Thursday Cme Presentation

8/7/2019 Thursday Cme Presentation

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ANG CHIA MIN

Laryngoscopy and TrachealIntubation in the Head-

Elevated Position in ObesePatients: A Randomized,Controlled, Equivalence Trial


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2008; 107:1912-1918

Laryngoscopy and Tracheal Intubation in theHead-Elevated Position in Obese Patients: A

Randomized, Controlled, Equivalence Trial

Srikantha L. Rao, MBBS, MS*, Allen R. Kunselman,

MA, H. Gregg Schuler, MS, CCRC, and Susan

DesHarnais, PhDFrom the *Department of Anesthesiology, Office of the Vice

Dean for Research and Graduate Studies, andDepartment of Public Health Sciences, PennsylvaniaState University, College of Medicine, M.S. Hershey

Medical Center, Pennsylvania.


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INTRODUCTION

Excellent intubating conditions are imperative fordirect laryngoscopy and the efficient placementof a tracheal tube.

The proper positioning of a patient beforeinduction is a key step.

Classic teaching has been to position the patientin the "sniffing" position, or supine with moderate

head elevation and atlanto-occipital extension.

Bannister FB, Macbeth RG. Direct laryngoscopy and tracheal intubation. Lancet1944;244, 6325:6514


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OBESE vs NORMAL WT PT

some studies have reported that trachealintubation is more difficult in obese as comparedto normal weight patientsLinksJuvin P, Lavaut E, Dupont H, Lefevre P, Demetriou M, Dumoulin JL, Desmonts JM. Difficulttracheal intubation is more common in obese than in lean patients. Anesth Analg 2003;97:595600

Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normalpatients: a meta-analysis of bedside screening test performance. Anesthesiology 2005; 103:42937

Other studies have reported no differencebetween the two groups, attributed it to a rampedposition with the patient's head clearly elevated

above their shoulders to improve laryngealexposure in obese patients.

Levitan RM, Ochroch AE. Airway management and direct laryngoscopy: a review and update. CritCare Clin North Am 2000;16:37388

Brodsky JB, Lemmens HJ, Brock-Utne JG, Vierra M, Saidman LJ. Morbid obesity and trachealintubation. Anesth Analg 2002; 94:7326


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Head up vs supine sniff position

In a randomized study with a crossover design of 40 non-obese patients, significantly improved laryngeal view was

demonstrated by performing laryngoscopy in the 25-

degree head-up position compared to the supine position

in the same patients.Lee BJ, Kang JM, Kim DO. Laryngeal exposure during laryngoscopy is better in the 25

degrees back-up position than in the supine position. Br J Anaesth 2007;99:5816

In a study of 60 obese patients undergoing bariatric

surgery, the ramped position improved laryngeal viewwhen compared to a standard sniff position. Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM. Laryngoscopy and morbid

obesity: a comparison of the "sniff' and "ramped" positions. Obes Surg 2004;14:15


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Head up vs supine sniff position Optimal positioning during face-mask ventilation and intubation is

vital. A study conducted by Collins et al demonstrated that placingmorbidly obese patients (BMI of more than 40) in a ramped position

gives a better laryngeal view than the standard sniff position.

Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM. Laryngoscopy and

morbid obesity: a comparison of the sniff and ramped position. Obes Surg.

2004;14:11715.

The ramped position is achieved by elevating the upper body and

head with the sternum and ear aligned in a horizontal line.

Similarly, elevating the head to 25 was shown to improve

oxygenation by 25%, as compared with supine positioning, in obese

patients (BMI of more than 40).

Dixon BJ, Dixon JB, Carden JR, et al. Preoxygenation is more effective in the 25

degrees head-up position than in the supine position in severely obese patients.

Anesthesiology. 2005;102:1110-5.


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Head-Elevated

Laryngoscopy Position"

(HELP)


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Head up position in Obese pt

Due to the change in lung and chest wallcompliance, obese patients tend to desaturatequickly and may be better served if they are placedin the head-elevated position.

In obese patients, administration of oxygen in the25-degree head-up position allows a greater safetymargin for induction of anesthesia than the supine

position by achieving 23% higher ox

ygen tensions.Dixon BJ, Dixon JB, Carden JR, Burn AJ, Schachter LM, Playfair JM, Laurie

CP, O'Brien PE. Preoxygenation is more effective in the 25 degrees head-upposition than in the supine position in severely obese patients: a randomizedcontrolled study. Anesthesiology 2005;102:11105


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Head up position in Obese pt

the routine practice during patient positioning before inductionis to use folded blankets, stacked under the patient's upperbody, neck, and head to elevate the head.

However, the number of blankets used differs among patients,and obtaining the optimum position in each patient is tedious,as it requires adding or removing blankets while repositioningthe patient each time (trial and error method).

Use of other devices

including a commercially

available foam pillow(Troop Elevation Pillow,

Mercury Medical,

Clearwater, FL)

to achieve this position


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Blanket method

folded blankets arestacked under thepatient's upper body,neck, and head toelevate the head.

to achieve a head-elevated position, the

patient's externalauditory meatus and

sternal notch were inthe same horizontalplane.


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OR table-ramp method


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This head-up position also can be achieved by a simple

maneuver of configuring the operating room (OR) table,similar to a reclining chair with the back or trunk portion of

the table up. With the patient lying on the OR table, the

electronic table controls can be used to flex the table at the

trunk-thigh hinge and raise the "back" or "trunk" section of

the table up as necessary to achieve the optimum position.

This can be done with or without the head-piece at the head

end of the table.


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Whelen-Collicott position

in this modified position,a roll or pad can beplaced under the head to

achieve neck flexion, butthe head of the bed iselevated (reverseTrendelenburg position)to achieve optimal

positioning withouthaving to placeadditional pads underthe patient's shoulders.


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OBJECTIVE

This prospective, randomized study was

designed to determine if the table-ramp

method of patient positioning wasequivalent to the blanket method with

regard to the time required for tracheal

intubation.


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METHODS

conducted in the OR of a university teaching hospital with ananesthesia residency program.

Written informed consent was obtained from 85 patientsbetween March 2007 and August 2007.

All 85 patients were

- ASA class I or II,

- age 2165 yr,

- undergoing elective surgeryunder general anesthesia.

- 64 underwent bariatric surgery (openor

laparoscopic gastric bypass, or gastric banding),

the remainder 21 underwent orthopedic, urologic,

or gynecologic surgery.


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PILOT STUDY

pilot study of 11 subjects undergoing

bariatric surgery using the current method

of patient positioning using blankets.

Pilot study were used to obtain an

estimate of the variability in the time

required to secure the airway for use in

power and sample size estimation for this

study.


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METHODS

only patients with a BMI >30 kg/m2 were approached tobe enrolled in the study

Patients with a history of difficult intubation were notenrolled.

Data collections:

obstructive sleep apnea

Age and gender

visibility of oropharyngeal structures was assessedusing the Mallampati Classification Method

Neck circumference (cm) at the level of the thyroidcartilage,

width of mouth opening (inter-incisor distance) (cm),

thyromental distance (cm)


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METHODS

2 mg of midazolam was administered IV to all

patients before transport to the OR.

Patients were then randomized using permuted

blocks randomization scheme of size 6 (known only

to the biostatistician during the study)

with subjects equally allocated to be positioned using

either the

1) blanket method or

2) OR table-ramp method.

The trial was designed to be stopped if there were

more than eight intubation failures (defined as more

than three attempts at laryngoscopy and intubation)

in the 85 study patients


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Blanket method

In the OR, patients in the blanket group lay on aramp made by layering multiple folded blankets on a

flat OR table.

Blankets were then added or removed to ensure that

the patient's head was above the shoulders and the

external auditory meatus and sternal notch were in

the same horizontal plane


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Patients in the table-ramp group were placed on the flatOR table with a hospital pillow under their heads toelevate their occiput, and the OR table was thenreconfigured to the position of a reclining chair.

With the patient lying on the OR table, the electronic

table controls were used to flex the table at the trunk-thigh hinge and raise the "back" or "trunk" section of thetable up as necessary to achieve the optimum positionofaligning the external auditory meatus to the sternalnotch.

This was done with the head-piece at the head end ofthe table in tall patients and without the head-piece inother patients.

The foot portion of the table was lowered by flexing theleg-thigh hinge so that the knees were slightly flexed to

avoid stretching the sciatic nerve


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OR table-ramp method the head piece of the table can be

moved independently to elevate thepatient's head if necessary to improve

glottic visualization

During bariatricsurgery, the patients

were positioned on the OR table atinduction in such a manner that they

could be placed in low lithotomy

position during surgery without moving

them.

if further flexion was required, one would have had to actively elevate the

patient's head manually.

This maneuver was not required in any of the study patients.


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METHODS

All pts were positioned by the same anesthesiologist. Using routine monitoring, anesthesia was induced using

100 g of fentanyl IV and

22.5 mg/kg (ideal body weight) propofol IV to achievehypnosis (loss of eyelash reflex).

Muscle relaxation was achieved with

1.01.5 mg/kg of succinylcholine or

0.61.0 mg/kg of rocuronium (lean body mass). Thechoice of muscle relaxant was at the discretion of theattending anesthesiologist in the room.

Manual bag-mask ventilation was attempted beforelaryngoscopy. An oral airway was inserted if the airwaywas obstructed.


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METHODS After loss of visible twitches using the single1 Hz stimulation at

the ulnar nerve, laryngoscopy was performed using a Macintosh

blade size 3.

The first laryngoscopy and attempt at tracheal intubation were

performed by the anesthesia resident or certified registerednurse anesthetist (CRNA) caring for the patient that day.

Second and subsequent laryngoscopies using a Macintosh 4 or

Miller 2 blade were performed by the attending anesthesiologist

taking care of the patient.

Each patient's trachea was intubated under direct vision using

an endotracheal tube (8.0 mm ID for men; 7.5 mm ID for

women).


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METHODS

The best view obtained during laryngoscopy was graded by the

Lehane-Cormack classification

The number of attempts at laryngoscopyand tracheal intubation were

noted separately.

The time intervalbetween the loss of consciousness (loss of eyelash

reflex) anddetection of CO2 on the end-tidal CO2 monitor after the

successful placement of the tracheal tube was noted as the time to

secure the airway.

Although the anesthesia resident or CRNA and the attending

anesthesiologist administering the anesthetic could not be blinded to

the method used to position the patient, theywere not aware of the

data points with regard to the outcome variables.


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after three failed attempts at laryngoscopy and

intubation, the patient would be managed at the

discretion of the attending anesthesiologist using the

anesthesia department's difficult airway practice

guidelines.

A "call for help" would be generated and the

attending anesthesiologist would be free to choose

the next modality or airway device at their discretion.


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Statistical Analysis

Equivalence trial: the time to tracheal intubation in obesepatients would be equivalent between the blanket and table-ramp groups

Pilot study: mean time and estimate of variability in the time tosecure the airway was obtained (mean time = 160 s, sd = 81 s)for use in power and sample size estimation for this study.

Equivalence bounds for time to intubation was defined as


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RESULTS

No difference in demographics between the groups.


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RESULTS


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RESULTS

The mean intubation time was175 (66) s in the blanket groupand

163 (71) s in the table-ramp group.

40 of 43 in the blanket group(93.0%)and

39 of 42 (92.8%) patients in thetable-ramp group underwentsuccessful tracheal intubation on thefirst attempt.

the 95% confidence interval forobserved difference in this studyfalls within the range of equivalence,therefore, the two methods areequivalent.


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RESULTS

There was no difference in the number of

attempts at laryngoscopy (P= 0.21) and

tracheal intubation (P

= 0.76) required tosecure the airway between the two

groups.


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DISCUSSIONS

the optimal position should be achieved beforeintubation, regardless of the means to achieve this

position.

It may indeed be easier, for both the patient and theanesthesiologist, to achieve the ideal position by

maneuvering the OR table, rather than inserting

wedges and blankets under the patient's torso.

The head-elevated laryngoscopic position could be

useful in delaying arterial desaturation as it would

allow better conditions for both spontaneous and

mask ventilation in an obese patient.


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DISCUSSIONS

The same head-elevated position can be used aftersurgery while weaning the patient off the ventilatorduring the extubation process. This is done moreeasily using the electronic controls of the OR table torecreate a table ramp during emergence instead of

reinserting blankets under the patient.

injury to OR personnel may occur when an attempt ismade to lift or move patients so that the blankets canbe removed from under the patients after tracheal

intubation.

Use of the electronic controls of the OR table toposition patients avoids these problems.


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DISCUSSIONS

As the proportion of obese patients has been

steadily increasing, the method of positioning

such patients becomes increasingly

important.

in obese patients, the head-elevated position

achieved by the simple maneuver of

elevating the back section of the OR tableshould be used, providing a greater margin

for safety, especially with trainees.


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DISCUSSIONS

Methods to secure airway in Obese patients:

Awake fibreoptic intubation

Various Laryngeal mask airways (LMAs)

LMA-fastrach LMA Ctrach

Glidescope

AirtraqTM laryngoscope etc


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DISCUSSIONS

The elevation pillow

used to achieve Head-Elevated LaryngoscopyPosition (HELP)


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HELP - Elevation pillow

Morbidly obese patient inrecumbent position withstandard intubation pillow only.This position creates

misalignment of the laryngeal,pharyngeal, and oral axis of theairway in the morbidly obese andlarge framed patients.

Morbidly obese patient properlypositioned for laryngoscopy usingstandard intubation pillow inconjunction with elevation pillow.Elevation of the shoulders and

upper back facilitates alignment ofthe laryngeal, pharyngeal and oralaxis of the airway in morbidlyobese and large framed patients.


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LMA-FASTRACH/ WHISTLE TECHNIQUE

The intubating laryngeal

mask airway (ILMA) is alsoknown as the LMA-Fastrach

The ILMA is inserted orally

to a depth where it restsupon the supraglotticlaryngeal structures of theupper airway.

A seal is produced whenthe mask is inflated,allowing the patient toeither breathespontaneously or beventilated manually via the

ILMA tube.


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LMA-FASTRACH TECHNIQUE


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LMA CTrach

LMA CTrachTM (CT), a modified version ofthe intubating LMA FastrachTM, allowscontinuous video-endoscopy of thetracheal intubation procedure.

British Journal of Anaesthesia 200697(5):742-745

Tracheal intubation of morbidlyobese patients: LMA CTrachTM vsdirect laryngoscopy

This study demonstrated that CT wasan efficient airway device for ventilationand tracheal intubation in case of adifficult airway in morbidly obesepatients.


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AirtraqTM laryngoscopes

British Journal of Anaesthesia 2008 100(2):263-268

Tracheal intubation of morbidly obese patients: a randomizedtrial comparing performance of Macintosh and AirtraqTM

laryngoscopes S. K. Ndoko*, R. Amathieu, L. Tual, C. Polliand, W. Kamoun, L. El Housseini, G. Champault and G. Dhonneur

Anaesthesia and Intensive Care Department and Visceral and Obesity Surgery Department,

Jean Verdier Public University Hospital of Paris (APHP), 93143 Bondy, France.

Paris 13 School of Medicine, 93000 Bobigny, France

the AirtraqTM laryngoscope shortened the duration oftracheal intubation and prevented reductions in arterialoxygen saturation in morbidly obese patients.


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AirtraqTM laryngoscopes

In this study, the AirtraqTM laryngoscope shortened the durationof tracheal

intubationand prevented reductions in arterialoxygen saturation in morbidly

obesepatients.

An operator intubating a manikinwith the AirtraqTM.

The operator slides the

endotracheal tube along the

channel along the AirtraqTM.

The tube is then removed fromthe Airtraq from the side

opening channel.


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Videolaryngoscope


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DISCUSSIONS

Equivalence Trials


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DISCUSSIONS

Equivalence Trials: Introduction The aim of an equivalence trial is to show the therapeutic

equivalence of two treatments

Problems:

Often include too few patients

Have intrinsic design biases which tend towards theconclusion of no difference

The application of hypothesis testing in analysing andinterpreting data from such trials sometimes lead toinappropiate conclusions

Inclusion and exclusion of patients from analysis may be

poorly managed


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DISCUSSIONS

Equivalence Trials:

failure to detect a difference does not imply equivalence.

A confidence interval defines a range for the possible truedifference between treatments, any point of which is compatible

with the observed data.

If every point within this range corresponds to a difference of no

clinical importance then the treatments may be considered tobe equivalent.


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DISCUSSIONS

Equivalence Trials:

a range of equivalence is predefined as the interval from -to +.

If the confidence interval centered on the observed difference lies entirely

between and +, equivalence is demonstrated.


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CONCLUSIONS

proper positioning before laryngoscopy and tracheal intubation

is important.

head-elevated laryngoscopic position(HELP) achieved by using

blankets under a patient's head and shoulders or by configuringthe OR table into a back-up position are equivalent with regard

to the quality of laryngeal exposure and time required to

achieve tracheal intubation.

This study propose that positioning patients in the head-elevated position by elevating the back or trunk section of the

OR table can be considered by clinicians as part of their

preformulated strategy in their daily clinical practice in

managing the airways of obese patients.


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THANK YOU


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1. Start with the patient on the back, in the middle of the bed and in goodalignment. The patient's hips should be at the place where the bend bends whenthe bed head is rolled up. Place the head of the bed at 30 for semi-Fowler's, 45to 60 for Fowler's, and 90 for high Fowler's.

2. Place one or two pillows behind the patient's head to extend four to fiveinches below the patient's shoulders.

3. Flex elbows and place a pillow under each arm to prevent pull on theshoulders.

4. Place a pillow under each leg to extend from above the knee and to the ankle,to prevent pressure on heels.

5 Place footboard or folded pillow to keep feet in position if necessary

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