is not known.

In the brain type visual disturbances (scotoma, tunnelvision, diplopia etc.) are common together withheadache and confusion. Physical signs are spottyand diffuse, both motor and sensory. The signs maybe thought to be hysterical but collapse may occur. Inthe spinal cord the most common onset is ofnumbness or paraesthesia in the feet. This tends tospread upwards in the cord with ascending weaknessand/or paralysis. A complete transverse spinal cordlesion may occur as bubbles obstruct the bloodsupply and infarct the cord.

Fortunately serious decompression sickness isuncommon in commercial aviation. Generally thealtitude threshold is above 18,000 ft. although itrarely occurs below 25,000 ft. Above 26,000 ft. it ismore common. It is much more often seen thereforein high altitude military pilots whose cockpitpressurization profiles are lower than those incommercial aircraft.

Provocative Factors

There are various factors which affect it. T h eincidence increases with age, there being a threefoldincrease between the 19–25 year old and the 40–45year old age groups. Nitrogen is well dissolved in fat,so obesity is a factor. It is probably more common inwomen than men. It is more common with exercise ataltitude, with rapid ascents, with re-exposure toaltitude at frequent intervals and at low temperatures.The after effects of alcohol and intercurrent infectionboth increase the susceptibility.

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Scuba Diving

It is important to keep in mind the relationshipbetween SCUBA diving and decompression sicknessin aviators. SCUBA divers use compressed air intheir tanks and are often exposed to two or moreatmospheres of pressure, supersaturating the tissues.If they fly within twelve hours of emerging fromdiving at standard depths, decompression sicknesshas been recorded at altitudes as low as 10,000 ft.Where they have been diving at depths which requiredecompression stops on the way to the surface, theyshould not fly for a minimum of 48 hours. Althoughserious problems are uncommon, it is necessary to beaware of the danger to recognize it, particularly withneurological symptoms.

Occasionally a medical emergency results when adiver ascends to the surface too rapidly, causing abubble formation. In such cases the diver must be re-exposed to a greater pressure as quickly as possibleand then brought back to the surface. Sometimes thediver is too ill to undertake another dive and must betransported to a hyperbaric chamber for treatment asquickly as possible. Pilots transporting suchindividuals should be cautioned that increases inaltitude will worsen the patient’s condition. Ifpressurized aircraft are not available, flights shouldbe made at the lowest safe altitude. Recompressiontreatment tables are outlined in textbooks of Divingmedicine.

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ACCELERATION

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Doctors often feel that an understanding ofacceleration (G) and the effects of gravity (g) areonly of importance to aerobatic or high performanceaircraft pilots. This is a mistake. Because we arenormally terrestrial creatures, bonding to the earthhas taught us that gravity exerts a downward pull. Inan aircraft however, G-forces are often upward oroutward and as they are associated with changes inboth acceleration and direction, what is experiencedis a resultant force. It is these forces and their effectson the vestibular organs which give rise to ourrecognition of position in space. In the review oforientation the importance of this will be explained.

G Axes

Speed is the rate of movement of a body whilevelocity is a vectorial quantity made up of both speedand direction. Acceleration (G) is a change invelocity either in direction or in magnitude. It isdescribed in three axes in relation to the body, x, yand z. Each axis is described as positive (+) ornegative (–) according to an international convention.

Considerable confusion can arise if a clear distinctionis not made between the applied acceleration and theresultant inertial force as these, by definition, alwaysact in diametrically opposite directions. Thus aheadward acceleration tends to displace tissues suchas viscera and the eyes, footward and the resultantforce is termed positive G, +Gz. (See Fig. 9).

Physiological Effects

The physiological effects of G vary with itsmagnitude, duration and axis of application and aremodified by the area over which it is applied and thesite. Tolerance to acceleration varies from day to dayand is modified by body build, muscular tone andexperience. It is decreased by poor health orconditioning, fatigue, hypoxia and alcohol. It can beincreased by continued exposure and education.Pilots exposed to heavy G loads soon learn to use amodified Valsalva manoeuvre with controlledbreathing and muscle contraction to increase theirtolerance (the M1 manoeuvre) . G-suits mechanicallyincrease resistance to positive Gz by exerting

Figure 9

Direction ofAcceleration

Direction of Resultant Physiological and VernacularStandard Terminology

Descriptors

Headward Head to Foot Positive GEyeballs down +Gz

Footward Foot to Head Negative GEyeballs up –Gz

Forward Chest to Back Transverse A-PGSupine GEyeballs in

+Gx

Backward Back to Chest Transverse P-AGProne GEyeballs out

–Gx

To the Right Right to Left side Left lateral GEyeballs left +Gy

To the Left Left to Right side Right lateral GEyeballs right

–Gy

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pressure on the lower limbs and the abdomen toprevent pooling of blood. Unfortunately there is nomechanical device to counteract negative Gz.

Positive Gz

Positive Gz forces the pilot into the seat, draining theblood towards the lower part of the body. A 150 lb.pilot exposed to +4G has a weight equivalent to 600lbs. This interferes with muscular movement, aircraftcontrol and the ability to change position or to escapein an emergency. As G comes on and blood is drainedfrom the head, the first symptom is visual. Thenormal intra-optic arterial pressure is 20/25 mm. ofHg. and under loads as low as 2-3G peripheral visionis decreased due to retinal anemia. This leads to“grey-out”, a condition in which peripheral vision isprogressively lost and central vision begins to lose itsacuity. As the G load increases the retinal arterialflow is further reduced until “black-out” occurs. Atthis point, although vision is absent, the cerebralblood flow is often maintained and the pilot mayremain conscious. At 5-6G however most pilotsbecome unconscious unless they are protected. Thisis referred to as G-LOC. (G-Loss of consciousness).When the G load is reduced, consciousness will beregained although there is often a brief period ofconfusion before full awareness is reached. If the Gload is high and the onset is of short duration, G-LOCcan occur without warning. This has been determinedas the cause of several accidents in high performanceaircraft.

Negative Gz and Jolt

Negative Gz, acting from the foot to the head, ispoorly tolerated by the body and in most cases thethreshold is below –5 Gz. As might be expected thevisual symptom is “red-out” as blood is forcedtowards the head and into the retinal arterioles.Excessive –Gz leads to hemorrhages into theconjunctiva and ultimately into the brain.

A special form of G is known as “jolt”. Jolt is the rateof change of acceleration. It is descriptively used inrelation to short, sharp accelerations. This type ofshock can give rise to serious spinal injuries and mustbe minimized in the design of ejection seats.

Brief alternating positive and negative Gz forces areexperienced in turbulence and may be a seriousproblem when flying light aircraft in hot weather orflying high speed aircraft at low levels. G-forces notonly interfere with precise flying but are also a potentsource of fatigue.

Transverse and Lateral G

Tolerance to transverse G (Gx) is much higher. It isfor this reason that the astronauts in the early vehicleswere placed in a recumbent position during lift-off.Forces as high as +60 Gx have been experienced overshort intervals without injury. However, G interfereswith both lung inflation and respiratory movementsand forces greater than +20 Gx quickly lead tobreathing difficulties. –Gx is less well tolerated. Gyis not of great enough amplitude to cause problems inconsciousness and is not a problem with modern dayaircraft. It does come into account however in VTOLaircraft such as the Harrier which is able to “VIFF”(Vector in forward flight) sideways to evade attack.At present, head restraint is the only problemexperienced with Gy.

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ORIENTATION AND DISORIENTATION

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To the earth bound individual, orientation meansbeing aware of one’s body position relative to theearth. Gravity acts towards the centre of the earth andis recognized as down. The aviator however lives ina different world, a world in which proprioceptivesenses may give rise to false information. At the topof a loop for example, where centrifugal forcereplaces gravity, down appears to be up and upappears to be down!

Disorientation, in the pilot’s sense, (sometimesdescribed as “vertigo”) is to be unable to locateoneself in space and can be one of the most terrifyingand lethal of experiences. It has been invoked as acontributory cause in 12% of general aviationaccidents and in 15–20% of military accidents. Weorient ourselves by vision, the vestibular system andby proprioceptive nerve data. The mental images oforientation that we derive from these impulses arelearned from birth and relate to our terrestrial habitat.So strong are these sensations that it is possible toproduce nausea by placing us in an environmentwhere what we see is different to what we feel. Thisis the theoretical basis of motion sickness and will bedescribed later.

Vision

Vision is the strongest orienting sense, and the one towhich we turn when other senses fail. It isfunctionally divided into two parts. One, employingcentral foveal vision and sharp focus, is concernedwith object recognition and is used together withlearned conditioned reflexes in instrument flight. Theother, ambient orientation, is peripheral, less acuteand is directly connected to vestibular function. Thatthe two parts of vision are independent can beobserved in a driver who reads a map and follows theroad at the same time. Although we can orientourselves and function normally when the vestibularapparatus is absent or ablated, without visionorientation is much more difficult. However visioncan also give rise to illusions both of location and ofmovement. How strong an impression it can give isamply demonstrated by experiencing an IMAX©

movie where the camera appears to plummet theviewer through a ride on a roller coaster!

The Vestibular System

The vestibular system has three functions. It acts tostabilize vision via the oculo-vestibular reflexes, toorient the body in relation to movement in the

environment and to give a perception of motion.These functions are performed by two 1.5 cm.structures imbedded in the petrous bones of the skull.Each vestibule (see Fig. 10) consists of three bony,semi-circular canals lined by tubules containingendolymph. Each canal lies in a separate plane ofspace: one is horizontal, one vertical and one lateral.The canals sense angular accelerations in the planesof yaw, pitch and roll respectively. They areconnected at each end to the utricle, a dilated centralarea in which are the ampullae. In the ampullaedelicate hair cells topped by a gelatinous cupolaproject into the endolymph and move with it likeriver bottom plants in a current.

The utricle is connected to the saccule and in thefloor of these chambers are the macula (sacculi). Themacula in the utricle lies in the horizontal plane andthat in the saccule lies in the vertical plane. Themaculae consist of hair cells projecting into theendolymph and covered by a gelatinous membranecontaining tiny calcium carbonate crystals. They arereferred to as otoliths and act as linearaccelerometers.

Figure 10

VIEW OF THE RIGHT LABYRINTH

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The vestibular apparatus has connections to thevisual cortex, to the innervation of the extra-ocularmuscles and to the vestibular nuclei in the cerebrum.Try holding your hand up in front of your face andthen moving it from side to side. The movement doesnot have to be fast before focused vision of thefingers is lost. Holding the hand still however andmoving the head from side to side allows sharp focusto be maintained at much greater rates. Occulo-vestibular reflexes make this possible.

Proprioception

Proprioception is of only secondary importance tovision on the ground, but is much less reliable in theair. While flying, centripetal and centrifugal forcescompete with gravity and proprioception may beconfused. Although proprioception enables the pilotto stabilize his body in the cockpit and gives valuableclues to changing directions and attitudes in visualflying conditions, in instrument conditions “flying bythe seat of the pants” can rapidly become lethal. Inone experiment private pilots untrained in isntrumentflying were placed in a simulator and taken fromvisual flying conditions into dense cloud where theywere required to make a 180° turn. All crashed within178 seconds!

Visual Illusions

These may be foveal or vectional, that is concernedwith central vision or orientation vision. The formertype is often associated with landing approaches andis most common where visual clues are reduced orunfamiliar. A pilot approaching an unfamiliar runwaywith a minor uphill slope, for example, may feel thathe is too high and may fall below the normal glideslope. If the fields runs down hill, he may land long.Pilots inexperienced in the Arctic may miscalculatetheir height on final approach because the trees theyuse for unconscious reference are shorter than trees inthe South. Landing in “whiteout” conditions, wherethe ground and horizon are obscured, or landing on asmooth, reflective lake makes judgement of heightextremely difficult. Particular problems may occur atnight when approaching a lighted runway in anotherwise featureless area if in the distance there is awell lit town at a higher elevation. The eye, in theabsence of other clues, tends to place the two lightedareas on the same elevation which may lead topremature ground contact.

Autokinesis

There is a special problem at night with small lightsources, such as stars or distant ground lights. Whenwatched intently they will appear to move and maybe mistaken for other aircraft. This movement ofstationary objects is known as autokinesis and hasbeen responsible for accidents. Where the lightsource is bright or large this illusion is uncommon.

Vectional Illusions

The commonest type of vectional (movement)illusion is that experienced sitting in a car at a trafficlight when the adjoining car creeps forward. Thiscauses a sensation of backward movement and oftenreflex braking. In the rotational plane similarillusions occur. In a darknened chamber where lightfrom a rotating source is reflected on the walls, themovement of the light on the walls is soon replacedby a sensation of body rotation, the walls appearingfixed. Other problems are confusion between groundlights and the stars when flying over prairie areas orpilots orienting the aircraft to sloping cloud decks orto the Northern Lights rather than to the true horizon.

Vestibular Illusions

These may arise from the otoliths, the semicircularcanals or from a combination of the two. They areamong the most serious of the illusions and the mostlikely to cause lethal accidents.

At rest or in constant motion gravity is the only forceacting on the otolithic membrane. We are used tointerpreting gravity as a force pointing to the centreof the earth and, when our plane of movement ischanged, falsely interpret sensations according to thisprecept. A pilot accelerating down the runway androtating to lift-off is exposed to an acceleration whichpushes him back in the seat, together with the forceof gravity acting downwards. (Fig. 11).

The resultant is interpreted as a single force actingupwards and backwards. Because the brain interpretsthe force of gravity as being vertical, the sensation isof pitch-up and the pilot may instinctively make aforward stick movement for control. This cancomplicate the situation because causing negative Gstimulates an oculo-vestibular reflex movement ofthe eyes which gives rise to the sensation that theinstrument panel is moving upwards, heightening theillusion. This is the known as the o c u l o g r a v i c

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illusion. With deceleration, such as that experiencedon descent when the flaps are deployed, a pitch downsensation may be felt. These sensations are normaland of no great importance if the pilot is experiencedor visual flight is maintained. At night however,particularly taking off from a lighted runway into adark featureless area, and accident can occur due toinappropriate control movements performed in thetransition from visual to instrument flight. Even anexperienced pilot can take as long as 7 seconds toadjust.

The Leans

A common form of disorientation is a sensation ofincorrect rotation (or absence of rotation) caused bythe semicircular canals. The cupola in its neutralposition is upright. When the head rotates, the bonycanals move but there is inertia in the endolymph.

The cupola is therefore deflected leading to asensation of rotation. Our sensitivity to rotationhowever is not perfect and can be diminished by anyform of distraction. Rotation in the vertical axis of

1-3 per second may not be perceived. If a pilot, flyingstraight and level, gradually drops the left wing by15 degrees whilst otherwise occupied and suddenlybecomes aware from the instruments of this attitudeand corrects it at a much faster rate, only thecorrection will be sensed. The pilot then feels asthough the aircraft has rolled 15 degrees towards theright and will lean towards the left to maintainbalance. This is called “the leans” and is extremelycommon.

Figure 11

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Prolonged Turns

A different problem arises with prolonged turns at aconstant rate, such as those encountered in a holdingpattern at a busy airport. On entering a turn thecupola is deflected by the inertia of the endolymph(see Fig. 12). As the turn continues the endolymphwill begin to move until it is in equilibrium with thebony canal and at this point the cupola will return toits central position. (Depending on the steepness ofthe turn this may occur in 10-30 seconds). When theturn is terminated the bony canal will cease to rotateimmediately but the endolymph, due to inertia, willcontinue to swirl thus moving the cupola in theopposite direction. This gives rise to the impressionthat a turn in the opposite direction has been enteredand the tendency will be to correct this and so to re-enter the original turn.

The Graveyard Spiral

Although this is a minor distraction under mostcircumstances, in instrument meterologicalconditions it can be extremely serious and lead to a“graveyard spiral”. Here the inexperienced pilot,having inadvertently entered a steep descending turnunder instrument conditions, makes the correct stickmovements to control the aircraft but experiencingthe sensation of entering a turn in the other directionmay re-enter the spiral. As the aircraft is alsodescending, pulling back on the stick to stop the lossof altitude, although giving rise to a comfortingfeeling of gravitational pull in the seat, actuallysteepens the spiral, ultimately driving the aircraft intothe ground.

Figure 12

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SECTION 2

The Coreolis Phenomenon

The most extreme form of vestibular disorientation isdue to the Coreolis phenomenon. This is thought tobe caused when two different semi-circular canals arestimulated at the same time. As an example, a pilottaking off from an airport in instrument conditions,banks towards the left while climbing. So far there isstimulation of the otolith and of one canal. In order toreach a switch or see a gauge however the pilot turnsthe head quickly downwards and towards the right.Two different canals have now been stimulated and,as all are connected, a movement of endolymph takesplace in the third canal. The result is a sensation oftumbling which may be extreme and worsened byvisual problems due to oculo-vestibular reflexes.Even if control of the aircraft can be maintainedunder these very trying circumstances, the pilot maystill be subject to the leans or other abnormalsensations until able to obtain a visual reference.

Types of Illusions

Distinction is sometimes made between two differenttype of disorientation. Type I is unrecognized andType II recognized. Obviously a Type I illusion ismore likely to lead to an accident or incident.Illusions are also divided into oculo-gyral (somato-gyral) or oculogravic (somato-gravic). An oculo-gyral illusion is defined as the apparent movement ofan object in the visual field resulting from stimulationof the semi-circular canals by angular acceleration.An oculo-gravic illusion is the false perception of tiltinduced by stimulation of the otolith by linearaccelerations. The terms somato-gyral and somato-gravic refer to the resulting body sensations.

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MOTION SICKNESS

The relationship between this condition andorientation is striking. The causes of motion sicknessare both visual and mechanical, the latter arisingfrom stimulation of the vestibular system. Animals inwhom the vestibular system has been ablated orpeople born with non-functioning labryinths cannotbe made motion sick. The cause of motion sicknesshas never been completely clarified but it is felt thatit results from sensory conflicts, the diff e r e n c ebetween what is seen or felt and previousorientational experience. Motion sickness, forexample, can occur in aircraft simulators and is morecommon amongst pilots experienced on the type ofaircraft being simulated than it is in an inexperiencedcrew. It seems that the experienced pilot misses thecues of mechanical motion to which he/she isaccustomed when the sensation of motion is onlyvisually induced.

Frequency

Motion sickness increases in frequency up to pubertyand then decreases. Women are more subject thanmen and it is more common in passengers than ina i r c r e w. Motion sickness may be provoked bya n x i e t y, fear or orientational insecurity.Unfortunately it can become a conditioned reflex. Atrainee pilot, having been motion sick during flight,may become ill on the ground approaching anaircraft. It can be overcome by repeated exposure oradaptation and is rarely experienced by the person incharge of the aircraft (or automobile) who is aware,and braced for, changes in attitude or direction. Up toone third of military flight trainees become air sick atsome point in their training and about 1 in 5 suffersevere air sickness. Despite this less than 1% of thetrainees are failed because of this problem.Adaptation depends upon gradually increasingstimulation. In trainee pilots who develop severeproblems, desensitization programs have beensuccessfully employed.

Treatment

Motion sickness can be much reduced by the use ofScopolamine and nowadays transcutaneousadministration of this medication is used in seasickness. The drug however creates drowsiness andcholinergic effects and is not suitable for pilots.Small doses of the drug may be used in the initialphases of training when an instructor is in the aircraftbut this must be discontinued before solo flight isundertaken. There is no place for prolonged drugtherapy in aircrew.

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NEUROLOGY

04_Neurology 2004-02-26 2:40 PM Page i

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NEUROLOGY

CANADIAN GUIDELINES FOR THE ASSESSMENTOF NEUROLOGICAL FITNESS IN PILOTS,

FLIGHT ENGINEERS AND AIR TRAFFIC CONTROLLERS

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HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS N–1

NEUROLOGY

A continuing challenge for those involved in theaeromedical certification process is in makingdecisions which take into consideration both therights of the individual and the safety of the public.This is not always an easy task.

One of the areas that has been most challenging isneurology and neurosurg e r y. Making predictionsabout the likelihood of subtle or suddenincapacitation is at best an imprecise science.However, modern neurological diagnostic imagingtechniques and prospective studies are makingoutcome predictions more reliable.

These guidelines have been prepared to assistpracticing physicians determine whether or not theirpilot patients may meet the neurologicalrequirements for the aviation environment. T h eguidelines are the result of an analysis of theproceedings of a 2 day workshop on neurologicaldisorders and aeromedical certification held inOttawa, June 3rd and 4th 1992.

Physicians are reminded that this document should beused as a guide only and should not be confused withthe medical standards for aviation personnelpublished by Transport Canada, Aviation (TP 195).Specific questions should be directed to the nearestregional aviation medical office, Civil Av i a t i o nMedicine Division, Health Canada. (appendix)

To all the panel members who participated in theworkshop with such enthusiasm, and who gave sogenerously their expertise and precious time in thedevelopment of these guidelines I extend to each ofyou my sincere and respectful gratitude.

To Dr. Hyman Rabinovitch, neurology consultant tothe Civil Aviation Medicine Review Board, and Dr.James M. Wallace, Senior Consultant, OperationsPolicy and Standards who shouldered theresponsibility of writing and editing this document, Ithank you for your dedication.

FOREWORD

G.Y. Takahashi, M.D., D.Av.Med.

Director, Civil Aviation Medicine Division (CAM)

Health Canada

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N–2 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

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List of ParticipantsDR. GEORGE Y. TAKAHASHI

Director, Civil Aviation Medicine DivisionCAM, Ottawa

DR. JAMES M. WALLACE

Sr. Consultant, Operations, Policy and Standards,CAM, Ottawa,Co-Chairman

DR. HYMAN RABINOVITCH

Consultant in Neurology,Aviation Medical Review Board (AMRB), Asst. Clinical Prof. University of Ottawa Co-Chairman

DR. HENRY J. BARNETT

Professor of Neurology,University of Western Ontario, London, Ontario

DR. FREDERICK ANDERMANN

Professor of Neurology, McGill University,Montreal, Quebec

DR. ROBERT NELSON

Chairman, Division of Neurology,University of Ottawa, Ottawa, Ontario

DR. DONALD PATY

Professor of Neurology,University of British Columbia, Vancouver, B.C.

DR. DONALD STUSS

Director, Rotman Research Institute,North York, Ontario

DR. ROBERT DUPUIS

Consultant in Internal Medicine, AMRB, Ottawa,Assoc. Professor, University of Ottawa

DR. BRIAN ST. L. LIDDY

Consultant in Ophthalmology, AMRB, Ottawa

DR. DAVID SCHRAMM

Consultant in Otolaryngology, AMRB, Ottawa

DR. MARVIN LANGE

Consultant in Psychiatry, AMRB, Ottawa

DR. PAUL KING

Sr. Consultant Education & Training,CAM, Ottawa

DR. GUY SAVOIE

Chief Clinical Assessment,CAM, Ottawa

DR. STEPHEN V. BLIZZARD

Sr. Consultant, Safety and Human Factors,CAM, Ottawa

DR. BRENT HASKELL

Regional Aviation Medical Officer,CAM, Ontario Region

DR. JAMES NOLAN

Regional Aviation Medical Officer,CAM, Central Region

DR. JENNIFER GEGG

Regional Aviation Medical Officer,CAM, Western Region

DR. KENNETH BOYD

Regional Aviation Medical Officer,CAM, Pacific Region

DR. FRANÇOIS DUBÉ

Regional Aviation Medical Officer,CAM, Quebec Region

DR. HART CORNE

Acting Regional Aviation Medical Officer,CAM, Atlantic Region

MR. LARRY CUNDY

Superintendant, Personnel Licensing StandardsTransport Canada Aviation

DR. SILVIO FINKELSTEIN

Chief, Aviation Medicine Section, InternationalCivil Aviation Organization, Montreal

DR. WILLIAM HARK

Office of Aviation Medicine, Federal AviationAdministration, Washington, D.C., U.S.A.

DR. WILLIAM DOUGHTY

Director, Medical Services,Canadian Airlines International, Vancouver

DR. CLAUDE THIBEAULT

Director, Medical Services, Air Canada,Montreal

DR. GARY GRAY

Defence and Civil Institute of EnvironmentalMedicine, Downsview, Ont.Medical Advisor to Canadian Airline Pilots A s s o c .

CAPTAIN DAVID NOBLE

Canadian Airline Pilot’s Association


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NEUROLOGY

IntroductionThe Canadian Charter of Rights and Freedoms whichwas enacted in 1982 has a number of human rightsprovisions, one of which states that “no person shallbe discriminated against on the basis of disability”.Given this constitutional background there have beenan increasing number of challenges in the Courts andHuman Rights Tribunals on refusals to medicallycertify applicants with neurological disorders.Aeromedical “unfit” assessments must therefore bebased on current scientific “state of the art”knowledge.

In the aviation environment neurological disease is arecurring concern for those involved in aeromedicalcertification. The mode of presentation may varyfrom full-blown grand mal seizures or massive stroketo the insidious onset of cognitive impairment inconditions such as multiple sclerosis and Alzheimer’sdisease. The prevalence and marked variability inseverity of migraine has caused difficulty inobjectively deciding where the line should be drawnbetween “fit” and “unfit” assessments. The personwho has sustained a significant head injury is subjectto the dual dilemma of risk of posttraumatic seizuresand also of cognitive impairment.

In 1977 in the United States, the Federal AviationAdministration solicited a proposal from theAmerican Medical Association (AMA) to produce an

authoritative report on neurological disorders andaviation safety. The AMA in conjunction with theAmerican Academy of Neurology and the AmericanAssociation of Neurological Surgeons convened aseries of meetings with experts in the field whichresulted in the publication in 1979 of a special issueof the Archives of Neurology, entitled “Neurologicaland Neurosurgical Conditions Associated withAviation Safety”. This document served as one of theprimary resources for Canadian aeromedicalcertification decisions on neurological disordersthroughout the 1980’s.

Advances in diagnostic imaging and the managementof neurological and neurosurgical disorders over theintervening years indicated that more currentreferences were required. In order to address theseissues, Health & Welfare Canada’s Civil AviationMedicine Division held a conference in June 1992 inOttawa, inviting experts in the field of neurology todiscuss the more common neurological disorders andtheir relationship to aviation safety.

The conference served as a basis for the series ofguidelines published below.

It should be pointed out that this document is onlyguidance material and that each decision will bebased on the individual circumstances of the case.




Head Injury

General

There are two major concerns following head traumaresulting in loss of consciousness. One is theneuropsychological consequences of the trauma inpatients who have not had any focal deficits. Theother is the possibility of seizure secondary to thetrauma.

The neuropsychological consequences are secondaryto the effects of acceleration/deceleration forces onthe skull and brain. Because of the anatomy involved,these forces cause their greatest focal damage to theorbital, frontal and anterior temporal areas of thebrain. Associated with the cortical damage there isdiffuse white matter damage.

The result of this is dysfunction in a number offunctional executive activities of the brain. Thesefrequently are, 1) slowing of reaction time, impairedmemory and deficient ability to perform constantly ata high level over time, particularly in settings ofcomplex activities and choices. 2) A high propensityfor further mental decline with fatigue. Otherproblems include attention, initiation and propersequencing of tasks, difficulty in planning andanticipating the future, and difficulty establishingautomatic responses to a trigger. The aff e c t e dindividual may not notice or care that the task isbeing poorly performed. Problems are exacerbatedby stress, fatigue and pain and the handling ofsimultaneous emergency tasks is particularlyaffected. Although the problems may be severe,routine IQ and mental status testing may be withinnormal limits. Fortunately there is a natural tendencyfor deficits to improve.

Prediction of Neuropsychological Outcome

Sufficient data to accurately predict the outcome ofmost types of head injury is unfortunatelyunavailable. There are a number of ways to predictthe outcome of head injury and the most commonlyused to date has been the duration of post-traumaticamnesia (PTA). Most individuals who have had aPTA of less than 30 minutes are likely to be fit withinthree months. Older individuals and/or those whohave a history of previous concussion are of greaterconcern. A person with PTA lasting more than 30minutes but less than 24 hours will likely be fit froma neuropsychological point of view after a longertime, probably one year.

Those with focal neurological deficits, those whohave focal abnormalities on CT scanning or a moreprolonged PTA require neuropsychologicalassessment with particular attention to frontal lobefunctioning before medical certification. Flightsimulator testing may be useful. Magnetic resonanceimaging (MRI) is more sensitive than CT scanning indefining areas of frontal lobe and white matterabnormality and is therefore an important diagnosticadjunct in those who have had brain injuries. Thesepeople clearly require a more prolonged period offwork than those with simple concussion.

Prediction of Posttraumatic Epilepsy

The probability of epilepsy is greater in those withpenetrating skull injuries. Even with full physical andneuropsychological recovery there is an increasedprobability of seizures for over ten years. In general,of those who develop post traumatic seizures, 50%will occur within one year and 70 - 80% within twoyears. Thereafter the incidence is 3 - 5% per year upto ten years. The probability of seizures has beencorrelated with CT scan findings as illustrated inTable 1.

Aeromedical Status

1. Those with PTA lasting 30 minutes or less, whoafter the event, have a normal neurologicalexamination without sequlae, may be medicallycertified in three to four months if the CT scan isnormal.

2. Those with PTA lasting from 30 minutes to 24hours but with a normal MRI and EEG, may bemedically certified by one year. If a seizureoccurred in the first week after trauma in anadult, a longer interval before medicalcertification is indicated.

3. Those with PTA greater than 24 hours but whohave normal neuroimaging andneuropsychological testing, may be medicallycertified by two years. Flight simulator testingmay provide additional valuable information inthese cases.

4. Those with closed head injury with extracerebralhaemorrhage, but without dural tear orintracerebral involvement may return to fullduties by five years. An EEG and neuroimagingshould be undertaken at that time.


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NEUROLOGY

5. Those with closed head injuries with associatedintracerebral haemorrhage or focal deficit, butwhose neuropsychological testing does not showsignificant residua 7 years post trauma, may beconsidered at that time. Those who demonstrateabnormal neuropsychological residua have beenmore seriously injured and should be consideredindividually.

6. Those with penetrating skull injuries from amissile are unfit for 15 years even ifneuropsychologically normal because of thecontinuing excess risk of posttraumatic epilepsy.

Chronic Subdural Hematoma

These can occur at any age, though they are morecommon in the older age group. Individualsfrequently are unaware of significant head trauma.

Postevacuation if the applicant has;

1. no sequelae and

2. no seizures in the year following surgery and

3. no significant abnormality on CT scanning andsleep deprived EEG, they may be considered formedical certification.

Table 1

RISK FACTORS FORLATE POSTTRAUMATIC EPILEPSY

INCIDENCE OFLATE SEIZURES

(%)

Penetrating injury caused bymissile

Intracerebral haematoma –laceration

Focal brain damage on earlyCT scan

Early seizures

Depressed fracture – torn dura

Extradural or subduralhaemorrhage

Focal signs (hemiplegia,aphasia, ..)

Depressed skull fracture

Loss of consciousness> 24 hours

Linear fracture

Mild concussion

53

39

32

25

25

20

20

15

5

5

1

Pagni C.A. (1990)Post-traumatic Epilepsy and Prophylaxis:

Acta Neurochirurgica, Suppl. 50, 38-47 (1990)


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Stroke and Transient Ischemic Attack (TIA)

GENERALStroke is the third most common cause of death anda leading cause of disability in Canada. The risk of arecurrent stroke following an initial TIA or stroke hasbeen looked at in a number of trials of various anti-platelet medications. These studies show about an 8%per annum risk of recurrence and about 2-3% risk ofa myocardial infarction. The probability ofrecurrence does depend on the number of risk factorspresent and the degree of carotid artery stenosis.Blood pressure control, cholesterol control, anti-platelet medications and cessation of smoking havemade significance inroads into reducing the risk ofstroke. Surgery has been particularly successful inpatients who have significant carotid stenosis.Nevertheless, despite these management techniques,the risk of recurrent stroke remains high. Therefore,the vast majority of applicants who have had a stroke,will remain permanently unfit. All applicants withstroke secondary to an intracerebal hemorrhage arepermanently unfit.

MODIFYING CONSIDERATIONS

Transient Ischaemic Attacks

The applicant who has a TIA must be evaluatedcarefully as some will in reality be migraine withoutheadache, seizures, vestibular dysfunction, failure ofocular fusion, multiple sclerosis, brain tumors,subdural hematoma, hypoglycemia or syncope. Riskfactors have to be carefully evaluated includingpossible cardiac sources of embolus. Applicants withnegative imaging of brain, neck and heart and withminimal other risk factors can be considered formedical certification at three years after the event.

Lacunes

These are a specific symptom complex with anappropriate abnormality on neuroimaging ascribed toa lacune. The majority are secondary to small vesselocclusion, others may be secondary to an embolus ofvarious possible origins. They pose two problems oneis the risk of recurrent infarct which is significant andthe second is the accumulation of lacunes withoutobvious symptomatology but leading to the insidiousonset of dementia The majority of applicants withlacunar infarcts are therefore unfit. Occasionalindividuals who never had significant deficits andwho fully recovered may be considered on anindividual basis. These individuals require extensive

work-up, including carotid Doppler studies andechocardiography. They need an MRI to show ifthere is evidence of significant lacunar disease. If theabove investigations do not show significantpathology, the risk factors are controlled and if afterfour years, the MRI does not show any increase oflacunar disease, the applicant could be considered onan individual basis for medical certification.Applicants with multiple lacunes are a concern, asthey may be developing dementia and are unfit.

A patent foramen ovale should not be considered arisk factor for stroke according to recent trials, unlessassociated with an atrial septal aneurysm.

Cerebral Venous Thrombosis

Approximately 70% of people who have venousthrombosis, have a clear predisposing factor, such asfactor 5 Leiden deficiency, Protein C or S deficiency,anti-thrombin 3 deficiency, or, PGM deficiency,trauma, infection or dehydration, anovulents,pregnancy and Methylenedioxymetamphetamine(Ecstasy). If there is no evidence of an ongoing orrecurrent risk, if there has been no evidence ofepilepsy and if the person has no significant sequelaefrom the thrombosis, they can be consideredmedically fit two years after the event.

Pregnancy in Stroke

During pregnancy and puerperium the risk of strokeis 44 per 100,000. The cause for this type of strokemust to be sought as often multiple factors predisposetowards such strokes. One has to look particularly forthrombophilia, anti-phospholipid antibodies,dehydration, cardiac disease and dissection. In thoseindividuals where there has been no significantsequelae, particularly no cognitive difficulties orhistory of epilepsy and if the etiology of their strokeis not going to be a recurrent or ongoing problem,then they could be considered fit two years afterthe event.

Asymptomatic Stenosis

Applicants who are found to have an 80% or greaterstenosis of the carotid artery are at increased risk ofstroke , TIA or myocardial infarct. They are unfit. Anendarterectomy will not resolve this problem, as theyprobably have other arteries significantly involved.



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Arterial Dissections

Arterial dissections are one of the most commoncauses of stroke in the young. Applicants who havehad a good recovery, in which imaging does not showany evidence of cerebral infarction, who have had noevidence of epileptic seizures, can be considered formedical certification after two years. They needimaging to show good restitution of flow, with noevidence of aneurysm. There should be no evidenceof having had a subarachnoid hemorrhage. Thereshould be no predisposition to further dissections.

Ruptured Aneurysms

The majority of applicants who have had asubarachnoid hemorrhage are permanently unfit.There are occasional people who have beensuccessfully treated, who had excellent recovery, andwho have never had seizures. Those individuals inwhich repeated angiography shows that the treatmenthas been successful can be considered for medicalcertification at two years. If they had an endovascularapproach, an angiogram should be repeated yearly

for two further years, to show that successful repairhas been maintained. An EEG at two years should notshow significant abnormalities and particularly nopotentially epileptiform discharges. Those who haveperimesencephalic bleeds with normal angiography,could be considered fit at one year if they have had anexcellent recovery, as is usually the case. Those withasymptomatic intracranial aneurysms less than1 0 mm can be considered as continuing to bemedically fit.

Arterio Venous Malformations

Those who are asymptomatic usually have a risk of2-4 % per year of hemorrhage. Those who have beenpreviously symptomatic have a risk as high as 33% inthe first year. Therefore those with arteriovenousmalformations are permanently unfit.

Cavernomas

Applicants with cavernomas that are deep, with noevidence of previous hemorrhage may be consideredfit, all others should be considered unfit.


Seizure Disorders

GENERALThe tendency towards epileptic seizures is not an allor nothing phenomenon. Most people, under certainconditions, may have a seizure if sleep deprived orwithdrawing from alcohol or benzodiazapines,especially if in addition they are taking medicationswhich decrease the seizure threshold (eg. Tricyclicanti-depressants). Approximately 2% of thepopulation will have a seizure during their lifetime.

An adult with a single seizure has a 30 - 40% chanceof recurrence. Those with a distinct epileptiformabnormality on the EEG as opposed to non specificabnormalities, have an increased probability ofhaving further seizures after a single seizure. It istherefore imperative that the diagnosis of a seizure becorrect, and the importance of a description of theevent cannot be overemphasized. Although theelectroencephalogram (EEG) is particularly useful itmust be reviewed by an experienced reader to beconsidered supportive of an epileptiform tendency.Individuals with epilepsy are unfit.

Persons who have had the following types of seizuresmay be acceptable. Childhood febrile seizures whichare brief, not associated with neurological deficits,and have ceased before the age of five may beconsidered for medical certification. The individualmust have been off all anti-epileptic medications forat least five years and the EEG (off medication) mustbe normal. The seizures of Benign Rolandic Epilepsyof Childhood usually involve the face, tongue orhand and are often precipitated by drowsiness orsleep. The EEG shows significant abnormalities fromthe Rolandic area of the brain. Individuals with thiscondition may be considered for medical certificationif they have been seizure free and off medication forten years. They must have a normal neurologicalexamination and EEG. A sleep deprived EEG shouldalso be normal.

THE SINGLE EPILEPTIC SEIZUREAn individual with a single epileptic seizure isinitially unfit. The case can be reconsidered after fiveyears if the neurological examination is normal andrepeated EEGs, including sleep deprivation andadditional nasopharyngeal or minisphenoidalelectrodes, do not reveal any significantabnormalities. Neuroimaging, preferably MRI, mustfirst have revealed a normal brain structure. Arestricted (as or with co-pilot) medical certificate can

then be granted. Such a restriction may be removedafter an additional two years. Those individuals whohave a second seizure should be considered to haveepilepsy.

Five years after the event, all of the aboveinvestigations must be repeated and found to benormal. Applicants for Category 1 medicalcertification should be restricted to: “as or withcopilot” for an additional two years. T h o s eindividuals who have a second seizure should beconsidered to have epilepsy.

When a single seizure was related to alcoholwithdrawal, individuals may be considered earlier ifthey have a normal EEG and neuroimaging andpsychosocial and biochemical evidence is presentedthat their alcohol abuse/dependence is in a continuing“recovery” phase.

Those who have had a seizure while on tricyclic anti-depressant drugs or other seizure enhancingmedications must be considered more prone toseizures than the average population. They must beconsidered unfit for five years.

TRANSIENT GLOBAL AMNESIA (TGA)This condition is characterized by a transient loss ofmemory for remote events associated with aninability to form new memories. It is an unusualcondition that usually lasts for hours. TGA is not aseizure disorder and may be due to transient ischemiain the inferomedial parts of the temporal lobes. It iscommoner in middle aged or older people, and manyindividuals are hypertensive: frequently they havebeen undertaking physically demanding tasks (eg.shoveling snow) or under significant mental stress atthe time of the attack.

Throughout the episode, the sufferer is sociallyappropriate, oriented to person but tends to repeat thesame question over and over again, this questionusually reflecting their disorientation. (eg. “What amI doing here?”) A number of series have shown a 10- 20% recurrence, most of which occur within thefirst five years.

If there is a normal neurological examination andEEG at the time of the event and again one year afterthe event, medical certification may be considered.




NARCOLEPSYNarcolepsy presents with periods of excessivedaytime sleepiness not prevented by adequate night-time sleep and often enhanced by boredom.Excessive sleepiness may be associated with sleeprelated hallucinations or paralysis and, mostimportantly, it may be associated with cataplexywhich is an abrupt paralysis of variable degreeprecipitated by surprise or by laughter. Prophylacticmedications are imperfect and may alterperformance. They include dextroamphetamine andmethylphenidate.

Narcolepsy is a lifetime illness and the sufferer ispermanently unfit.

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Headaches

TENSION AND MIGRAINE HEADACHES

General

Fifty-nine percent of the adult population in Canadareport some form of headache. Thirty percent sufferfrom tension-type headaches, and 17% suffer fromsome form of migraine. Tension type headaches arenot usually disabling but up to three quarters ofmigraine headaches are sufficiently severe to limitregular activities. Most migraineurs have attacks thatlast 12 to 24 hours.

Migraine can be divided into two categories,migraine with aura (classical migraine) and migrainewithout aura (common migraine). The aura may bepreceded by a prodrome of mood changes which mayinterfere with routine activities. The aura itselfusually lasts about 20 minutes and immediatelyprecedes the onset of the headache. The cause of theaura has been debated but may be secondary tometabolic and/or electrical changes which maypossibly be accompanied by ischemic change in thecerebral cortex. The head pain itself is thought to berelated to a sterile inflammatory response aroundblood vessels in the face and scalp and the intra-cranial vessels of the coverings of the brain. Thisinflammatory response is mediated throughvasoactive peptides which cause dilatation, edemaand inflammation around the vessels which areinnervated by a branch of the trigeminal nerve(trigeminal-vascular complex).

Migraine tends to occur at times of let-down fromstress, after fasting, and after missing sleep. Flashinglights and bright reflected light may also trigger acuteattacks.

Aeromedical Status

Migraine without aura – Most applicants will beconsidered fit.

Migraine with Aura

Group 1.

Applicants with auras which:

a) would not interfere with flight safety and,

b) have been consistently the same aura overseveral years, can generally be consideredfor medical certification.

Group 2.

Applicants with auras that:

a) are of slow onset; and

b) occur infrequently ie. once every severalmonths; and,

c) are not associated with cognitiveimpairment, but may cause minor sensorydifficulty that does not impair performance;and

d) have been consistently the same over severalyears.

Group 3.

Migraineurs who have significant auras whichcan interfere with flight safety and who do not fitinto the group 2, (ie, too fast onset, too frequent,cognitive impairment, unclear history,) shouldgenerally be considered unfit for all categories.They may be considered for restricted medicalcertification if after 3 years they fit in group 2.

Cluster Headaches

Cluster headaches occur only in 0.1% of thepopulation and are generally episodic and 80% of thecases occur in men. The headaches usually last aboutone hour and 50% of the cases begin during sleep.They recur in bouts lasting six weeks or more, duringwhich time acute attacks occur one to four times per24 hours. Once the bout is ended, however, thes u fferers are usually entirely headache free formonths or years. The individual attacks are extremelyintense, localized around one eye and associated withnasal congestion and lacrimation which may impairvision. They are virtually always incapacitating. Theapplicants should be considered unfit during a bout ofcluster headache but during the interval bouts, theymay be considered fit. Between bouts, the applicantsdo not need to take any medication, but in chroniccluster headache where the bout extends beyond sixweeks, medication which might impair functioningmay be required.




Trigeminal Neuralgia

Trigeminal Neuralgia causes piercing, electric shock-like facial pains which have a high frequency ofrecurrence. Many episodes may occur in a single day.In older age groups these are often secondary to aloop of blood vessels pressing against the trigeminalnerve: in the young they may be secondary tomultiple sclerosis. Individuals suffering fromtrigeminal neuralgia are unfit but if they go intoremission may be considered for medicalcertification.

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Multiple Sclerosis

GENERALMultiple Sclerosis (MS) has a prevalence of aboutone in a thousand in Canada. The peak incidence is inthe early 30’s with more females than males beingaffected. It is the third most common cause of severeneurological impairment in the 15-60 year age range.The course is variable. Some will have a relapsing,remitting course and 20 - 30% will have a benigncourse. Fatigue is one of the most disabling problemsin patients with multiple sclerosis. In 60% of thepatients the symptoms are exacerbated by an elevatedambient temperature.

Flight Safety Concerns

1. Functional Disabilities

Though many of these will be readily apparentfrom a practical flight test, (eg. weakness, lack ofcoordination etc.) they also include problemswith excessive glare in bright light and increasedlevels of fatigue.

2. Neuropsychological Deficits

40% of the patients with MS have been found tohave neuropsychological problems. This issignificantly but weakly correlated with thedegree of functional disability.

3. Paroxysmal Events

Epilepsy occurs in 5% of patients with MS.Trigeminal Neuralgia is commonly a symptom ofMS when it occurs in the young. Paroxysmaldysfunction of motor or sensory systems mayoccur with this disease.

Recommendations

1. Functional Disabilities

Individuals with functional disabilities thatinterfere with the mechanics of flying or thosewho have a progressive course of MS will beconsidered unfit. This is also true of those whos u ffer significant fatigue or heat sensitivity.Individuals who have a remitting/relapsingcourse may be considered fit when they havebeen in remission for three months provided theremission is complete or with minimal residua(eg. Expanded Disability Score of less than 2 ona scale of 0 - 10). Such individuals will requireneurological follow-up every six months.

2. Neuropsychological Sequelae

Because of the concern for subtleneuropsychological deficits, applicants shouldprobably be followed by a neurologist withexpertise in M.S. Neuropsychological testingshould be considered periodically especially inthose who have significant fluctuation insymptoms. Flight simulator testing may be usefulin assessing cognitive function. The role of MRIto delineate those who may haveneuropsychological deficits has not been definedat this time. Those with marked involvement ofthe white matter with MS plaques, particularly ifthe involvement is bifrontal, should haveneuropsychological testing and, if indicated, apractical flight test.

3. Paroxysmal Events

A. Epileptic Seizures

These individuals are permanently unfit.

B. Trigeminal Neuralgia

Applicants are unfit during periods when they aresymptomatic. It is unusual for these to resolveand most continue to be unfit.

C. Other Paroxysms

Usually these are of limited duration. If theyresolve and are absent for four months offmedication the individual can be reconsidered formedical certification.




TumorsGENERALTumors arising from the brain parenchyma such asgliomas or ependymomas, even when removed andwhether or not they are treated with a radiotherapy,leave behind scarring. This increases the probabilityof seizures and applicants with such a history aretherefore permanently unfit.

Meningiomas

Applicants who have had meningiomas of thecerebral convexities may be considered fit two yearspost resection under certain specific circumstances.Current literature suggests that there is no limit as towhen a meningioma can recur. The tumor must havebeen fully removed as defined by repeatedneuroimaging. There should be no neurologicalsequelae and no history of seizures in associationwith the tumor. If a medical certification is granted arepeat EEG and CT scan must be done at yearlyintervals.

Infratentorial Meningiomas, Acoustic Neuromas,Pituitary Tumors and other Benign Extra-axialTumors

Applicants who have had complete resection of aninfratentorial meningioma, acoustic neuroma or otherbenign extra axial tumors, or applicants who havehad a transphenoidal complete resection of a pituitarytumor and have no neurological or endocrinologicalsequelae and no history of seizures may be relicencedafter 6 months to one year. They will require yearlyneurological and endocrinological follow-up.

Those who have had an elevation of the frontal lobesin order to approach the pituitary tumor are generallyunfit. This is because the tumor is probably larger andmore likely to disturb structures around it and thefrontal lobe has been disturbed by the tractioninvolved in the surgery. These factors increase thechance of the applicant developing seizures.

TRANSPORT CANADA


NEUROLOGY


Miscellaneous Illnesses

Hydrocephalus

Individuals who have required a shunt to controlhydrocephalus may have shunt failure and/or requirea new shunt. Those shunted for acquiredhydrocephalus are generally unfit because of thepossibility of unexpected shunt failure. Individualconsideration however may be given whereaccredited medical opinion is that the risk of shuntfailure or seizure is low.

Applicants shunted in infancy and seizure freethroughout adult life without neuropsychologicalsequelae may be considered for a Category 3 medicalcertificate.

Syringomyelia

This is a rare condition in which there is a cysticlesion of the spinal cord or brainstem. These lesionsusually develop because of congenital anomalies,less frequently secondary to trauma or tumor. Theytend to progress.

If the syrinx is below the cervical cord the applicantshould be judged as any other paraparetic accordingto functional abilities. A practical flight test will berequired and, after medical certification, neurologicalfollow-up is required every six months. A practicalflight test should be repeated annually.

In applicants where the syrinx involves the cervicalcord or brainstem, the neurological deficit may be orbecome too significant for medical certification.Such applicants are permanently unfit.

Myasthenia Gravis (MG)

Neuromuscular dysfunction in MG is related toantibodies generated against the acetylcholinereceptor at the neuromuscular junction. This resultsin progressive weakness and fatigability whichfluctuates with the degree of effort sustained. Someindividuals may achieve a remission by thymectomyor immunosuppression. Those who are in remissionand stable, with little or no medication two years afterthe thymectomy, may be recertified.




Infections1. Viral Meningitis

An applicant who is neurologically normal at twomonths after infection will be considered fit, allcategories.

2. Bacterial Meningitis

If the individual is found to be neurologicallynormal on examination, electroencephalographyand CT scanning and if they have had no focal orneurological deficits or seizures during thebacterial meningitis, they may be considered fitafter one year.

If there were complications such as focalneurological deficits, persistent cognitive deficitsor seizures, the applicant must be fullyneurologically intact for five years while off allmedications before being recertified. A repeat CTscan, EEG and a neurological assessment shouldbe performed at five years prior to recertification.If there were cognitive deficits post resolution,neuropsychological testing should be carried out.

3. Viral Encephalitis

The most common, sporadic, viral encephalitis in

North America is Herpes Simplex encephalitis.Neuropsychological sequelae are virtuallyalways present, even in those who have survivedseemingly neurologically intact.

Generally applicants who have suffered thisdisease will be permanently unfit. In caseshowever where there is complete neurologicalrecovery and neuropsychological testing showsno significant deficit, individuals who have nothad a seizure for five years off all medication canbe considered for medical certification. If thedisease manifested minimal or no cognitivedysfunction then a shorter unfit period prior tomedical certification may be considered.

4. Brain Abscesses

Applicants who have had a brain abscess are atan increased risk for epilepsy from the scarringthat forms around the abscess. They are thereforepermanently unfit.

5. Guillain-Barré Syndrome

Applicants who have made a satisfactoryneurological recovery may be certified followinga successful practical flight test.

TRANSPORT CANADA


NEUROLOGY


Degenerative Disease of the Brain

1. Parkinson’s Disease

Most applicants with Parkinsonism suff e rphysical and/or cognitive deficits which renderthem unfit. Individuals who have minimalParkinson’s disease, such that they do not requireL-dopa or an L-dopa agonist, may be certified.All patients licensed with Parkinson’s diseasemust have a satisfactory neurological assessmentat each renewal and more frequently if clinicallyindicated.

2. Dementia

Applicants with dementia are permanently unfit.In the small number of cases where the cause ofthe dementia is known and the condition has beenresolved, applicants may be considered forrecertification.




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CARDIOVASCULAR

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TRANSPORT CANADA


CARDIOVASCULAR

GUIDELINES FOR THE ASSESSMENT OFCARDIOVASCULAR FITNESS IN

LICENCED AVIATION PERSONNEL2003

http://www.tc.gc.ca/CivilAviation/Cam/TP13312-2/cardiovascular/menu.htm

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TRANSPORT CANADA


The presence or development of cardiovasculardisease in licenced aviation personnel, with the riskof potential clinical manifestations, continues to be amajor concern amongst aviation medicalpractitioners world-wide.

With improvements in modern methods of medicaland surgical treatment of cardiovascular disease,many pilots and air traffic controllers have been ableto return, after successful treatment, to licencedduties without jeopardizing aviation safety.

This third edition of the Canadian cardiovascularguidelines to assist in the medical assessment ofcardiovascular fitness of licenced aviation personnelreflects some changes as a result of discussions andrecommendations during the aviation cardiologyworkshop held in Ottawa, on December 3rd, 2001,arranged by Civil Aviation Medicine Branch,Transport Canada.

Physicians are reminded that these guidelines are tobe used as a guide only, and they should not beconfused with the medical regulations set out in theCanadian Aviation Regulations part 424 published byTransport Canada.

Civil Aviation Medicine Branch, Transport Canada,is again grateful for the enthusiastic support andparticipation of all the expert panel members, andother individuals who provided advice and criticism.Finally, a special word of thanks to Drs. James M.Wallace and Andreas T. Wielgosz for their efforts inplanning and co-chairing the workshop, and takingon the task of writing the text.

Comments are welcome, and any specific questionsshould be directed to Civil Aviation MedicineBranch, Transport Canada, Ottawa or to any RegionalAviation Medical Officer. Contact information isavailable from the Branch website atwww.tc.gc.ca/civilaviation/cam

FOREWORD

H.J. O’Neill, M.D.,D.Av. Med.

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List of Participants

CHAIRPERSONS:

DR. JAMES WALLACE

Civil Aviation Medicine, Transport Canada,Ottawa

and

DR. ANDREAS T. WIELGOSZ

Consultant Cardiologist,Aviation Medical Review Board,Head, Division of Cardiology,The Ottawa Hospital – General Campus andProfessor, Departments of Medicine and

` Epidemiology and Community Medicine,University of Ottawa.

PRINCIPAL AUTHOR:

DR. ANDREAS T. WIELGOSZ.

INVITED SUBJECT MATTER EXPERTS:

DR. MICHAEL FREEMAN

Director Nuclear Cardiology,St. Michael’s Hospital, Toronto, Ontario

DR. ERIC A. COHEN

Director, Cardiac Catheterization LaboratoryStaff Cardiologist, Sunnybrook & Women’sCollege Health Sciences Centre, Toronto, OntarioAssociate Professor of Medicine,University of Toronto

DR. L. BRENT MITCHELL

Cardiologist; (Electrophysiology)Foothills Medical Centre, Calgary, Alberta Professor, University of Calgary

DR. SIMON W. RABKIN

Cardiologist; Vancouver Hospital &Health Sciences Centre, Professor of Medicine,University of British Columbia

DR. IAN G. BURWASH

University of Ottawa Heart Institute,Associate Professor of MedicineUniversity of Ottawa

DR. STUART J. SMITH

Internal Medicine and CardiologySt. Mary’s General HospitalKitchener, Ontario

DR. GARY GRAY

Internal Medicine and Cardiology Defence Research and Development-CanadaToronto, Ontario

DR. HUGH J. O’NEILL

Director, Civil Aviation Medicine,Ottawa, Ontario

DR. GUY SAVOIE

Senior Consultant Clinical Assessment,Ottawa, Ontario

DR. FRANÇOIS DUBÉ

Marine Medical Consultant,Ottawa, Ontario

DR. ROBERT FLOOD

Aviation Medical Officer, Ontario Region,Toronto, Ontario

DR. JAMES PFAFF

Regional Aviation Medical Officer,Ontario Region, Toronto, Ontario

DR. EDWARD BROOK

Regional Aviation Medical Officer,Atlantic Region, Ottawa, Ontario

DR. JAY DANFORTH

Regional Aviation Medical Officer,Prairie & Northern RegionEdmonton, Alberta

DR. JOCELYN DENAULT

Internal Medicine Consultant,Aviation Medical Review Board

DR. ROBERT FASSOLD

Aviation Medicine Consultant,Aviation Medical Review Board

DR. GEORGE TAKAHASHI

Aviation Medicine Consultant,Aviation Medical Review Board

TRANSPORT CANADA


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TRANSPORT CANADA


Table of ContentsCARDIOVASCULAR

Page

INTRODUCTION

Chapter 1: Acute Ischemic Syndromes

Chest Pain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–4

Following an Acute Ischemic Syndrome Including Myocardial Infarction . . . . . . . . . . . . . . . . . . . . . . . . . . C–4

Following Revascularization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–5

Risk Factors for Ischemic Heart Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–5

Smoking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–5Increased Serum Cholesterol Llevels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–5High Blood Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–7Therapeutic Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–7Multiple Risk Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–8Comments on Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–8

Chapter 2: Non-Ischemic Heart Disease

Valvular Heart Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–10

Aortic Stenosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–10Aortic Regurgitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–10Follow-up Aortic Valve Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–10Mitral Stenosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–10Mitral Regurgitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–10Mitral Valve Prolapse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11Follow-up for Mitral Valve Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11Surgical Repair or Replacement of Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11

Congenital Heart Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11

Atrial Septal Defect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11Coarctation of the Aorta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11Pulmonary Stenosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11Ventricular Septal Defect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–11Tetralogy of Fallot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–12Transposition of Great Arteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–12

Inflammatory Heart Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–12

Cardiomyopathy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–12

Cardiac Transplantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–12

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Chapter 3: Dysrhythmias

Supraventricular Dysrhythmias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–14

Sinus Node Dysfunction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–14

Atrial Fibrillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–14

Pre-Excitation Syndromes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–14

Ventricular Dysrhythmias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–14

Conduction disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–15

Bundle Branch Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–15

Cardiac Pacemakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–15

Implanted Cardiac Defibrillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–15

Chapter 4: Vascular Disorders

Aneurysm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–18

Asymptomatic Carotid Bruit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–18

Arterial Thrombosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–18

Venous Thrombosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–18

Pulmonary Embolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–18

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–19

TRANSPORT CANADA


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TRANSPORT CANADA

HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS C–1

CARDIOVASCULAR

IntroductionIt is appropriate to have another update of theGuidelines for the Assessment of CardiovascularFitness in Canadian Licenced Aviation Personnel,although there have been few significantdevelopments in the field since the last one publishedin 1995. Most importantly perhaps, the overallpopulation of aviators in Canada is aging. Whereas in1986, half (49%) of all pilots were 40 or more yearsold, in 2001 that proportion was up to 63% andamong professional pilots the proportion rose from32% to 50%. Consequently the likelihood of acardiovascular event is increasing. While age alonecannot be used as a discriminating factor, it must betaken into consideration when assessing overall risk.A review of Canadian aviation medical guidelines in1996 determined that current criteria adequately takeinto consideration the impact of age on risk.Nevertheless examiners must be mindful of evennormal physiological changes associated with agingand their possible impact on flight safety.

Aviation Medical Standards as laid down in Annex 1to the Convention on International Civil Aviation bythe International Civil Aviation Organization (ICAO)to which Canada is a contracting state, identify broadmedical conditions that on the basis of expected riskof incapacitation disqualify a pilot from flying anaircraft. Such conditions, e.g., acute ischemicsyndromes are reportable to Transport Canada andresult in immediate revocation of medicalcertification. In countries where the standards areapplied strictly, affected pilots may never return toflying. Such a strict policy may be unfair to thoseaviation personnel in whom the risk of suddenincapacitation becomes acceptably low as a result ofrisk factor modification or rehabilitation includingsome therapeutic interventions. Our ability to predictrisk in an individual is improving as experience withgroups bearing similar risk profiles increases.Progress with the assurance of a safe flyingenvironment e.g. through widespread incapacitationtraining, has also allowed more tolerance of certainmedical conditions.

The risk of a fatal accident occurring as a result ofmedical incapacitation is dependent on a number offactors. These include the amount of time spentflying, the risk of an incapacitation occurring at acritical phase of flight and the risk that suchincapacitation will inevitably result in a catastrophicaccident. All of these factors must be taken intoconsideration in addition to the known medical riskof a given medical condition. Experience withcardiac disease in the general population along withexperience with simulators allow the estimation ofrisk in a fashion similar to that used by structuralengineers. It can be rationalized that an annual risk ofincapacitation up to 2%* due to a medical conditioncan be tolerated in an unrestricted flyingenvironment, as that would translate into anacceptably low risk of a resulting fatal accident.Where there is insufficient precision in estimatingrisk for the medical condition of a given applicant,then a determination of medical fitness should err onthe side of caution.

As with the previous guidelines, a one day workshopto review and update existing guidelines oncardiovascular fitness was organized in Ottawa onDecember 3rd, 2001 with the participation ofRegional Aviation Medical Officers, cardiovascularand aviation medicine consultants and staff from theCivil Aviation Medicine Branch, Transport Canada.In this edition we have also tried to clarify andambiguities or inconsistencies. We continue towelcome your suggestions to make the guidelines apractical document that is supported by the bestscientific evidence available.

Andreas T. Wielgosz

James M. Wallace

* A 2% risk of incapacitation includes a 1% risk due to a fatal occurrence as well as a 1% risk due to anincapacitating but nonfatal occurrence.

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CARDIOVASCULAR

CHAPTER 1:

ACUTE ISCHEMIC SYNDROMES


C–4 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

TRANSPORT CANADACARDIOVASCULAR

CHEST PAINChest pain, regardless whether typical or atypical forischemic heart disease, precludes medicalcertification insofar as it indicates an elevatedprobability of significant coronary artery disease andan increased risk of an incapacitating cardiac event.

An applicant may be considered fit if diagnostictesting indicates that the chest pain is not due tomyocardial ischemia. The initial assessmentincluding a review of the symptom history must bemade without the effect of anti-ischemic medicationsthat could possibly mask adverse findings. Ifcoronary arteriography reveals normal coronaryarteries, coronary vasospasm should be excluded.The presence of continuing symptoms of chest painin the absence of ischemia is not disqualifying per se;however, such symptoms must not be incapacitatingin any way.

FOLLOWING AN ACUTE ISCHEMICSYNDROME INCLUDING MYOCARDIALINFARCTIONAn acute ischemic syndrome is initially incompatiblewith medical certification. However, disqualificationis not necessarily permanent, and medicalcertification may be considered 6 months after theevent (a decision at 6 months must be based onrequisite assessments completed no sooner than 5months after discharge from hospital) provided thefollowing criteria are met:

• The result of an exercise test to a minimum effortof 8.5 METS (end of Stage 3) using the Bruceprotocol or equivalent places the individual atlow (<2%) risk of a significant cardiovascularevent over the following 12 months. Medicationsneed not be stopped for the test. If a perfusionexercise test is used, there should be nosignificant reversible defect and no large fixeddeficit as explained in the next point.

• The left ventricular ejection fraction as a measureof left ventricular function using echo-cardiography or gated radionuclide scintigraphy,is better than 50% at rest and does not show adecrease of more than 5% with satisfactoryexertion (i.e. 85% predicted maximum heart rateor > 8 METS). A threshold ejection fraction of45% applies with the use of SPECT (single protonemission computerized tomography) scanning.

• With a satisfactory ejection fraction as describedabove, Holter-monitoring is not required. For anejection fraction between 40% and 50%,restricted medical certification may beconsidered after review of a 24 hour Holter-monitor. This should reveal no more than 3ventricular ectopic beats per hour in the absenceof antiarrhythmic medication, with no more than3 consecutive beats and a cycle length that is notless that 500 msec.

• Major modifiable risk factors (see below ) forrecurrence of infarction are controlled, and theapplicant is a non-smoker.

A follow-up assessment a year after the infarctionand then annually should include a thorough history,physical examination, rest and exerciseelectrocardiography and a review of modifiable riskfactors. If there is no clinical deterioration after2 years, the treadmill exercise test can be done every2 years until the applicant is 50 years of age andsubsequently the possible need for yearly testingshould be considered.

These criteria apply regardless of whether theapplicant was treated for acute thrombosis e.g., witha thrombolytic drug, percutaneous coronaryintervention (PCI) or bypass surgery or theinfarction occurred in the presence of only mild tomoderate atheromatous disease as demonstrated byarteriography.


TRANSPORT CANADA


CARDIOVASCULAR

FOLLOWING REVASCULARIZATIONAn applicant who has been treated for coronaryartery disease by revascularization including bypasss u rg e r y, angioplasty with or without stenting,directional atherectomy etc., can be considered formedical certification after an interval of 6 months,provided the following criteria are met:

• The result of an exercise test to a minimum effortof 8.5 METS (end of Stage 3) using the Bruceprotocol or equivalent places the individual atlow (<2%) risk of a significant cardiovascularevent over the following 12 months.

• Patency of the revascularized artery ismaintained with no evidence of reversibleischemia on rest and exercise perfusion imaging.

• Major modifiable risk factors (see below) arecontrolled and the applicant is a non-smoker.

• Left ventricular function following bypasssurgery is satisfactory.

A follow-up assessment a year after therevascularization and then annually should include athorough history, physical examination, rest andexercise electrocardiography and a review ofmodifiable risk factors. If there is no clinicaldeterioration after 2 years, the treadmill exercise testcan be done every 2 years until the applicant is 50years of age and subsequently the possible need foryearly testing should be considered.

RISK FACTORS FOR ISCHEMIC HEARTDISEASEThe following are major modifiable risk factors forischemic heart disease. While many of them mayhave impressively large relative risks, their absoluterisk, particularly for sudden incapacitation, is low.Concern about these risk factors is greater inapplicants with known ischemic heart disease wherethe absolute risk is greater. The presence of majormodifiable risk factors should be a concern in anyapplicant and preventive measures are stronglyadvised.

Smoking

Prohibition of smoking in the cockpit should be thenorm for all flights of any duration. An applicant withknown ischemic heart disease who continues tosmoke should be assessed as “unfit”.

Increased serum cholesterol levels

All applicants are encouraged to be aware of theirserum cholesterol level and to maintain a normal level.Ta rget levels depend on the level of risk as outlined inthe Canadian Working Group Guidelines. Table 1.Total risk can be assessed on the basis of risk points forage, total and HDL cholesterol, systolic blood pressureand smoking status in the absence of existing coro n a ryh e a rt disease or diabetes. Table 2. The presence ofeither condition places the individual in a very highrisk level. All currently approved medications for lipidlowering are compatible with flying.

Table 1

Target Lipid LevelsLevel of Risk Target Values

DEFINITION LDL–C (MMOL/L) TC/HDL & RATIO TG & (MMOL/L)

VERY HIGH RISK

(10-yr risk >30% or historyof CVD or diabetes mellitus)

<2.5 <4 <2.0

HIGH RISK

(10-yr risk 20%-30%)<3.0 <5 <2.0

MODERATE RISK

(10-yr risk 10%-20%)<4.0 <6 <2.0

LOW RISK

(10-yr risk <10%)<5.0 <7 <3.0




Table 2

10–Year Absolute Risk of CVD EventRISK FACTOR MEN WOMEN SCORE

Age (years)

<3435-3940-4445-4950-5455-5960-6465-6970-74

-101234567

-9-40367888

__

Total cholesterol (mmol/L)

<4.144.15-5.175.18-6.216.22-7.24

>7.25

-30123

-20123

__

HDL cholesterol (mmol/L)

<0.900.91-1.161.17-1.291.30-1.55

>1.56

2100

-2

5210

-3

__

Systolic blood pressure (mmHg)

<120120-129130-139140-159

>1.60

00123

-30123

__

Smoker

NoYes

02

02

__

TOTAL RISK POINTS ____

RISK POINTS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

CHD MEN 3% 4% 5% 7% 8% 10% 13% 16% 20% 25% 31% 37% 45% 53%

RISK WOMEN 2% 3% 3% 4% 4% 5% 6% 7% 8% 10% 11% 13% 15% 18% 20% 24% >27%

* in individuals who have not had a prior CVD event.


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High Blood Pressure

The approach to the diagnosis of hypertensionfollows that of the Canadian HypertensionRecommendations Working Group. In licenceholders with accurately measured blood pressurelevels between 140 and 180 mmHg systolic and/or 90and 105 mmHg diastolic, at least four further visitsover 6 months are required to diagnose hypertension.However, in the presence of target organ damage,including coronary artery disease, LVH, LV systolicdysfunction, stroke, aortic and peripheral arterialdisease, hypertensive nephropathy (creatinineclearance < 1 mL/s) or retinopathy or asymptomaticatheroscelrosis, a diagnosis of hypertension can bemade at the third visit. The search for target organdamage can begin as early as the second visit.

If pressures remain at or above 160 mmHg systolic or100 mmHg diastolic, it is strongly recommended thatdrug treatment be initiated. It should also beconsidered when the diastolic pressure is between 90

and 100 mmHg. Medical certification can be grantedwhen treatment has been successful in reducing theblood pressure below 160 mmHg systolic and below100 mmHg diastolic, however the goal of bloodpressure control is less than 140/90 mmHg in mostindividuals including the elderly and to less than130/80 mmHg in those with diabetes or renaldysfunction. On any visit, a blood pressure level of180 mmHg or more systolic or 105 mmHg or morediastolic precludes medical certification.

Therapeutic Considerations

Recommended initial treatment now includesdiuretics, long acting dihydropiridine calciumchannel blockers and ACE inhibitors. Beta-blockersare included for those under 60 years of age whilealpha-blockers are not recommended as first-linetherapy. In licence holders, the major challenges withtreatment are to minimize postural hypotension, therisks of arrhythmias and adverse CNS effects.

Preferred drugs include:

1. ß-blockers: hydrophilic drugs are preferred (e.g. atenolol, nadolol, timolol).

2. Calcium channel antagonists: long-acting dihydropyridines are preferred (e.g. amlodipine, felodipine,nifedipine XL).

3. ACE-inhibitors: long-acting ACE-inhibitors are preferred such as ramipril, cilazapril, fosinopril,lisinopril, quinapril, etc.

4. Low dose diuretics: hydrochlorothiazide (< 25 mg/day) or potassium/ magnesium sparing diuretics suchas amiloride and spironolactone should be used

Acceptable drugs include:

1. ATII receptor blockers: candesartan, irbesartan, losartan, and others are similar to ACE inhibitors in theirhemodynamic action. They can be used singly or in combination. As with ACE inhibitors, ATII receptorblockers are acceptable in pilots who have been on one of these medications for a month or more withoutany adverse effects.

Drugs that are not permitted include:

1. Sympatholytics: guanethidine, most a blockers

2. High dose kaliuretic diuretics (> 25 mg hydrochlorothiazide or equivalent).

3. Clonidine and methyldopa (because of a risk of rebound hypertension if these medications areinadvertantly not taken).





Combination treatment, eg a low dose diuretic withan ACE inhibitor may be allowed particularly assmall doses of medications in combination may leadto fewer adverse effects than larger doses ofsingle agents.

Multiple Risk Factors

Coronary atherosclerosis is a multifactorial disease,the risk of early onset increasing with the number ofrisk factors present. Therefore in applicants theassessment of risk must weigh appropriately thecontribution of the various factors present. T h ecumulative risk conferred by the presence of morethan one risk factor, even at levels only moderatelyabove normal, can exceed that conferred by thepresence of one major risk factor alone. The presenceof only moderately elevated levels of risk when anyrisk factor is assessed alone should not lead to a falsesense of security on the part of the physician or theapplicant.

If the 10 year risk score is 20% or greater (9 riskpoints for men and 15 risk points for women, Table 2)or if diabetes or left ventricular hypertrophy arepresent, then a cardiovascular assessment includingan exercise treadmill test should be carried out.Additional tests will depend on the risk factor profile.If abnormalities are found, resulting in an averageannual mortality risk of 1% or more, assuming anadditional 1% risk of an incapacitating nonfatalevent, then a licence holder is considered unfit. Evenif the response to exercise testing is normal,appropriate therapy to modify risk factors should beinitiated.

Comments on Screening

Screening of the aircrew and air traffic controllerpopulation to identify cardiovascular disease beforesudden incapacitation is a problematic andcontroversial undertaking. On the one hand, the pilotmay feel harassed and unfairly burdened by theinconvenience and expense of screening tests. On theother hand, almost every accident involving suddenincapacitation that is suggestive of or attributed to acardiovascular cause brings impassioned publicappeals for more rigorous screening. It is beyond thescope of these guidelines to present the results ofanalyses that indicate the costs and problems ofwidespread routine screening. Nevertheless, arational policy toward screening can be adopted toprovide optimal, though never total, prevention ofcardiac incapacitation.

The current routine medical examination is intendedto ensure that only medically safe aircrew areallowed to fly. This is a shared responsibility with theonus on the applicant to report any symptoms and onthe physician to conduct a careful and thoroughexamination.

A resting electrocardiogram may show noabnormalities even in the presence of severe coronaryartery disease; in fact, this may be true in up to 50%of people with advanced coronary artery disease.Since the prevalence of ischemic heart diseaseincreases with age, the utility of routineelectrocardiography improves after age 50 and withthe presence of major risk factors for ischemic heartdisease. The current recommendations for routineelectrocardiographic testing which stratify thefrequency of testing by age are considered adequate.

Compared with a resting electrocardiogram, exerciseelectrocardiography increases the likelihood ofdetection of coronary artery disease. Widespreadintroduction of routine exercise testing is notadvisable because of concerns about inaccuracies inthe interpretation of test results as well as adverseeconomic and psychosocial consequences. T h epredictive value of a test result i.e. whether a testresult is truly positive or truly negative is influencedby the clinical characteristics of the personundergoing such testing. Routine screening of allapplicants by a treadmill exercise test will yield false-positive results more often than true-positive results.On the other hand, the number of true-positive resultsis increased significantly if such testing is appliedonly to those who are more likely to have coronaryartery disease, such as those with symptoms ofangina, those for whom major risk factors are presentand those in older age groups. Such a targetedapproach will not impose a major burden and willencourage adoption and maintenance of a hearthealthy lifestyle.


CHAPTER 2:

NON-ISCHEMIC HEART DISEASE

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CARDIOVASCULAR




VALVULAR HEART DISEASEThe significance of valvular heart disease dependsprimarily on the hemodynamic consequences,functional status and in some cases, the etiology. Inthe majority of cases, surgical correction will notreduce the risk of sudden incapacitation to acceptablelevels; in some cases it may even increase the risk.

Aortic Stenosis

Moderate or severe stenosis is unacceptable forunrestricted flying. Applicants with mild stenosis ofthe aortic valve can be considered for licensure if thefollowing conditions are met:

• The velocity flow across the valve is not less than3 m/sec.

• The cross-sectional valve area is not less than1.2 cm2, taking into account body size.

• There are no related symptoms.

• Holter monitoring reveals no significantdysrhythmia such as atrial fibrillation orsustained ventricular tachycardia.

• A satisfactory treadmill exercise test, achievingat least 8.5 METS (end of Stage 3) using theBruce protocol indicates no ischemia,hypotensive blood pressure response, significantarrhythmia or disabling symptoms.

Aortic Regurgitation

Pure isolated regurgitation is uncommon; therefore,assessment of applicants with aortic regurgitationwill likely include consideration of any associateddisorders. Only mild, asymptomatic aorticr e g u rgitation can be considered and only if thefollowing criteria are met:

• The pulse pressure is less than 70 mmHg and thediastolic pressure is greater than 65 mmHg.

• The end-diastolic internal diameter of the leftventricle is less than 57 mm taking into accountbody size, as measured by two-dimensionalechocardiography.

• A satisfactory treadmill exercise test, achievingat least 8.5 METS using the Bruce protocolindicates no ischemia, significant arrhythmia ordisabling symptoms.

Follow-up for Aortic Valve Disease

Because of the increased risk of endocarditis withaortic valve disease, prophylaxis with antibioticsmust be strictly followed. Follow-up should include ayearly assessment with at least 2-D and full dopplerechocardiography to monitor any progression.

Mitral Stenosis

In view of its progressive nature and its propensityfor thromboembolic complications, mitral stenosiswill disqualify most applicants. Only very mildmitral stenosis with a cross sectional mitral valvearea > 2.0 cm2 and stable normal sinus rhythm maybe considered.

Mitral Regurgitation

The cause of mitral regurgitation can alter theprognosis; therefore, an assessment of this conditionshould include information about the likelyunderlying cause, in addition to an estimate of theseverity of the lesion. Mild and asymptomatic mitralregurgitation may be acceptable in applicants if thefollowing conditions are met:

• Mitral stenosis is absent.

• The diameter of the left atrium is less than4.5 cm.

• Atrial dysrhythmia such as fibrillation or othersupraventricular tachycardia is absent, asdetermined by Holter monitoring.

• There is no history of embolism.

• Significant coronary artery disease is absentaccording to the results of a submaximaltreadmill exercise test.

Mitral Valve Prolapse

Mitral valve prolapse has a wide spectrum ofseverity. Most cases are mild and detectable either bythe presence of a midsystolic click and/or a softm u r m u r. The diagnosis is established bye c h o c a r d i o g r a p h y. Medical certification may beconsidered if the following conditions are met:

• There is no history of embolism or transientcerebral ischemia.

• There is no relevant family history of suddendeath.

• Left ventricular size does not exceed 60 mm.


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CARDIOVASCULAR

If the left atrial size is increased or if there isredundancy of the mitral valve leaflets, then atreadmill exercise test and 24 hour Holter-monitoringwill be required as these findings can be markers ofincreased risk.

Follow-up for Mitral Valve Disease

Annual follow-up for mitral valve stenosis and/orr e g u rgitation should include, in addition to athorough history and physical examination, 2D anddoppler echocardiography and 24 hour Holter-monitoring. The follow-up for mitral valve prolapsewill be determined on a case-by-case basis dependingon the degree of prolapse and any associatedfindings.

Surgical repair or replacement of valves

Following surgical reconstruction (valvuloplasty) ofthe mitral valve, a licence holder may be consideredfit to fly if an assessment after 3 months including anechocardiogram indicates no clinical or significantresidual hemodynamic abnormalities.

In view of the risk of thromboembolism, associatedcardiac dysfunction, valve failure and bleedingsecondary to anticoagulation, prosthetic valvularreplacement will disqualify most applicants. Such alevel of risk will preclude individuals with abioprosthetic mitral valve from flying. Where thecumulative risk of incapacitation due to these factorscan be shown to be less than 2% per year in thosewith a mechanical prosthesis and thus comparable tothe acceptable level of risk with other conditions, anapplicant may be considered fit.

Relatively recent surgical procedures including theRoss procedure and homograft valve replacementswill be considered on a case by case basis. Theformer requires a waiting period of at least 12 monthsto rule out pulmonary stenosis as a complication.

CONGENITAL HEART DISEASE

Atrial septal defect

Applicants with a patent foramen ovale or a smallsinus venosus or secundum defect (pulmonary/systemic flow ratio less than 2:1 and normal rightheart pressures) as determined by dopplerechocardiography or cardiac catheterization andwithout recurrent atrial arrhythmias need not berestricted from flying. Applicants with partialatrioventricular canal defects (primum type atrialseptal defects) cannot have more than mild mitral

r e g u rgitation, and they must meet the samerequirements for flow ratios and atrial arrhythmias.

Those who have undergone a transcutaneouscorrection or a surgical correction of a larger defectmay be medically certified if 3 months after theprocedure they meet the same requirements, providedthere has not been a significant event associated withtheir defect. A post-operative follow upechocardiographic evaluation is required todetermine the extent of any residual leakage andshunting.

Coarctation of the Aorta

Licence holders with surgically corrected coarctationof the aorta should be considered individually. Theage at the time of the surgical correction will be amajor determinant in the decision about medicalcertification of a licence holder since the risk ofsudden death and incapacitation due tocerebrovascular accidents is markedly increased inpeople who undergo surgery after the age of 12 years.In all cases the blood pressure at rest and in responseto exercise must be normal.

Pulmonary Stenosis

The major determinant of risk in applicants with thiscondition is the severity of the stenosis. Those withmild pulmonary stenosis and normal cardiac outputwill be considered for licensure provided thefollowing criteria are met:

• The peak systolic pressure gradient across thepulmonary valve is less than 50 mmHg, and thepeak systolic right ventricular pressure is lessthan 75 mmHg, as determined by echocardio-graphy or cardiac catheterization.

• Symptoms are absent.

• The result of a submaximal treadmill exercisetest is normal.

Applicants with pulmonic stenosis corrected bysurgery or balloon valvuloplasty will be consideredfit if there is no dysrhythmia and if the hemodynamicparameters are not worse than those described above.

Ventricular Septal Defect

An applicant’s eligibility for medical certificationwill depend on the size of the ventricular septaldefect as indicated by the hemodynamic conse-quences. In the absence of surgical correction anapplicant may be considered for licensure if thefollowing conditions are met:




• The heart size is normal.

• The pulmonary/systemic flow ratio is less than2:1, as determined by echocardiography orcardiac catheterization.

• The pressures in the right heart are normal.

An applicant with a surgically corrected ventricularseptal defect may be considered for medicalcertification if the same conditions are met as for nosurgical intervention, and in addition:

• No dysrhythmias or high-grade conductiondisturbances are detected by Holter monitoring.

• The response to a submaximal treadmill exercisetest is normal.

Tetralogy of Fallot

The unoperated condition with cyanosis isincompatible with medical certification. Individualswho undergo repair of Tetralogy of Fallot may beconsidered for medical certification if the followingconditions are met:

• Normal arterial oxygen saturation.

• Normal heart size.

• Right ventricular systolic pressure less than 75mmHg and peak RV/PA gradient less than 50mmHg.

• Residual interventricular shunt not more than1.5:1.

• No dysrhythmias or high-grade conductiondisturbances by Holter monitoring.

• Normal performance on a treadmill exercise test.

Transposition of Great Arteries

The unoperated condition is incompatible withmedical certification with the sole exception ofcongenitally corrected transposition without anyother associated cardiac abnormalities.

Applicants with atrial switch corrective proceduresfor transposition of the great arteries are unlikely tobe eligible for medical certification because of theincreasing propensity to atrial arrhythmias withpassing years, even with technically excellentsurgery. Applicants who have had arterial switchoperations will need to be considered separatelywhen this cohort begins to reach adulthood.

INFLAMMATORY HEART DISEASEActive pericarditis and/or myocarditis is medicallydisqualifying. Medical certification may beconsidered after satisfactory recovery with noadverse sequelae.

CARDIOMYOPATHYObstructive hypertrophic cardiomyopathy poses asignificant risk for sudden incapacitation andgenerally disqualifies an applicant from flyingregardless of whether there has been surg i c a ltreatment. Applicants with minor asymmetrichypertrophy will be considered individually based onthe degree of outflow obstruction and the nature ofany arrhythmias.

Nonhypertrophic cardiomyopathies dilated orcongestive, in their active phase disqualify anapplicant from flying. Symptomatic congestive heartfailure even with normal quantification of leftventricular function is incompatible with safepiloting. Cardiac catheterization is usually requiredto rule out ischemia as the etiology of thecardiomyopathy. Recertification may be consideredafter recovery if the following conditions are met:

• Symptoms are absent.

• A satisfactory exercise tolerance test achieving8.5 METS (end of Stage 3) using the Bruceprotocol indicates no ischemia, significantarrhythmia or disabling symptoms.

• Left ventricular function as determined byechocardiography is satisfactory, i.e. EF > 50%.An ejection fraction between 40% and 50% maybe acceptable for restricted flying provided 24hour Holter monitoring reveals no more than 3ventricular ectopic beats per hour in the absenceof antiarrhythmic medication, with no more than3 consecutive beats and a cycle length of not lessthan 500 msec. Nonsustained ventriculartachycardia in someone with an ischemiccardiomyopathy is not acceptable.

• The risk of thromboembolism and (if applicable)the risk of hemorrhage secondary toanticoagulation is acceptable.

CARDIAC TRANSPLANTATIONDue to the cumulative high rate of morbidityincluding vascular complications and the increasingmortality rate over time, cardiac transplantationdisqualifies an applicant from medical certification.


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CHAPTER 3:

DYSRHYTHMIAS


All applicants with dysrhythmias should be evaluatedwith two questions in mind: what is the nature of thedisability produced by a given arrhythmia i.e., howincapacitated is the applicant when the dysrhythmiaoccurs and what is the underlying condition of theheart i.e., is structural heart disease present. Bothquestions must be answered before a decision can bemade about an applicant’s fitness to fly.

SUPRAVENTRICULAR DYSRHYTHMIASSupraventricular tachydysrhythmias may accompanyself-limited illnesses e.g., pneumonia or treatableconditions e.g. hyperthyroidism. In such cases, theneed to restrict flying will be only temporary.

Applicants in whom treatment with an antiarrhythmicagent is successful need not be restricted from flying.Successful use of ablation therapy should beconfirmed with repeat electrophysiologic study 3months later in those individuals whose arrhythmiawas previously incapacitating. Applicants whoundergo AV nodal ablation of the slow pathway aremore likely to be reconsidered favourably because ofthe lower risk of development of heart block.

SINUS NODE DYSFUNCTIONIsolated sinus node dysfunction including sinusbradycardia may occur in healthy people, particularlythose involved in vigorous exercise programs. Such afinding (a consequence of high vagal tone) need notnecessarily be considered an abnormality. Providedthe dysfunction does not interfere with mentalfunction, the licence holder need not be restrictedfrom flying. Where there is concern e.g. extremebradycardia, a thorough symptom history should befollowed by Holter monitoring and a treadmillexercise test. Even in a healthy applicant, no R-Rinterval should exceed 4 sec during sleep or 3 secwhile awake.

ATRIAL FIBRILLATIONThere are 3 major concerns in the assessment of therisk of incapacitation in an individual with atrialfibrillation. The first is the hemodynamic effect of thearrhythmia itself. The second is the risk of embolismand the third is the risk of bleeding as a consequenceof anticoagulation. Since risk is additive, theaggregate risk must remain within acceptable limits.Therefore it is possible that flying may be allowed forselected aircrew depending on their condition and theeffect of treatment. The lowest risk is seen in thosebelow 65 years of age who have intermittent orchronic, lone atrial fibrillation, i.e. no identifiable

cause of the arrhythmia and no underlying structuralheart disease. Annual follow-up in such cases shouldinclude 24 hr Holter monitoring. Individuals withatrial fibrillation who have 2 or more of the 5 majorrisk factors, including age > 65 years, structural heartdisease, diabetes, high blood pressure and previousthromboembolism are considered to be above thethreshold level of risk even when fullyanticoagulated. Thus, older licence holders withstructural heart disease generally have a cumulativerisk of embolism and bleeding secondary toanticoagulation that exceeds the limit for medicalcertification.

PRE-EXCITATION SYNDROMESNot all cases of Wolff-Parkinson-White (the mostcommon type of pre-excitation) are associated withincapacitating dysrhythmias. The risk ofincapacitating symptoms in people who have neverhad tachycardia is low but is not known with anyprecision. Applicants with only anelectrocardiographic indication, whether chronic orintermittent, and no history of palpitations may be fitto fly if their response to a treadmill exercise test isnormal in all respects particularly if evidence of pre-excitation is lost at accelerated heart rates. Suchindividuals are unlikely to conduct at a dangerouslyhigh rate if in atrial fibrillation. Electrophysiologicstudies are not required in such cases.

Medical certification in a restricted capacity may beconsidered 3 months after a symptomatic episode oftachycardia has been controlled with medication.Applicants in whom accessory pathway connectionshave been ablated surgically or by cathetertechniques are considered fit if at 3 months they areasymptomatic and their electrocardiogram shows noevidence of pre-excitation. In some cases repeatelectrophysiologic studies may be required 3 monthsafter surgery to confirm a successful intervention.

VENTRICULAR DYSRHYTHMIASThe main concern with ventricular dysrhythmias isthe underlying condition of the myocardium. Acareful assessment should be done to determine thepresence of structural heart disease. If themyocardium is normal, ventricular ectopy should bejudged on the basis of the disability produced and, toa lesser extent, on the presence or absence ofcomplex forms. Although the complexity ofpremature ventricular beats is poorly correlated withrisk in the presence of normal myocardial tissue, theappearance of multiform or repetitive forms of




ventricular ectopy i.e., couplets, runs, should indicatethe need for a thorough cardiac examination sincethese and other high grade forms of ectopy are morecommonly seen in association with structural heartdisease. If the ventricular ectopic beats have a LBBBpattern particularly with a vertical axis, rightventricular dysplasia should be ruled out by eitherinvasive (ventriculography) or non-invasive (echo,MRI or radionuclide scintigraphy) tests.

The presence of more than 1 PVC on a resting 12-lead electrocardiogram warrants 24 hour Holtermonitoring.

Exercise-induced ventricular tachycardia can occurin healthy people. These events are usually self-terminating. Medical certification need not berestricted in such cases unless there are recurrentepisodes. Individuals with sustained tachycardiasare unfit.

CONDUCTION DISORDERSFirst-and-second-degree (type 1) atrioventricularconduction delay can be seen during rest (particularlysleep) in healthy people with a structurally normalheart who engage in vigorous exercise. High gradeatrioventricular block should be investigated to ruleout heart disease and to determine the risk ofprogression to complete heart block. Likewise firstand second-degree block with structural heart diseaseshould be investigated to determine the risk ofprogression to complete heart block.

BUNDLE BRANCH BLOCKLeft bundle branch block and right bundle branchblock of recent onset, indicate the need for acardiovascular examination to rule out heart disease,especially ischemic heart disease. Isolated rightbundle branch block and left hemiblocks that arelongstanding are generally benign.

CARDIAC PACEMAKERSThe reliability and safety of implantable cardiacpacemakers is well established and continues toimprove. Conditions in which there is little or nostructural heart disease and for which therequirements for a pacemaker are intermittent neednot disqualify a licence holder from flying. Each casewill need to be considered individually and notbefore 3 months after successful implantation.

Follow up requires a pacemaker clinic reportincluding an indication of the underlying rhythm andescape rate.

IMPLANTED CARDIAC DEFIBRILLATORSIt is highly improbable that an individual with animplanted cardiac defibrillator can be considered fit.However individual cases can be consideredprovided there is no structural heart disease and evenin such cases only a restricted medical certificationmay be granted. Such restricted certification will notbe considered before completion of a trial period of atleast 3 years. During this time defibrillator functionand cardiac response must be carefully monitored toensure that any dysrhythmias are properly identified,promptly corrected and that any episodes are notincapacitating.

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CARDIOVASCULAR


CHAPTER 4:

VASCULAR DISORDERS

TRANSPORT CANADA


CARDIOVASCULAR


ANEURYSMUntreated aneurysms, even if asymptomatic areunlikely to be compatible with medical certificationunless it can be demonstrated that the risk of ruptureis less than 2% per year. The presence of an aneurysme.g. in the abdomen of a middle-aged or older pilotraises concerns about the presence of co-existingconditions, particularly coronary artery disease.Prosthetic graft replacement of diseased aorticaneurysms with no other evidence of risk will beconsidered on an individual basis.

ASYMPTOMATIC CAROTID BRUITSince the presence of a carotid bruit may indicatesevere stenosis, it should lead to a carotid dopplerexamination. Likewise a cardiovascular assessmentis required to rule out significant coronary arterydisease. Significant stenosis (>75%) evenasymptomatic is associated with a >33% risk ofcoronary events over 4 years and therefore rendersthe applicant unfit. Any stenosis that has beenassociated with a stroke will also make theapplicant unfit.

ARTERIAL THROMBOSISIndividuals who have sustained an isolated, arterialthrombosis will be considered on an individual basis.Of particular concern are thromboses related tocoagulopathies or other chronic predisposingconditions.

VENOUS THROMBOSISAn isolated episode of deep venous thrombosis neednot preclude medical certification provided there areno chronic predisposing conditions, and a minimumof 3 months have elapsed since the episode.Applicants with recurring episodes or with knownpredisposing factors will be considered on anindividual basis only after 12 months have elapsedsince the last episode and their risk of recurrence islowered by satisfactory anticoagulation. In suchcases only short haul pilots on anticoagulation will beconsidered for a restricted category. The latterrequires demonstration of therapeutic INR levelsover a recent 1 month period.

PULMONARY EMBOLISMApplicants with an isolated episode of pulmonaryembolism, without predisposing conditions forrecurrence can be considered for relicensure after aninterval of 3 months, provided there is no disabling,residual pulmonary hypertension, right ventricularfunction is normal and the risk of venous thrombosisand pulmonary embolism is decreased by appropriatetreatment to an acceptable level.




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Bonow RO, Rosing DR, McIntosh CL, et al. Thenatural history of asymptomatic patients withaortic regurgitation and normal left ventricularfunction. Circulation 1983;68:509-517.

Dujardin KS, Enriquez-Sarano M, Schaff HV, et al.Mortality and morbidity of aortic regurgitation inclinical practice: a long-term follow-up study.Circulation 1999;99:1851-1857.

Padial LR, Oliver A, Vivaldi M, et al. Dopplerechocardiographic assessment of progression ofaortic regurgitation. Am J Cardiol 1997;80:306–314.

Turina J, Hess O, Sepulcri F, et al. Spontaneouscourse of aortic valve disease. Eur Heart J 1987;8:471-483.

Mitral Stenosis

Gordon SPF, Douglas PS, Come PC, et al. Two-dimensional and Doppler echocardiographicdeterminants of the natural history of mitral valvenarrowing in patients with rheumatic mitralstenosis: implications for follow-up. J Am CollCardiol 1992;19:968-973.

Horstkotte D, Niehues R, Strauer BE. Pathomorpho-logical aspects, aetiology and natural history ofacquired mitral valve stenosis. Eur Heart J 1991;12[Suppl B]:55-60.

Moreyra AE, Wilson AC, Deac R, et al. Factorsassociated with atrial fibrillation in patients withmitral stenosis: a cardiac catheterization study.Am Heart J 1998;135:138-145.

Olesen KH. The natural history of 271 patients withmitral stenosis under medical treatment. Br HeartJ 1962;24:349-357.

Ramsdale DR, Arumugam N, Singh SS, et al. Holtermonitoring in patients with mitral stenosis andsinus rhythm. Eur Heart J 1987;8:164-170.

Sagie A, Freitas N, Padial LR, et al. Dopplerechocardiographic assessment of long-termprogression of mitral stenosis in 103 patients:valve area and right heart disease. J Am CollCardiol 1996;28:472-479.

Selzer A, Cohn KE. Natural history of mitralstenosis: a review. Circulation 1972;45:878-890.

Mitral Regurgitation

Freed LA, Levy D, Levine RA, et al. Prevalence andclinical outcome of mitral-valve prolapse. N EnglJ Med 1999;341:1-7.

Gilon D, Buonanno FS, Joffe MM, et al. Lack ofevidence of an association between mitral-valveprolapse and stroke in young patients. N Engl JMed 1999;341:8-13.

Grigioni F, Enriquez-Sarano M, Zehr KJ, et al.Ischemic mitral regurgitation: long-termoutcome and prognostic implications withquantitative Doppler assessment. Circulation2001;103:1759-1764.




Kim S, Kuroda T, Nishinaga M, et al. Relationbetween severity of mitral regurgitation andprognosis of mitral valve prolapse: echocardio-graphic follow-up study. Am Heart J 1996;132:348-355.

Lamas GA, Mitchell GF, Flaker GC, et al. Clinicalsignificance of mitral regurgitation after acutemyocardial infarction. Circulation 1997;96:827–833.

Marks AR, Choong CY, Sanfilippo AJ, et al.Identification of high-risk and low-risksubgroups of patients with mitral-valve prolapse.N Engl J Med 1989;320:1031-1036.

Nishimura RA, McGoon MD, Shub C, et al.Echocardiographically documented mitral-valveprolapse: long-term follow-up of 237 patients.N Engl J Med 1985:313:1305-1309.

Zuppiroli A, Rinaldi M, Kramer-Fox R, et al. Naturalhistory of mitral valve prolapse. Am J Cardiol1995;75:1028-1032.

Pulmonary Stenosis

Hayes CJ, Gersony WM, Driscoll DJ, et al. Secondnatural history study of congenital heart defects:results of treatment of patients with pulmonaryvalvular stenosis. Circulation 1993;87[Suppl I]:I-28-I-37.

Prosthetic Valves

Fann JI, Burdon TA. Are the indications for tissuevalves different in 2001 and how do wecommunicate these changes to our cardiologycolleagues? Curr Opin Cardiol 2001;16:126–135.

Fann JI, Miller DC, Moore KA, et al. Twenty-yearclinical experience with porcine bioprostheses.Ann Thorac Surg 1996;62:1301-1312.

Glower DD, Landolfo KP, Cheruva S, et al.Determinants of 15-year outcome with 111 9standard Carpentier-Edwards porcine valves.Ann Thorac Surg 1998;66:S44-48.

Jamieson WR, Burr LH, Munro AI, et al. Carpentier-Edwards standard porcine bioprosthesis: a21–year experience. Ann Thorac Surg 1998;66:S40–43.

Park SZ, Reardon MJ. Current status of stentlessaortic xenografts. Curr Opin Cardiol 2000;15:74–81.

Puvimanasinghe JPA, Steyerberg EW, TakkenbergJJM, et al. Prognosis after aortic valvereplacement with a bioprosthesis: predictionsbased on meta-analysis and microsimulation.Circulation 2001;103:1535-1541.

Remadi JP, Baron O, Roussel C, et al. Isolated mitralvalve replacement with St. Jude medicalprosthesis: long-term results: a follow-up of19 years. Circulation 2001;103:1542-1545.

Stein PD, Bussey HI, Dalen JE, et al. Antithrombotictherapy in patients with mechanical andbiological prosthetic heart valves. Chest 2001;119:220S-227.

Vongpatanasin W, Hillis D, Lange RA. Prostheticheart valves. N Engl J Med 1996;335:407-416.

Aortic Allograft Replacement

Doty JR, Salazar JD, Liddicoat JR, et al. Aortic valvereplacement with cryopreserved aortic allograft:ten-year experience. J Thorac Cardiovasc Surg1998;115:371-380.

Kirklin JK, Smith D, Novick W, et al. Long-termfunction of cryopreserved aortic homografts: aten-year study. J Thorac Cardiovasc Surg 1993;106:154-166.

O’Brien MF, Stafford EG, Gardner MAH, et al.Allograft aortic valve replacement: long-termfollow-up. Ann Thorac Surg 1995;60:565-570.

Ross Procedure

Chambers JC, Somerville J, Stone S, et al. Pulmonaryautograft procedure for aortic valve disease:long-term results of the pioneer series.Circulation 1997;96:2206-2214.

Oury JH, Hiro SP, Maxwell JM, et al. The Rossprocedure : current registry results. Ann ThoracSurg 1998;66 :S162-165.

Stelzer P, Weinrauch S, Tranbaugh RF. Ten years ofexperience with the modified Ross procedure.J Thorac Cardiovasc Surg 1998;115:1091-1100.

Carr-White GS, Kilner PJ, Hon JKF, et al. Incidence,location, pathology, and significance ofpulmonary homograft stenosis after the Rossoperation. Circulation 2001;104[Suppl I]:I16-20.

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Transposition

Ikeda U, Kimura K, Suzuki O et al. Long-termsurvival in “corrected transposition. Lancet 1991;337:180-181.

Mitral Valve Repair

Bernal JM, Rabasa JM, Olalla JJ, et al. Repair ofchordae tendinae for rheumatic mitral valvedisease: a twenty year experience. J T h o r a cCardiovasc Surg 1996;111:211-217.

Braunberger E, Deloche A, Berrebi A, et al. Verylong-term results (more than 20 years) of valverepair with Carpentier’s techniques innonrheumatic mitral valve insuff i c i e n c y.Circulation 2001;104[Suppl I]:I8-11.

Chauvaud S, Fuzellier J-F, Berrebi A, et al. Long-term (29 years) results of reconstructive surgeryin rheumatic mitral valve insuff i c i e n c y.Circulation 2001;104[Suppl I]:I12-15.

Gillinov AM, Cosgrove DM, Blackstone EH, et al.Durability of mitral valve repair for degenerativedisease. J Thorac Cardiovasc Surg 1998;116:734–743.

Hausmann H, Siniawski H, Hotz H, et al. Mitralvalve reconstruction and mitral valvereplacement for ischaemic mitral insufficiency.J Cardiac Surg 1997;12:8-14.

Mohty D, Orszulak TA, Schaff HV, et al. Very long-term survival and durability of mitral valve repairfor mitral valve prolapse. Circulation 2001;104[Suppl I]:I1-7.

Obadia JF, Farra ME, Bastien OH, et al. Outcome ofatrial fibrillation after mitral valve repair.J Thorac Cardiovasc Surg 1997;114:179-185.

Yau TM, El-Thoneimi YAF, Armstrong S, et al.Mitral valve repair and replacement forrheumatic disease. J Thorac Cardiovasc Surg2000;119:53-61.

Percutaneous Mitral Balloon Valvuloplasty

Hernandez R, BaZuelos C, Alfonso F, et al. Long-term clinical and echocardiographic follow-upafter percutaneous mitral valvuloplasty with theInoue balloon. Circulation 1999;99:1580-1586.

Iung B, Garbarz E, Michaud P, et al. Late results ofpercutaneous mitral commissurotomy in a seriesof 1024 patients: analysis of late clinicaldeterioration: frequency, anatomic findings, andpredictive factors. Circulation 1999;99:3 2 7 2–3 2 7 8 .

Orrange SE, Kawanishi DT, Lopez BM, et al.Actuarial outcome after catheter ballooncommissurotomy in patients with mitral stenosis.Circulation 1997;95:382-389.

Palacios IF, Tuzcu ME, Weyman AE, et al. Clinicalfollow-up of patients undergoing percutaneousmitral balloon valvotomy. Circulation 1995;91:671-676.

Percutaneous Pulmonary Balloon Valvuloplasty

Chen CR, Cheng TO, Huang T, et al. Percutaneousballoon valvuloplasty for pulmonic stenosis inadolescents and adults. N Engl J Med 1996;335:21-25.

Jarrar M, Betbout F, Ben Farhat M, et al. Long-terminvasive and noninvasive results of percutaneousballoon pulmonary valvuloplasty in children,adolescents and adults. Am Heart J 1999;138:950-954.

Rao PS, Galal O, Patnana M et al. Results of three to10 year follow up of balloon dilation of thepulmonary valve. Heart 1998;80:591-595.

Sadr-Ameli MA, Sheikholeslami F, Firoozi et al. Lateresults of balloon pulmonary valvuloplasty inadults. Am J Cardiol 1998;82:398-400.

DYSRHYTHMIASCardiology Clinics: “Cardiac Arrhythmias and

Related Syndromes; Current Diagnosis andManagement” Ed.M. Akhtar, Volume II, Number1, February 1993, ppl-198, W.B. Saunders,Toronto.

Hirsh J. Guidelines for antithrombotic therapy(Summary of American College of ChestPhysicians Recommendations 1992) DeckerPeriodicals Inc.

Jackman WM, Beckman KJ et al. Treatment ofsupraventricular tachycardia due toatrioventricular nodal reentry by radiofrequencycatheter ablation of slow-pathway conduction. NEngl J Med 1992; 327:313-318.




Jackman WM, Wang X et al. Catheter ablation ofaccessory atrioventricular pathways (Wo l ff -Parkinson-White Syndrome) by radiofrequencycurrent. N Engl J Med 1991; 324:1605-1611.

NHLBI Working Group on Atrial Fibrillation.Current understandings and research imperatives.J Am Coll Cardiol 1993; 22:1830-1834.

VASCULAR DISORDERSChimowitz MI, Weiss DG, et al. Cardiac prognosis of

patients with carotid stenosis and no history ofcoronary artery disease, Stroke 1994; 25:759–765.

Ernst CB. Abdominal aortic aneurysm. NEJM 1993;328:1167-1172.

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DIABETES

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DIABETES

CANADIAN GUIDELINES FOR THE ASSESSMENTOF MEDICAL FITNESS IN PILOTS,

FLIGHT ENGINEERS AND AIR TRAFFIC CONTROLLERSWITH DIABETES MELLITUS

Dedicated to the Memory of Dr. Gerald S. Wong

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HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS D–1

DIABETES

Since the discovery of insulin in Toronto in 1923 byBanting & Best great progress has been made in thetreatment of diabetes mellitus. In the last ten yearscontrol of this condition has improved dramaticallywith the development of patient operated computerchip glucose meters and patient education. Bloodtests to assess long term control such as Hb.A1.C.also have made it much easier to make alterations todiet, exercise, insulin or hypoglycemic medicationdosage for optimum control.

This enormous progress in the management of thedisease together with an increase in the number ofinsulin and oral hypoglycemic treated diabeticsprompted Transport Canada’s Civil Av i a t i o nMedicine Branch to reexamine its policies ondiabetes mellitus. To this end a one day workshopwas held on April 8th 1992 in Ottawa to review thesubject in the context of the modern aviationenvironment.

These guidelines are based on the deliberations atthat meeting. Physicians are reminded that thisdocument should be used as a guide only and itshould not be confused with the medical standardsfor aviation personnel published by Transport CanadaAviation (TP 195). Any specific questions should bedirected tothe nearest regional aviation medicalo ffice of the Civil Aviation Medicine Branch,Transport Canada (Appendix).

To the late Dr. Gerald S. Wong, for his specialassistance in the early stages and for co-chairing theworkshop, I am eternally grateful.

To Dr. James Wallace, Senior Consultant, OperationsPolicy and Standards and to Dr. Robert Depuis,Internal Medicine Consultant to the Aviation MedicalReview Board, who shared the task of writing andediting the rest of this document, my gratitude forsuccessfully completing a very difficult task.

FOREWORD

G.Y. Takahashi, M.D., D.Av.Med.

Director, Civil Aviation Medicine Division (CAM)

Health Canada

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D–2 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

TRANSPORT CANADADIABETES

List of ParticipantsDR. GEORGE Y. TAKAHASHI

Director, Civil Aviation Medicine DivisionCAM, Ottawa

DR. JAMES M. WALLACE

Sr. Consultant, Operations, Policy and Standards,CAM, Ottawa,Co-Chairman

DR. ROBERT DUPUIS

Internal Medicine Consultant, Aviation Medical Review Board (AMRB) Ottawa,Co-Chairman

DR. GERALD S. WONG

Asst. Prof. Dept. of Medicine, University of Toronto, Co-Chairman

DR. MENG H. TAN

Prof & Head,Division of Metabolism & EndocrinologyDalhousie University, Halifax

DR. JEAN-FRANCOIS YALE

Asst. Prof. Department of Medicine,McGill University, Montreal

DR. JOHN DUPRE

Prof. Department of Medicine,University of Western Ontario, London

DR. STUART ROSS

Assoc. Prof. of Medicine,University of Calgary

DR. DAVID LAU

Assoc. Prof. Of Medicine,University of Ottawa

DR. ANDY WIELGOSZ

Consultant in Cardiology, AMRB,Assoc. Prof. of Medicine & EpidemiologyUniversity of Ottawa

DR. HYMAN RABINOVITCH

Consultant in Neurology, AMRB,Asst. Clinical Prof., University of Ottawa

DR. PAUL A. KING

Sr. Consultant Education & Training,CAM, Ottawa

DR. GUY SAVOIE

Chief Clinical Assessment,CAM, Ottawa

DR. STEPHEN V. BLIZZARD

Sr. Consultant, Safety,CAM, Ottawa

DR. BRIAN ST. L. LIDDY

Consultant in Ophthalmology,AMRB, Ottawa

DR. KENNETH BOYD

Regional Aviation Medical Officer,CAM, Pacific Region

DR. JENNIFER GEGG

Regional Aviation Medical Officer,CAM, Western Region

DR. JAMES NOLAN

Regional Aviation Medical Officer,CAM, Central Region

DR. BRENT HASKELL

Regional Aviation Medical Officer,CAM, Ontario Region

DR. FRANÇOIS DUBÉ

Regional Aviation Medical Officer,CAM, Quebec Region

DR. HART CORNE

Acting Regional Aviation Medical Officer,CAM, Atlantic Region

DR. WILLIAM DOUGHTY

Director, Medical ServicesCanadian Airlines International, Vancouver

DR. CLAUDE THIBEAULT

Director, Medical Services, Air Canada, Montreal

DR. WILLIAM HARK

Office of Aviation Medicine,Federal Aviation Administration,Washington, D.C. USA

DR. GARY GRAY

Defence and Civil Institute ofEnvironmental Medicine,Downsview, Ont.Medical Advisor to Canadian Airline Pilots A s s o c .

MR. HERBERT DROUIN

Executive Secretary,Canadian Diabetes Association, Ottawa

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DIABETES

IntroductionThe practice of aeromedical certification of pilots andair traffic controllers with diabetes in mostContracting States of the International Civil AviationO rganization, including Canada, has been fairlyconsistent and has not changed for many years.Applicants with diabetes whose condition can becontrolled by dietary measures alone are permitted tofly and control air traffic. All others requiringmedication for this common disorder are assessed as“unfit” for such activities.

The Canadian Charter of Rights and Freedoms whichwas enacted in 1982 has a number of human rightsprovisions, one of which states that “no person shallbe discriminated against on the basis of disability”.Given this constitutional background there have beenan increasing number of challenges in the Courts andHuman Rights Tribunals on refusals to issue licenceson medical grounds including diabetesmellitus (DM).

The Civil Aviation Medical Branch (CAM) ofTransport Canada is the medical body which advises

the Minister of Transport on medical fitness to fly orcontrol air traffic. CAM decided that the time hadarrived to review its position on all types of diabetes,given the apparent improvement in the treatment andcontrol of the disorder.

In order to address this issue, a conference wasconvened in Ottawa on April 8, 1992. Present at thisconference were six eminent specialists in DM,members of CAM headquarters and regional medicalstaff, members of the Aviation Medicine ReviewBoard (AB), medical representatives from the airlineindustry, the U.S. Federal Aviation Administrationand the Canadian Diabetes Association.

This document reflects the proceedings of that oneday conference.

The recommendations in this document maycause concern to some physicians, but it is felt thatwith the implementation of these re c o m m e n -dations meaningful data in this area can bedeveloped without jeopardizing flight safety.

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Guidelines

One of the major considerations in medicallycertifying diabetics who are insulin treated or whorequire oral hypoglycemics agents, is the risk ofsubtle or sudden incapacitation. In the diabeticperson this would be most likely caused byhypoglycemia. Let us therefore consider themetabolic condition of hypoglycemia.

HYPOGLYCEMIA:Hypoglycemia is usually considered to be a bloodglucose concentration in the range below the level atwhich symptoms could be expected to occur.

In the person without diabetes, blood glucose is keptwithin a fairly narrow range by a homeostaticmechanism regulated by glucose intake and storage,insulin, glucagon, catecholamines, cortisol andgrowth hormone. In insulin treated diabetes mellitus(ITDM) insulin is provided from an exogenoussource so fine control of this delicate homeostasis hasbeen compromised. Hypoglycemia may result fromtoo much insulin, too little glucose, anover–expenditure of energy or any combination ofthe above.

Diabetes specialists officially define hypoglycemiaas being either:

(a) when the plasma glucose falls below 2.8 mmol/L(50 mg./dl) or

(b) when symptoms of hypoglycemia occur.

The symptoms and signs of hypoglycemia can bebroken down into two main groups:

(a) Neurogenic• Weakness• Palpitations• Tremor• Sweating• Hunger

(b) Neuroglycopenic• Cognitive impairment• Mental status changes• Abnormal behaviour• Irritability• Seizure activity

Results from the multicentred Diabetes Control andComplications Trial revealed that among an intensiveinsulin treated group of patients with diabetes, theincidence of hypoglycemic reactions is relativelycommon. Severe hypoglycemia is definitely relatedto the degree of glycemia control and theeffectiveness of the physiological counter regulatorymechanisms.

Studies have also demonstrated that patients withdiabetes who are poorly controlled tend to recognizehypoglycemia at higher blood glucose levels than dointensively insulin treated diabetic individuals, whomay not recognize the hypoglycemic reaction untiltheir blood glucose level is much lower. This is aresult of blunting of the counter regulatorymechanisms. This situation which exists among theintensively treated group is termed by diabetologistshypoglycemia unawareness.

It is apparent then that the unpredictability ofhypoglycemia could be a major aviation safetyhazard in the cockpit or the air traffic controlworksplace.

As in many other areas of risk assessment in aviationmedicine, (e.g. cardiovascular, neurological), a levelat which the degree of risk can be consideredacceptable must be sought. This degree of risk shouldnot be much in excess of the risk of the samecondition occurring in a completely healthy person.Most recently in Canada, for conditions such ascoronary events or seizure following head injury, arisk of 2% per annum or less has been consideredacceptable.

Table 1 attempts to address the question of risk ofhypoglycemia. Those Insulin treated diabetics whofell into the high risk group would not be consideredfor any form of licence, whereas those falling in thelow risk group could be considered.

With this in mind the conference group has proposedthe following guidelines for the medical certificationof pilots, air traffic controllers and flight engineerswith diabetes. It must be understood that these areonly guidelines and that each case will be reviewedindividually by the Aviation Medicine Review Board.Of particular concern are the neuroglycopenic effectsof hypoglycemia and the effect they have oninformation processing, which is an extremelyimportant aspect of both piloting and air trafficcontrolling tasks.

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DIABETES

Table 1

HYPOGLYCEMIA RISK AMONG INSULIN USERS

HIGH RISK LOW RISK

• Previous hypoglycemic reactions requiringintervention

• Symptoms and signs of neuroglycopenia

• Unstable glycemia control as measured by:

(a) Glycated Hb (pt./upper norm ratio)(b) Blood glucose metering 10% values

< 5.5 mmol/L• Inadequate self monitoring

• Poor diabetes education and understanding

• Evidence of hypoglycemia unawareness

• Negative attitude to self care

• Stimulated C-peptide levels > 25% normal*

• No previous hypoglycemic reactions requiringintervention

• Stable control as measured by:(a) Glycated Hb (pt./upper norm ratio < 2.0)(b) Blood glucose metering 90% values

> 5.5 mmol/L• Adequate self monitoring with memory chip

glucose meter

• Good diabetes education and understanding

• No evidence of hypoglycemia unawareness

• Positive attitude to monitoring and self care

* C-peptide is an indicator of beta cell activity. Most IDDM’s are C-peptide negative.)

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6 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

DIABETES TRANSPORT CANADA


Non Insulin Treated Applicants WithDiabetes Mellitus (DM)

1. Those applicants who can control their bloodglucose by diet alone may be considered fit forall categories of licence, provided they have noc a r d i o v a s c u l a r, neurological, ophthalmologicalor renal complications of DM which could resultin sudden or subtle incapacitation whileexercising the privileges of their licence.

2. Applicants who require oral hypoglycemicagents to control their blood glucose may beconsidered for medical certification providingcertain criteria can be met.

These criteria are:

(a) No episode of hypoglycemia requiringintervention by others in past 12 months.

(b) The Applicants must have taken thehypoglycemic agent for a minimum of 6 months(3 months in the case of metformin and thethiolipinogones), and the dosage should havebeen stable for at least 3 months.

(c) There must be evidence of stable blood glucosecontrol for at least 3 months as measured by;

(i) Glycated Hb (patient/upper normal ratio lessthan 2.0)

(ii) Blood glucose metering shows 90% ofvalues greater than 5.5 mmol/L.

(d) No neurological, cardiovascular, ophthalmo-logical or renal complications of DM that couldresult in sudden or subtle incapacitation whileexercising the privileges of the licence.

(e) Blood glucose monitoring will be carried outusing a memory chip glucose meter. T h i sequipment together with a readily absorbablesource of glucose will be carried by the applicantwhile exercising the privileges of the licence.

(f) A vision care specialist assessment is required oninitial application and every year thereafter.

(g) A cardiovascular assessment to include anexercise electrocardiogram is required at the ageof 40 and then 5 yearly to age 50. After the age of50 it should be completed every two years. Aresting ECG will be required yearly.

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DIABETES


TRANSPORT CANADA

Insulin Treated Applicants WithDiabetes Mellitus (ITDM)

This group will include all Type I DM applicants andthose Type II DM applicants who require insulin inaddition to dietary management.

The major issue in this group, particularly in the TypeI (IDDM) applicants, is assessing the risk ofhypoglycemia. An attempt has been made based onthe opinions of the diabetologists at the conference toclassify low risk and high risk ITDM (see Table 1).

It is conceivable that an applicant who meets all thecriteria to be classified as low risk could beconsidered for a Category 4 (ultralight/glider) or aCategory 2 (ATC) medical certificate. (SeeAppendix I & II). All Category 2 applicants should

be referred to the Senior Consultant, Operationsi n Ottawa prior to a medical certificationrecommendation.

Until data has been gathered from the Category 2group (ATC) both in Canada and from otherjurisdictions, applicants for Category 3 with ITDMwill be considered unfit. An exceptionally low riskITDM who already holds a Category 1, may beconsidered for medical certification restricted to “asor with co-pilot”.

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Appendix 1STANDARD FOR CATEGORY 4

(Glider and Ultralight)

An u n s t a b l e metabolic disorder in the case ofdiabetes mellitus shall include any of the following.

• Any history within the past 2 years ofhypoglycemia requiring the intervention ofanother person or hypoglycemia in the absence ofwarning symptoms (hypoglycemicunawareness).

• Inadequate blood glucose control as indicated byblood glucose results or glycated hemoglobinresults.

• Significant visual, neurological or cardiovascularcomplications.

If an applicant with diabetes has none of the above,he/she may hold a Category 4 MC provided thefollowing requirements are also met:

(a) A full medical examination report, conducted bya designated CAME is submitted to the RAMO.

(b) A full report from a specialist in Endocrinology orInternal Medicine is submitted to the RAMO atfirst application and at yearly intervals thereafter.

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06_Diabetes 2004-03-12 10:47 AM Page 9

Appendix 2AIR TRAFFIC CONTROLLERS (ATCS)

Permission by special flexibility may be granted toATCs who have developed ITDM but are in the lowrisk group.

Glucose management during working hours:

All ITDM shall identify themselves as such to theshift supervisor. Individual ATCs with ITDM shallhave appropriate medical supplies available at alltimes in the workplace.

Supplies shall include:

• Blood glucose monitor with a memory chip.

• Blood sampling lancets.

• A source of readily absorbable glucose.

• Insulin with syringes or pump.

Blood glucose levels will be tested:

• 30 minutes prior to shift commencement.

• Every 2 hours during shift.

• If because of operational requirements the 2hourly blood glucose cannot be done then theindividual must consume at least 10 gm glucoseas a snack or drink.

• No two consecutive blood glucose estimationsmay be substituted by a snack.

• The shift supervisor should be given evidenceperiodically that blood glucose is well controlled.

PRECAUTIONS:If the blood glucose (BG) falls below 3.5 mmol/L,the individual shall stop work and take at least 10 gmof readily absorbable glucose. If at recheck within 30min., the BG is <5.5 mmol/L then further glucoseshall be taken until BG is 5.5 mmol/L or greater, atwhich time the individual may resume shift.

If BG is between 5.5 and 16.5 mmol/L no action isrequired.

If BG is between 16.5 and 22 mmol/L, takeappropriate action to lower BG. (i.e. with insulinand/or exercise). Recheck BG in 30 minutes.

If BG > 22 mmol/L then individual shall stop workand take corrective action (insulin), and then recheckBG every 30 minutes until BG < 22 mmol/L beforeresuming work. They should seek advice from aphysician.

If the controller experiences blurring of vision he/sheshould cease work and check BG.

• There should also be a set of instructions for shiftsupervisors.



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Appendix 3SELECTION CONDITIONS FOR INSULIN TREATED DIABETES APPLICANTS (ITDM)

– Cat. 4 R.P.P. & Student Pilot (Aeroplane) ITDMapplicants will be considered for medicalcertification provided the following conditionsare met:

• No recurring hypoglycemic episodes requiringthe intervention of another party during the past 5years.

• 1 year stable blood glucose control as measured by:

– glycated hemoglobin (A1 or A1 c l e v e l s )(patient/upper level normal ratio < 2.0)

– 90% blood glucose values > 5.5 mmol/L.

• Must demonstrate good diabetes education &understanding and have a positive attitudetowards monitoring & self control.

• No evidence of hypoglycemia unawareness.

• Medical evaluation by a specialist in diabetesevery 3 months, to include glycated hemoglobin(A1 or A1c levels) levels and a log of bloodglucose levels.

• The initial medical report should includespecialist reports from:

*a) an ophthalmologist*b) a cardiologist (to include a Tr e a d m i l l

Exercise Test – TXT)*c) a neurologist*d) a nephrologist

All of these reports should be negative in terms ofsignificant complications of diabetes.

• Submission of a routine civil aviation medicalexamination report including a resting ECG at noless than 12 monthly intervals.

• A report from a vision care specialist every2 years.

• A report from a cardiologist (to include a TXT)every 2 years over the age of 40.

Note: All ITDM applicants who have achievedmedical certification will be monitored by asingle physician within the CAMorganization in order to maintain consistencyand an adequate data base.

* Reports a, b and c may be in the form of ac o m p rehensive re p o rt from a specialist ininternal medicine.

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Appendix 4SELECTED ITDM APPLICANTS WHO MEET CATEGORY 4 R.P.P., STUDENT PILOT &

CATEGORY 1R AIRLINE TRANSPORT PILOT LICENCE (ATPL) (AEROPLANE)MEDICAL CERTIFICATION CONDITIONS

Blood Glucose Management Prior toand During Flight

Note: Blood Glucose levels will be required to bemaintained at higher than optimal valuesprior to and during flight, in order tominimize the risk of hypoglycemia. Thismay have an effect on the long term health ofthe individual. The applicant must be madefully aware of this.

1. Individuals with ITDM shall maintain theappropriate supplies for blood glucosemanagement, which shall include:

(a) A reliable calibrated glucose meter withmemory chip and appropriate bloodsampling equipment.

(b) A supply of 10 gm. portions of readilyabsorbable carbohydrate, appropriate to theduration of flight.

2. Prior to flight blood glucose must be greater than6.0 mmol/L. Blood glucoses must be monitoredevery 30 minutes during flight. If the bloodglucose falls below 6.0 mmol/L then 10 gms.carbohydrate should be ingested.

3. If, for operational reasons, the in-flight 30 minuteblood glucose measurement cannot be done, then10 gms. carbohydrate must be ingested, however,this shall not be done on two consecutive30 minute occasions without a blood glucosemeasurement.

4. The blood glucose should be measured30 minutes prior to landing and if below 6.0mmol/L then 10 gms. carbohydrate must beingested.

5. If the blood glucose should exceed 15 mmol/Lthen the individual should land as soon aspossible and take corrective therapeuticmeasures.



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ASTHMA

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HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS A–1

ASTHMA

Guidelines on the

Aeromedical Assessment of Asthma

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A–2 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS

TRANSPORT CANADA

PREAMBLEAsthma is a disorder characterized by increasedresponsiveness of the small airways to variousa l l e rgens and non-specific stimuli resulting inwidespread airways inflammation and reflexnarrowing of the airways. It has a wide clinicalspectrum varying from a single short-lived episode,requiring little or no medication to that of a constant,disabling condition requiring a combination oftherapeutic agents. It’s course and severity can bequite predictable in most, albeit less predictable insome. Sudden incapacitation is not a rarephenomenon and may pose a threat to aviation safety.

AEROMEDICAL SIGNIFICANCE

• Acute asthma attacks may cause partial (orcomplete) incapacitation in the cockpit (or airtraffic control workplace).

• Acute asthmatic attacks may be precipitated inflight by the inhalation of fumes such as mightoccur in engine or electrical fires or from otheragents which could act as bronchial irritants.

• In severe asthmatics, particularly after a recentattack , actual pulmonary function may be worsethan that determined from simple clinicalexamination. Consequently, hypoxia, asmeasured by oximetry, may devela at loweraltitudes than normal. A humid environment andhigh pollen counts that may be encounteredduring low altitude flight can exaggerate airwayresponsiveness and predispose to more severeasthma attacks. Air trapping in chronic asthmacan present an increased risk of barotrauma inhigh altitude flight, particularly if suddendecompression should occur.

P R O TO C O L FOR THE ASSESSMENT OF RISKThe applicant who discloses a diagnosis of asthmashould be assessed against the subjective andobjective criteria outlined below, and, whennecessary, such applicants should be referred to arespirologist or specialist in internal medicine with aninterest in respiratory medicine, for a more precisedetermination of the diagnosis, severity, treatment,and prognosis.

SUBJECTIVE CRITERIA• age of onset;• nature of symptoms, past and present;• present medication regime, any recent change,

and reason for change;• duration of present therapy;• compliance with therapy;• side effects of therapy (if any);• active smoking history;• and reaction to passive smoke.

CRITICAL CRITERIA• number of emergency room visits in the last five

years;• number of hospitalizations in the preceding five

years;• ataia in childhood;• use of steroids, oral or IV;• severity of exacerbations: ICU admission,

intubation requirement;• and length of recovery following exacerbation.

OBJECTIVE CRITERIA• evidence of bronchospasm, dyspnea, chest

hyperinflation;• other ancillary features of asthma: nasal polyps,

rhinitis, eczema pulmonary function tests.

1. The most sensitive tests are the FEV1 (ForcedExpiratory Volume in one second ) and MMFR(Maximum Midexpiratory Flow Rate).

2. Results below predicted normal for age should bequestioned.

3. Results below 70% predicted, indicates a moreserious problem.

4. Response to ß-adrenergic challenge – better orequal to 12%, and more than a 200cc change inFEV1.

Note: The decision to refer to a specialist should bebased on discussions with the RAMO/AMO.Decisions concerning the use of themethacholine challenge tests should be madeby the attending specialist.


ASTHMA

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MEDICATIONS AVAILABLE FOR ASTHMATREATMENT

S h o rt acting ß2 agonists (SABA): ( t e r b u t a l i n e ,salbu-tamol, albuterol)

• drugs of choice for relief of acute symptoms andfor short-term duration.

• used for prevention of exercise inducedbronchospasm.

• side effects may include tremor, nervousness andtachycardia.

Long acting ß2 agonists (LABA): ( f o r m o t e r o l ,salmeterol)

• Add-on therapy to inhaled steroids (see CanadianAsthma Consensus Report).

• Or can be used as a SABA ( p a r t i c u l a r l yformoterol) for PRN use.

Methylxanthines (aminahylline)

• rarely used these days for asthma. If used,question its use.

• have a narrow therapeutic range.• potential for severe side-effects including cardiac

arrhythmias, tremor and may induce convulsivedisorders.

Leukotriene re c e p t o r antagonists (zafirlukast,montelukast)

• anti-inflammatory agent as “add-on” to steroidtherapy in asthma.

• no side effects.• their role in asthma is limited and response rate

not predictable (30% of patients will do well onthese agents).


ASTHMA

Table 1

LEVELS OF ASTHMA SEVERITYBASED ON TREATMENT

NEEDED TO OBTAIN CONTROL

AsthmaSeverity Symptoms Therapy

Required

Very Mild Well controlledNone, or

inhaled SABA

Mild Well controlledInhaled SABA+ low dose ICS

Moderate Well controlledSABA + ICS +LABA or other

Rx additions

SevereMay or maynot be wellcontrolled

As above +oral steroids

Table 2

MEASURES OF ASTHMA SEVERITY

SEVERITY OF ASTHMA

Event orMeasurement Mild Moderate Severe

FEV1, or PEF,% of predicted

>80% 60-80% <60%

Need forinhaled SABA

Every 8 ormore h

Every4-8 h

Every2-4 h

Probability of:

Previous nearfatal episode

0 0 0+

Recentadmission to

hospital0 0 0+

Night timesymptoms

0 to + + +++

Limitation ofdaily activities

0 to + ++ +++

Note: FEV1 = forced expiratory volume in1 second;

PEF = peak expiratory flow

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Inhaled gluco-corticosteroids: (ICS) (fluticasone,budesonide, beclomethasone)

• highly effective and predictable asthmastabilizers.

• infrequent clinically important side-effects (mostoften taical).

• used in all stages of asthma.• combination therapy with a LABA n o w

available.

ASTHMA

Figure 1

CONTINUUM OF ASTHMA MANAGEMENT

The above diagram is from the Canadian Asthma Consensus Report, 1999.


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ASTHMA

RECOMMENDATIONS1. All Categories-Initial Applicants

When there is a significant history of asthma( e m e rgency room visits within the past twoyears) or when medication usage to prevent/treatairways inflammation and bronchospasm is inexcess of the “mild” criteria in the Tables above),the applicant should be referred to a specialist forclinical assessment including an objectiveappraisal of asthma through pulmonary functiontests (usually spirometry, flow-volume loa,bronchial challenge and at times a study ofresidual volume, oximetry, etc).

2. Initial or Renewal Applicants

(i) Very mild and mild asthma by clinical or‘challenge’ *definition may be acceptable forCategory 1, 2, 3 or 4 if symptoms are wellcontrolled by daily inhaled steroids oroccasional aerosol bronchodilators.

(ii) Moderate asthma should be referred to theAviation Medical Review Board (AMRB) fora recommendation. All cases referred to theAMRB should have the apprariate specialist’sreport. A “restricted” category may beconsidered for renewal candidates only.

(iii) Severe asthma is disqualyifing for allcategories of medical certification

* Methacholine challenge of 2.0 mg/ml or higher.3. Follow-up for all but “mild” applicants A n

annual specialist report to include PFTs at thediscretion of the specialist.

Note: Any increase in the severity of the asthmawill necessitate reevaluation.

4. The use of SABA /LABA should be restricted toeight hours or more prior to flying, but may beused in an unusual asthmatic attack in flight toallow the safe completion of the flight.

REFERENCESCanadian Asthma Consensus Report, 1999.

Supplement to CMAJ 1999; 161 (11 Suppl)

SPECIAL THANKS TODRS JOCELYN DENEAULT AND ANDRÉ PELOQUIN


ASTHMA

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OTHER POLICES

08_Other Policies 2004-03-12 10:49 AM Page 1

EAR, NOSE AND THROAT

1. Hearing:

Audiogram if doubt raised by screeningexamination. Acceptable limits:

35 db at 500 Hz1000 Hz2000 Hz

50 db at 3000 Hz

If hearing doesn’t meet standard on audiogramthe applicant will likely need Practical HearingTest.

2. Drum Perforation:

A single dry perforation is acceptable. An acuteperforation will result in being unfit until hearingand the tympanic membrane recovers.

3. Otitis media:

Unfit until recovered

4. Sinusitis:

Unfit until recovered.

5. Menière’s Disease:

Disqualifying. ENT consult will be needed toconfirm diagnosis.

6. Labyrinthitis:

Unfit while acute. ENT consult will be needed innon-infective vestibular disorders.

OPHTHALMOLOGY

1. Myopia:

Initial medical Category 1,2 or 3 - need glassesprescription if uncorrected visual acuity is 6/60(20/200) or worse.

2. Cataracts:

Unfit when vision in affected eye no longermeets standard.

3. Intraocular Lenses:

Unfit for 6 weeks following surgery. Full reportfrom attending ophthalmolgist.

4. Colour Vision Deficiency:

If applicant fails pseudoisochromatic plate test,he will be given restricted medical certificate(Daylight only, 2 way radio required at controlledairports). Those who fail plate test may try acolour lantern test or Farnsworth D-15.

5. Contact Lenses:

Can be approved for all categories:

6. Refractive Surgery:

(See guidelines on Page OP–3)

RESPIRATORY

1. Pneumonia:

Unfit until fully recovered.

2. COPD / Emphysema:

Usually disqualifying if it requires activetreatment. Pulmonary function tests and arterialblood gases or oxymetry usually required.Consultation with a respirologist or internist isusually required.

3. Asthma:

(See guidelines on Page A–1.)

GASTROINTESTINAL DISEASE

1. Acid Peptic Disease:

Dyspepsia or esophagitis treated with antacidsalone is acceptable. Long term maintenance withH2 antagonists is acceptable if there are nosignificant side - effects.

2. Gastric / Duodenal Ulcer:

Disqualifying while ulcer is present and underactive treatment. Long term maintenance withH2 antagonists is acceptable if no significant side- effects.

3. Hernia:

Significant hernias are disqualifying until thehernia is repaired. If there is any question aboutthe significance of a hernia a surg i c a lconsultation is required.

TRANSPORT CANADA

HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS OP–1

OTHER POLICIES


4. Cholelithiasis / Cholecystitis:

Cholecystitis is disqualifying. Presence of stoneswith a history of symptoms is disqualifying.Asymptomatic cholelithiasis as an incidentalfinding may be acceptable.

GENITOURINARY DISEASE

1. Renal Calculi:

Single episodes my be acceptable after recoveryif IVP or ultrasound shows no stones present, anda metabolic work-up is normal. Repeatedepisodes will need a full work-up and individualassessment.

2. Cancer of the Prostate:

May be acceptable after treatment. Will need fullreport from urologist or oncologist. Follow-upreports including PSA will likely be required.

METABOLIC DISEASE \

1. Diabetes Mellitus: (See Section D1 -D10.)

2. Thyroid Disorders:

Hypothyroidism is acceptable if adequatelytreated and stabilized. Hyperthyroidism requiresfull report from internist or endocrinologist andtreatment stabilization prior to assessment.

MUSCULOSKELETAL DISEASE

1. Locomotor Dysfunction:

Includes all amputations, malformation, arthritisand loss of function. All will be assessed on anindividual basis. Full description is required.Practical Flight Test may be required.

PSYCHIATRIC DISEASE

1. Anxiety Disorder:

Disqualifying if requiring active treatment withtranquilizers. Will likely require a psychiatricconsultation.

2. Depression:

Ongoing depression is disqualifying condition.May be recertified after full recovery andcessation of treatment. Waiting period prior torecertification will be individually assessed.Report from attending physician or psychiatristlikely required.

Note: Applicants who have been treated for adepressive illness and who are onmaintenance or prophylactic therapy withnon-sedating selective serotonin reuptakeinhibitors (SSRIs) may be considered formedical certification on an individual basisafter review by the CAM Aviation MedicineReview Board.

3. Substance Abuse / Dependence:

Disqualifying. Once “recovering”, an individualassessment to assess risk of relapse. Restrictedcategory may be recommended. Continuedabstinence is the key to medical recertification.

MALIGNANCY

1. Malignancy:

Each case assessed individually. A c t i v echemotherapy is disqualifying. Will need:pathology report and report from oncologist toinclude staging, treatment, prognosis and follow- up plans.

HIV /AIDS

1. Applicants who are HIV seropositive may beconsidered for medical certification on anindividual basis. The major concern is the devel-opment of HIV related psychiatric or neuro-logical complications. CD-4 cell counts and “viralload” measurements will be taken into account.For further information contact your RAMO.

OP–2 HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS



REQUIREMENTS FORMEDICAL CERTIFICATION FOLLOWING

REFRACTIVE SURGERY

Prior to medical certification after corneal refractive surgery the following conditions must be met. Theseconditions apply to all medical categories and to initial and subsequent treatments. The emphasis is on the stabilityof vision and refraction.

PHOTOREFRACTIVE KERATECTOMY (PRK) AND LASER ASSISTED IN-SITU KERATOMEULESIS(LASIK)

• Minimum intervals between withdrawal of eyedrops after refractive surgery and medicalcertification for pre-operative refractive error of :

Up to 6.00 Dioptres spherical equivalent:PRK – 3 monthsLASIK – 3 months

6.00 to 10.00 Dioptres spherical equivalent:PRK – 6 monthsLASIK – 3 months

Greater than 10.00 Dioptres spherical equivalent:PRK – 6 monthsLASIK – 6 months

• Visual acuity which meets the required standards

• No “haloing”, haze or night vision problems

• Refraction and visual acuity remaining stable, asdemonstrated by refraction and visual acuitymeasurements at 3 and 6 months post-surgery

• No significant reduction in contrast sensitivitymeasurements

• No ongoing medical treatment of the eyes

• Completion of a specific questionnaire by avision care specialist

• Follow-up report by a vision care specialist 12months after medical certification.

• RADIAL KERATOTOMY (RK)

• Minimum intervals between withdrawal of eyedrops after refractive surgery and medicalcertification for pre-operative refractive error of :

Up to 6.00 Dioptres spherical equivalent:3 months

6.00 to 10.00 Dioptres spherical equivalent:6 months

Greater than 10.00 Dioptres spherical equivalent:6 months

• Visual acuity which meets the required standards

• No haze or night vision problems

• Refraction and visual acuity remaining stable, asdemonstrated by refraction and visual acuitymeasurements at 3 and 6 months post-surgery

• No significant diurnal variation in visual acuity

• No ongoing medical treatment of the eyes

• Completion of a specific questionnaire by avision care specialist

Note: In selected cases, applicants can return todaylight flying or ATC duties after 1 month,provided the Ophthalmologist has confirmedgood stable results without complications.

NOVEMBER 2003

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OTHER POLICIES


P H O TOREFRACTIVE KERAT E C TO M Y ( P R K )and LASER ASSISTED IN SITU

KERATOMEULESIS (LASIK)

PATIENT’S NAME: _________________________ FILE No. ___________________________________Date of Surgery: _____________________________ Surgical Technique: ___________________________

Number of treatments: ________________________ Size(s) of Ablation Zone(s): _____________________

UNCORRECTED ACUITY REFRACTION & CORRECTED ACUITY

Pre-operative data:

OD __________ _____________________ = _____________________

OS __________ _____________________ = _____________________

3 Months Post PRK:(may be completed by an Optometrist)

OD __________ _____________________ = _____________________

OS __________ _____________________ = _____________________


OD __________ _____________________ = _____________________

OS __________ _____________________ = _____________________

Are there any of the following:

Glare sensitivity or “haloing” . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Night vision difficulty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Diurnal variation of vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Use of ocular medication . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . Yes _____ No _____

Corneal haze . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Loss of contrast sensitivity/acuity (this has potentiallyserious implications in the aviation environment) . . . . . . . . . . . .Yes _____ No _____

Signature of attending Ophthalmologist/ Optometrist ____________________________________________

Date: ______________________________ Phone: ( ) ________________________________

MAY 1999




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OTHER POLICIES

RADIAL KERATOTOMY (RK)

PATIENT’S NAME: _________________________ FILE No. ____________________________________Date of Surgery: _____________________________ Surgical Technique: ___________________________

Number of treatments: ________________________

UNCORRECTED ACUITY REFRACTION & CORRECTED ACUITY KERATOMETRY

Pre-operative data:

OD __________ _____________________ = _____________________ _______________

OS __________ _____________________ = _____________________ _______________


OD __________ _____________________ = _____________________ _______________

OS __________ _____________________ = _____________________ _______________


OD __________ _____________________ = _____________________ _______________

OS __________ _____________________ = _____________________ _______________


OD __________ _____________________ = _____________________ _______________

OS __________ _____________________ = _____________________ _______________

Are there any of the following:

Glare sensitivity or “haloing” . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Night vision difficulty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Diurnal variation of vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Use of ocular medication . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . Yes _____ No _____

Corneal haze . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes _____ No _____

Signature of attending Ophthalmologist/ Optometrist ____________________________________________

Date: ______________________________ Phone: ( ) ________________________________

MAY 1999


AERONAUTICS ACT (1985)

MEDICAL AND OPTOMETRIC INFORMATIONMinister to be provided with information

6.5 (1) Where a physician or an optometrist believeson reasonable grounds that a patient is aflight crew member, an air traffic controlleror other holder of a Canadian aviationdocument that imposes standards of medicalor optometric fitness, the physician oroptometrist shall, if in his opinion the patienthas a medical or optometric condition that islikely to constitute a hazard to aviationsafety, inform a medical adviser designatedby the Minister forthwith of that opinion andthe reasons therefor.

Patient to advise

(2) The holder of a Canadian aviation documentthat imposes standards of medical oroptometric fitness shall, prior to any medicalor optometric examination of his person by aphysician or optometrist, advise thephysician or optometrist that he is the holderof such a document.

Use by Minister

(3) The Minister may make such use of anyinformation provided pursuant to subsection(1) as the Minister considers necessary in theinterests of aviation safety.

No proceedings shall lie

(4) No legal, disciplinary or other proceedingslie against a physician or optometrist foranything done by him in good faith incompliance with this section.

Information privileged

(5) Notwithstanding subsection (3), informationprovided pursuant to subsection (1) isprivileged and no person shall be required todisclose it or give evidence relating to it inany legal, disciplinary or other proceedingsand the information so provided shall not beused in any such proceedings.

Deemed consent

(6) The holder of a Canadian aviation documentthat imposes standards of medical oroptometric fitness shall be deemed, for thepurposes of this section, to have consented tothe giving of information to a medicaladviser designated by the Minister undersubsection (1) in the circumstances referredto in that subsection.




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CONTACTS

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Civil Aviation Medicine Branch Offices

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HANDBOOK FOR CIVIL AVIATION MEDICAL EXAMINERS CON–I

CONTACTS

HEADQUARTERS

Civil Aviation MedicineTransport Canada330 Sparks St.Place de Ville, Tower “C”, Room 617Ottawa, OntarioK1A 0N8

Telephone: (613) 990-1302 (General)Facsimile: (613) 990-6623E-mail: [email protected]

ATLANTIC REGION

New Brunswick, Nova Scotia,Prince Edward Island, Newfoundland and Labrador

Civil Aviation MedicineTransport Canada330 Sparks St.Place de Ville, Tower “C”, Room 617Ottawa, OntarioK1A 0N8

Telephone: (1-888-764-3333)Facsimile: (613) 990-6623E-mail: [email protected]

QUEBEC REGIONQuebec

Civil Aviation MedicineTransport Canada700, Leigh Capreol, Room 2007ADorval, PQH4Y 1G7

Telephone: (1-888-570-5712)Telephone: (514) 633-3258 (General)Facsimile: (514) 633-3247E-mail: [email protected]

ONTARIO REGIONOntario

Civil Aviation MedicineTransport Canada300-4900 Yonge St.North York, OntarioM2N 6A5

Telephone: (1-877-726-8694)Telephone: (416) 952-0562 (General)Facsimile: (416) 952-0569E-mail: [email protected] mailto:

PRAIRIE & NORTHERN REGIONAlberta, Yukon, Manitoba, Saskatchewan,Northwest Territories and Nunavut

Civil Aviation MedicineTransport Canada1140-9700 Jasper Ave.Edmonton, ABT5J 4C3


PACIFIC REGIONBritish Columbia

Civil Aviation MedicineTransport Canada600-800 Burrard St., Room 620Vancouver, BCV6Z 2J8


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