Static Lung Volume Guideline - Queensland Health · PDF fileNote: Body plethysmography...

Version No.: 1.0; Effective From: 26 November 2012 of 37

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Document Number # QH-GDL-391:2013

Static Lung Volume

Measurement by body plethysmography, helium dilution, and nitrogen washout methods

Respiratory Science

1. Purpose

This guideline provides recommendations regarding best practice to support high quality measurement of static lung volumes and capacities using body plethysmography, helium (He) dilution and nitrogen (N2) washout methods throughout Queensland Health facilities.

2. Scope

This guideline provides information for all health practitioners who perform static lung volume testing in adult and paediatric patients over 7 years of age.

For more thorough evaluation of lung function, spirometry should be performed before static lung volume measurements.

3. Related documents

This guideline is primarily based on the following documents:

Miller, M. R., R. Crapo, et al. (2005). General considerations for lung function testing. European Respiratory Journal 26(1): 153-161. 1

Wanger, J., J. L. Clausen, et al. (2005). Standardisation of the measurement of lung volumes. European Respiratory Journal 26(3): 511-522. 2

References from alternate sources of information have been identified in this document.

Policy and Standard/s:

Informed Decision-making in Healthcare (QH-POL-346:2011) 3

Custodian/Review Officer:

Chief Allied Health Officer

Version no: 1.0

Applicable To:

All Health Practitioners performing adult and paediatric spirometry

Approval Date: DD/MM/YYYY

Effective Date: 26/11/2012

Next Review Date: 26/11/2013

Authority:

Chair – State-wide Clinical Measurements Network

Approving Officer

Chief Allied Health Officer

Supersedes: New Documentl

Key Words: spirometry, spiro, respiratory, measure, spirogram, spirometric, bronchodilator, flow-volume loop, peak flow, lung volume, SLV

Accreditation References:

EQuIP and other criteria and standards

http://www.health.qld.gov.au/qhpolicy/docs/pol/qh-pol-346.pdf

Queensland Health: Static Lung Volume

Version No.: 1.0; Effective from: 26 November 2012 of 37


Procedures, Guidelines, Protocols

Australian Guidelines for the prevention and control of infection in healthcare (CD33:2010) 4

2005 American Thoracic Society and European Respiratory Society (ATS/ERS) guidelines 1, 2, 5

Queensland Health Guideline: Spirometry (Adult) 6

Queensland Health Guideline: Spirometry (Paediatric)

Forms and templates

Nil

4. Guideline for performing static lung volume measurements

4.1. Emergency Protocol

Follow relevant Hospital and Health Service protocols or procedures in the event of an emergency.

4.2. Infection Control Procedures

Testing patients with confirmed or suspected communicable diseases may pose a risk to staff and other patients due to potential cross-infection. See Appendix 1 for detailed infection control procedures.

Adhere to relevant Hospital and Health Service infection control protocols or procedures at all times and in all facets of lung volume testing. Specific infection control procedures pertaining to lung volume testing are outlined in Appendix 1: Infection Control Procedures.

Australian Guidelines for the prevention and control of infection in healthcare (CD33:2010) 4

4.3. Gaining Consent

Gain consent in accordance with Queensland Health’s Informed Decision-making In Healthcare Policy 3.

4.4. Identifying Indications and Contraindications for performing static lung volume measurements

Indications for performing static lung volume measurements

Static lung volume measurements have a variety of uses including:

assisting with diagnostic evaluations 7

monitoring and assessment of pulmonary function 8

evaluating disability or impairment 8

http://www.nhmrc.gov.au/node/30290





providing public health information.

For further indications refer to Appendix 2: Purposes for performing spirometry and static lung volume measurements.

Contraindications for performing static lung volume measurements

The following are contraindications for spirometry testing 9, which is performed prior to static lung volume measures:

Some conditions may pose a relative danger to a patient or affect the validity of spirometry performance and results. These include, but are not limited to the following:

unstable cardiovascular status, unstable angina, recent myocardial infarction (within one month), or pulmonary embolism

haemoptysis of unknown origin

recent pneumothorax

thoracic, abdominal, or cerebral aneurysms

recent thoracic, abdominal or eye surgery

acute disorders such as nausea or vomiting

severe respiratory distress

physical limitations

cognitive impairment, dementia.

In addition to the above contraindications, the below contraindications apply to static lung volume measures:

Body Plethysmography

With respect to total body plethysmography, such factors as claustrophobia, upper body paralysis, obtrusive casts, intravenouslines or any factor that can limit the patient’s access into the box.

Patients over 150kg should be tested with caution. Refer to manufacturer’s recommendations for maximum weight limit.

If the patient is unable to weight bear on their own and move from wheelchair to the body plethysmograph unaided, and when wheelchair accessible plethysmograph is not available. (In this situation enquire with the requesting physician if the test is necessary for the patients treatment, and offer helium dilution or nitrogen washout techniques as an alternative test)

Temporary interruption of supplemental oxygen and intravenous fluids.

Note: Body plethysmography measures the total compressible gas volume in the thorax, and its accuracy is not affected by the presence of poorly ventilated airspaces.

Note: Body plethysmograph can be repeated within a short period of time. There is no long recovery time between manoeuvres as required in the gas dilution method.




Nitrogen washout (absolute contraindication)

Patients currently receiving Bleomycin treatment 10

Note: The helium dilution and nitrogen washout methods underestimate absolute lung volumes in patients with airflow obstruction because some areas of lung are insufficiently ventilated. For example, in patients with emphysema, or with bullous disease the lung volumes with these techniques are usually underestimated.

4.5. Facilities and equipment

Testing Facilities

Ensure clearly defined rooms are available, particularly for patients with confirmed or suspected communicable diseases, and immuno-compromised patients. Specific infection control procedures are outlined in Appendix 1: Infection Control Procedures.

For paediatric patients, the testing environment should be child–friendly 11

Spirometer (incorporated into the static lung volume equipment)

Ensure the technical specifications for spirometers or pneumotachs for the measurement of lung volumes and forced inspiratory and expiratory volumes comply with the ATS/ERS guidelines 1, 2.

Ensure helium dilution flow is greater than 7 L.s-1; for nitrogen washout 0 - 6L.s-1.

General supplies:

Stadiometer, scales, tape measure

Validated 3L-volume calibration syringe

In-line bacterial/viral filter mouthpiece and nose clip

Plethysmograph

Plethysmograph (body box) with specifications that comply with the ATS/ERS guidelines 2.

NOTE: There are several types of plethysmographs. Refer to Appendix 3: General principles of static lung volume measurements for further information.

Nitrogen Washout

Nitrogen washout equipment and associated accessories with specifications that comply with the ATS/ERS guidelines 2.

Medical Grade 100% oxygen

Calibration gas cylinder (approx. 16% O2, 4% CO2).

Helium Dilution

Helium dilution equipment and associated accessories with specifications that comply with the ATS/ERS guidelines 2.

Medical Grade 100% oxygen




Helium cylinder with appropriate gas mixture and according to manufacturer’s manual.

4.6. Training requirements

All health professionals performing spirometry should as a minimum complete the Queensland Health Spirometry Training Program or another spirometry training to an equivalent standard 12.

4.7. Preparing for the test

4.7.1. Key measures and terminology

Static lung volume is the volume of gas within the lung and can be measured using body plethysmography, helium dilution and nitrogen washout techniques. These methods measure various capacities and volumes as shown in Figure 1: functional residual capacity (FRC), total lung capacity (TLC), vital capacity (VC, IVC or EVC), inspiratory capacity (IC), tidal volume (TV), residual volume (RV), expiratory reserve volume (ERV) and inspiratory reserve volume (IRV). The FRC and VC (IC plus ERV) are the key components in the measurement of static lung volumes from which RV and the TLC can be derived.

Figure1. Spirogram showing the main lung volumes and capacities that are measured or derived during the measurement of TLC taken from Wagner (2005). 2

For more detailed principles underpinning the three techniques see Appendix 3: General principles of static lung volume measurements and Section 5: Definitions of terms.

4.7.2. Preparing equipment and ensuring quality control

See Appendix 4: Quality Control Procedures.

Refer to relevant manufacturer’s operations manual for equipment calibration, preparation and quality control guidelines.

For pneumotach calibration, refer to Appendix 4: Quality control procedures.




Ensure adequate warm-up period of at least 30 min.

Perform daily calibration according to manufacturer’s instructions.

Attach new in-line viral/bacterial filter mouthpiece for each patient.

Adjust the dead space volume, according to manufacturer’s instructions; particularly if other than regular mouthpieces are used.

4.7.3. Preparing the patient

Ensure all infection control measures are carried out prior to testing, particularly hand washing for both patients and personnel performing static lung function testing. See Appendix 1 for further infection control details.

The patient’s details such as name, hospital identification number, date of birth, gender, weight, height, ethnic origin and indications for the test will already be recorded on the system as it is recommended that spirometry is performed prior to performing static lung volumes.

Patient preparation regarding medications is as per the Queensland Health Guideline: Spirometry (Adult and Paediatric documents); as spirometry is performed prior to lung volume measurements.

Tight clothing, braces or vests may restrict full chest expansion and should be loosened or removed 1.

Interruption of supplemental O2 is necessary during measurements of body plethysmography and nitrogen washout. If it is safe to do so, supplemental O2 should be discontinued for at least 10 minutes before beginning the N2 washout test. In such patients, prior to performing the test and whilst disconnected from the supplemental oxygen, continuous monitoring of oxygen saturation should be performed. If this cannot be done safely, the interval of time off O2 must be recorded, and the results interpreted with caution.

The patient should be clearly instructed in the procedure prior to the commencement of the test and also be provided with ample opportunity to ask questions or receive clarification regarding the test and its requirements.

Dentures should be left in place unless they interfere with the testing procedure or the patient’s ability to perform the procedure as required 2.

Instruct the patient to place the nose clip on the nose, and mouth over the mouthpiece ensuring a tight seal is maintained during testing. A flanged rubber mouthpiece can be used if the patient is unable to maintain a tight seal.

4.8. Plethysmography 2

The patient should be seated comfortably in the plethysmograph with legs uncrossed and feet flat on the ground. Adjust the seat height or the level of the mouthpiece so that the patient does not need to flex or extend the neck.

Inform the patient that the plethysmograph door will be closed during the test and they will be able to hear test instructions through the intercom. They should also be shown how to open the door of the box from the inside.




Explain the procedure in detail and demonstrate the panting technique emphasising the frequency of the panting, between 0.5 - 1 Hz (1-2 pants per second). Advise the patient that the cheeks need to be supported by both hands and the nose clip must be in place during the manoeuvre.

Close the plethysmograph door and ensure that the microphone is functional.

Activate the software program according to the manufacturer’s instructions and allow the instrument an appropriate period for the thermal transients to stabilise and the patient to relax.

Adjust the volume scale if necessary to accommodate larger or smaller TLC measurements.

Instruct the patient to place the nose clip on, their mouth over the mouthpiece, ensuring a tight seal, and to commence normal tidal breathing until there is a stable end-tidal expiratory volume displayed (usually 3-10 breaths).

When the patient is at or near FRC, the shutter is closed at end-tidal expiratory volume-expiration for 2-3 seconds during which time the patient is instructed to gently pant at a frequency of 0.5-1 Hz (1-2 pant per second), supporting their cheeks with both hands (to minimise puffing of cheeks).

Advise the patient to continue panting against the shutter.

Record 3-5 technically satisfactory panting manoeuvres. These are displayed as a series of almost superimposed straight lines on the pressure-volume plot.

The FRCpleth measurement is the volume of intrathoracic gas measured when airflow occlusion occurs at FRC. Dependent on the system software a correction can be made for a switch in/switch out error (i.e. shutter not closed at FRC). Refer to manufacturer’s instructions.

Option 1

When the shutter is opened instruct the patient to expire fully to RV, then steadily inspire to TLC, before returning to normal tidal breathing. This is the FRCpleth – ERV – IVC linked manoeuvre (i.e. the patient stays on the mouthpiece for the entire manoeuvre).

If necessary the patient can rest between linked FRCpleth – ERV – IVC manoeuvres.

Option 2

When the shutter is opened instruct the patient to breathe normally to ensure the baseline end-tidal expiratory volume has not changed (normally due to a leak at the mouthpiece during panting). When satisfied the baseline end-tidal expiratory volume is unchanged, instruct the patient to inspire fully to TLC then steadily expire to RV. This is the FRCpleth – IC – VC linked manoeuvre (i.e. the patient stays on the mouth piece for the entire manoeuvre).

If necessary the patient can rest between linked FRCpleth – IC – VC manoeuvres.

Option 3

Note: Only use option 3 if options 1 and 2 cannot be performed by the patient




Perform FRCpleth only. This can then be coupled with separately measured IC/ERV-VC linked manoeuvres, which may be performed with the plethysmograph door open.

Perform at least three repeatable panting manoeuvres and three acceptable VC manoeuvres the two largest of which are within 0.15L (see acceptability and repeatability criteria below and the Queensland Health Guidelines: Spirometry (Adult and Paediatric).

Note: For individuals who cannot pant, follow the paediatric instructions outlined below for an alternative manoeuvre.

Note: During rest periods, the door may be opened, if necessary. Ensure appropriate equilibration time elapses before resuming the test. Consult equipment manufacturer’s instructions.

4.8.1. Paediatric test procedure 2

Children able to perform spirometry will be capable of performing the FRCpleth test. Older children are usually able to perform methods 1 and 2 above. In young children who cannot perform the panting manoeuvre an alternative is to perform a rapid IC manoeuvre against a closed shutter which is described below. In this case the TGV must be calculated using the complete TGV computation equation. For a detailed explanation see Appendix 5: Complete TGV computation equation.

A parent/carer may accompany the child in the plethysmograph, and if this is the case, the mass of the accompanying person must be accounted for 13.

The patient should be seated comfortably in the plethysmograph and without the need to flex or extend the neck when on the mouthpiece.

The patient should be informed the door will be closed during the test and there is an intercom so they will be able to hear test instructions. Also show how easily the box can be opened.

If there is an accompanying person, instruct them to cease breathing during the shutter occlusion 13.

Explain the manoeuvre which is a rapid inspiration against the closed shutter.

Close the plethysmograph door and ensure that the microphone is functional.

Activate the software program according to the manufacturer’s instructions and allow the instrument an appropriate period for the thermal transients to stabilise and patient to relax.

Volume scale can be adjusted if necessary to accommodate larger or smaller TLC measurements/volumes.

Instruct the patient to place the nose clip on nose, mouth over the mouthpiece, ensuring a tight seal, and to commence normal tidal breathing until there is a stable end- expiratory volume displayed (usually 3-10 breaths).

When the patient is at or near FRC, the shutter is transiently closed at end-expiration for 0.5-1 second during which time the patient is instructed to rapidly inspire. The




duration of the attempted inspiration must be less than 0.8 sec to avoid problems due to thermal drift 14.

Encourage the child to keep the mouth over the mouthpiece.

When the shutter releases, instruct the child to inspire fully, followed by an expired vital capacity.

Remove the mouthpiece and rest briefly before a repeated attempt.

4.8.2. Analysing the plethysmography results

The graphic results for each manoeuvre should be reviewed using the appropriate tools in the software. Adjustments can be made manually if necessary to alter the TLC, FRC and RV lung subdivisions. The FRCpleth slopes can also be manually altered to achieve the line of best fit if the software default measurements are incorrect.

4.8.3. Determining acceptability and repeatability of the results

Vital Capacity (VC)

See Appendix 6: Determining acceptability and repeatability criteria for spirometry.

FRCpleth

Within manoeuvre criteria

Individual panting manoeuvres are deemed acceptable if:

The panting manoeuvre shows a closed loop without drift or artefact. If thermal equilibrium has not been reached the loop tends to be open and to drift across the screen.

Stable end-tidal expiratory level is reached in 3-10 breaths

Shutter should be activated near FRCpleth (i.e end-tidal volume)

Panting frequency is approximately 0.5-1 Hz.

Pressure changes of ±10cmH2O (this should be within the range over which the transducers were calibrated i.e. the tracing does not go off the screen otherwise inaccuracies in measurements may occur)

Each pant should superimpose with little thermal drift.

Ideally a VC manoeuvre should be performed following each FRCpleth measurement, however this may prove difficult in some patients (see Option 3).

FRC measurements should be linked to technically satisfactory ERV/IVC or IC/VC manoeuvres.

Between manoeuvre criteria

At least 3 FRCpleth values that agree within 5% (difference between the highest and lowest value divided by the mean is ≤ 0.05) 2.

For the VC manoeuvre acceptability and repeatability criteria see Appendix 6: Determining acceptability and repeatability.




4.8.4. Reporting plethysmography results

All volumes are to be reported at BTPS conditions and in litres (L) to two decimal places.

The final report should include:

— Scientist’s comments regarding acceptability and repeatability of the data.

— Software version (if applicable).

— Date, time and results of most recent calibration.

— Identification of reference values used.

Option 1

Reported FRCpleth is the mean of at least 3 acceptable FRCpleth values in litres (L) to two decimal places.

Reported VC is taken from the largest acceptable and repeatable VC manoeuvres.

Reported RV is the reported FRCpleth minus mean of the acceptable ERVs that are linked to successful FRCpleth -ER-IVC trials.

Reported TLC is the reported RV plus the largest of the technically acceptable IVC.

Option 2

Reported FRCpleth is the mean of at least 3 acceptable FRCpleth values in litres (L) to two decimal places.

Reported VC is taken from the largest acceptable and repeatable VC manoeuvres.

The largest VC may also be quoted from a previous spirometry manoeuvre which has been performed during the same testing session

The TLC is reported as the mean of the 3 acceptable FRCpleth plus the largest linked IC.

Note: The best & second best IC should be within 150ml.

The RV is reported as the mean TLC minus the largest technically acceptable VC.

4.9. Multiple breath Nitrogen washout (adult and paediatric patients) 2

The patient should be asked if they have a perforated eardrum and, if so, an ear plug should be used. The patient should be assessed for current Bleomycin use as this is an absolute contraindication to performing the Nitrogen Washout procedure.

It is imperative that the Nitrogen (N2) Washout is performed after any CO diffusion measurements as breathing the 100% oxygen associated with this test can significantly reduce calculated DLCO and KCO.

The patient should be seated comfortably with feet flat on the ground and without the need to flex or extend the neck when on the mouthpiece.

Explain the procedure in detail emphasising the need to avoid leaks by maintaining a tight seal around the mouthpiece. If a flanged rubber mouthpiece is used the dead space volume will need be altered according to the manufacturer’s instructions.




Instruct the patient to place the mouth over the mouthpiece, ensuring a tight seal, and ensure that the patient has a nose clip in place during the entire procedure.

Activate the software program according to manufacturer’s instructions and instruct the patient to breathe normally until a stable baseline end-tidal expiratory volume is established.

When the end tidal volume is stable and at FRC, the patient is turned “into” the system so that 100% O2 is inspired rather than room air.

Instruct the patient to perform an IC-VC manoeuvre. This can be performed before or while breathing the 100% oxygen. Consult manufacturer’s instruction for further guidance.

Monitor the N2 concentration. This may be displayed as a function of FRC volume, as well as total washout volume or number of breaths. Consult manufacturer’s instruction for further guidance.

A change in inspired N2 of >1% or a sudden large increase in expired N2 concentration indicates a leak. In this case, the test should be terminated and the problem should be rectified.

Display the patient’s tidal volume and end-tidal CO2% in real time.

Instruct the patient to continue normal tidal breathing and to keep the mouth seal tight.

Continue testing until the N2 concentration falls below 1.5% for at least three successive tidal breaths. Gas mixing may be facilitated by asking the patient to take a large inhalation from the mouthpiece approximately every minute.

If the test continues for greater than 7 minutes and N2 stability (N2 < 1.5%) is not met, the test should be terminated. This condition indicates poor alveolar gas mixing and test results should be interpreted with caution.

Allow double the washout time before repeating the test. For example, if the test takes 4 minutes, then wait 8 minutes before repeating the nitrogen washout 15.

4.9.1. Determining acceptability and repeatability of Nitrogen washout results

VC

Repeatability of VC from 2 tests should be within 0.15L for adults and 0.1L for paediatric patients.

See Appendix 6: Determining acceptability and repeatability for spirometry.

FRCN2

At least 2 acceptable and repeatable manoeuvres must be performed.

No evidence of leaks in the system (a change in inspired N2 of >1% or a sudden large increase in expiratory N2 concentration)

N2 concentration is <1.5% for at least three successive tidal breaths before terminating the test.

Repeatability of TLC, FRCN2 and RV from 2 tests should be within 5% (no greater than 10%)




4.9.2. Reporting Nitrogen washout results







Reported FRCN2 should be the mean of technically acceptable results that agree within 10%.

Reported RV is the reported FRCN2 minus the mean of the technically acceptable ERVs that are linked to technically acceptable FRCN2 determinations.

Reported value for TLC should be the reported value for RV plus the largest of the technically acceptable IVC.

If only one acceptable measurement of FRCN2 is made then caution should be used in the interpretation and a note as such should be made in the report.

4.10. Multiple breath Helium dilution

The patient should be asked if they have a perforated eardrum and, if so, an ear plug should be used.

The patient should be seated comfortably with legs uncrossed and feet flat on the ground and without the need to flex or extend the neck when on the mouthpiece.

Explain the procedure in detail emphasising the need to avoid leaks by maintaining a tight seal around the mouthpiece. If a flanged rubber mouthpiece is used the dead space volume will need be altered according to the manufacturer’s instructions.

Instruct the patient to place the mouth over the mouthpiece, ensuring a tight seal, and ensure that the patient has a nose clip in place during the entire procedure.

Activate the software program according to the manufacturer’s instructions and instruct the patient to breathe normally until a stable baseline end-tidal expiratory volume is established.

When the end-tidal expiratory volume is stable and at FRC the patient is turned “into” the system (i.e. connected to the test gas) and should be instructed to continue breathing regular tidal breaths.

Continual adjustment of O2 flow should be made to compensate for O2 consumption otherwise significant errors in the FRC calculation can result. Helium concentration should be regularly monitored.

Instruct the patient to continue normal tidal breathing whilst maintaining a tight seal around the mouthpiece.




Continue testing until the change in helium concentration is <0.02% in 30s. The test is usually complete within 10 min even in severely obstructed patients. (Normal non- obstructed persons will take about 3-4 min to equilibrate.)

The patient should be turned “out” of the system (disconnected from the test gas).

Instruct the patient to exhale slowly and maximally to RV followed by a maximal inspiratory effort to TLC and then a return to normal tidal breathing. This is the linked FRCHe -ERV-IC manoeuvre.

At least one technically satisfactory measurement should be obtained. However, if more than one measurement is made it must be performed at least 5-10min after the patients has been breathing room air depending on the degree of airways obstruction 16.

4.10.1. Paediatric test procedure

For younger children it is recommended that at least two technically satisfactory measurements are performed 2.

4.10.2. Determining acceptability and repeatability of Helium dilution

Vital Capacity (VC)

See Appendix 6: Determining acceptability and repeatability for spirometry.

FRCHe

If more than one measurement is made FRCHe values should be the mean of technically acceptable results that agree within 10% of each other 2.

Helium concentration should be stable before testing. If falling baseline is noted check for leaks e.g. loose seal on the mouthpiece, a hole in the bag or circuit, nose clip not secure.

Rebreathing pattern should be even. Successive breaths will show a gradually falling end-tidal expiratory level as oxygen is consumed. Addition of oxygen should return breathing to close to the baseline.

If tidal breathing is irregular, ERV may be overestimated or underestimated, giving a lower or higher RV.

A VC manoeuvre along with its subdivisions ERV and VC should be performed during the same testing session.

Adequate time (between 5-10min) should be allowed between tests for complete washout of helium from the patient’s lungs.

FRCHe values should be consistent with spirometry results, and if not, may have resulted from leaks or inaccuracy or malfunction of the gas analyser.

4.10.3. Reporting results of Helium dilution










— Reported FRCHe should be the mean of technically acceptable results that agree within 10%.

— Reported RV is the reported FRCHe minus the mean of the technically acceptable ERVs that are linked to technically acceptable FRCHe determinations.

— Reported value for TLC should be the reported value for RV plus the largest of the technically acceptable IVCs.

— If only one acceptable measurement of FRCHe is made then caution should be used in the interpretation and a note as such should be made in the report.

4.11. Quality Control Procedures

Quality control procedures specific to spirometry testing are detailed in Appendix 4: Quality Control Procedures. Daily validation (calibration checks), weekly biological control testing, and data analysis are the minimum quality control requirements.

The following is performed in addition to the Quality Control procedures outlined in the Queensland Health Guidelines: Spirometry 6, 11

If a gas transfer has been performed prior to static lung volumes, check that the Alveolar Volume (VA) is smaller than the TLC. If an irregularity is found make sure all other parameters fit the clinical picture e.g. the VA could be significantly less than the TLC due to obstructive airways disease.

Check that the VC obtained during body plethysmography is the same or within 0.15L of the VC obtained during spirometry testing.

For N2 washout appropriate corrections for tissue and body fluid elimination of N2 should be made (see Appendix 3: General Principles of static lung volume measurements)

For He dilution ensure patients are at FRC when they are connected to the test gas. If not at FRC then a correction must be made before reporting results 2. Consult the manufacturer’s instruction.

4.11.1. Calibration

Perform calibration for each technique according to equipment manufacturer’s instructions.

For all methods:

3 L syringe for volume verification of spirometer performed at least daily 6.

Periodic servicing of equipment by the manufacturer is recommended.




For body plethysmograhy:

Mouth and box pressure transducers should be calibrated daily.

Plethysmograph signal should be calibrated daily using a volume signal of similar magnitude and frequency as the respiratory movements during testing.

Regular check of the plethysmograph leak time constant is recommended. See manufacturer’s instructions for frequency of check.

A validation of accuracy of the plethysmograph using an automated Isothermal Lung Simulator. See manufacturer’s instructions for use and frequency. Alternate methods for validation are described elsewhere 2.

For nitrogen washout:

2 point (0 & 4% CO2; 16 & 100% O2) calibration of gas analysers should be performed at least daily. Check manufacturer’s recommendations.

Calibration check should be performed before each patient by setting the N2 analyser to zero using 100% 02 and then exposing the analyser to room air which should be within 0.5% of the expected reading for room air (i.e.78.08%)

For helium dilution:

2 point (0 and full scale) calibration of gas analysers performed daily.

Before each patient the status of the CO2 absorbers should be checked.

Weekly checks of helium meter stability (drift should not exceed 0.02% in 10 min.)

Weekly checks of helium meter linearity. If stable over several months then checks only need to be performed quarterly or semi-annually.

Consult equipment manufacturer’s instruction manual for further calibration requirement.

4.11.2. Biological control characterisation and data analysis

Body Plethysmograhy

At least fortnightly, measure FRCpleth and related RV and TLC on at least two biological controls 2:

Calculate mean, standard deviation, and coefficient of variation for FRC, TLC, and RV.

FRC and TLC values that differ by >10%, and RV values that differ by >20% from previously established means for each subject suggest errors in measurements.

Refer to Appendix 4: Quality Control Procedures for analysis of the data and how to characterise the biological controls.

Nitrogen washout and helium dilution

Testing of at least two biological controls should be performed at least fortnightly.




5. Definition of Terms

Definitions of key terms are provided below.

Term Name Description

FRC Functional Residual Capacity (L)

The volume of gas present in the lung at end expiration during tidal breathing 2

ERV Expiratory Reserve Volume (L) The volume of gas that can be maximally exhaled from the end-tidal expiratory level during tidal breathing 2

IC Inspiratory Capacity (L) The maximum volume of gas that can be inspired from FRC 2

VC

IVC

EVC

Vital Capacity (L)

Inspiratory Vital Capacity (L)

Expiratory Vital Capacity (L)

The volume change at the mouth between the positions of full inspiration and complete expiration 2

IRV Inspiratory Reserve Volume (L) The maximum volume of gas that can be inhaled from the end-tidal inspiratory level during tidal breathing 2

RV Residual Volume (L) The volume of gas remaining in the lung after maximal exhalation 2

TV Tidal Volume (L) The volume of gas inhaled or exhaled during the respiratory cycle 2

TGV or VTG

Thoracic Gas Volume (L) The absolute volume of gas in the thorax at any point in time and any level of alveolar pressure 2

TLC Total Lung Capacity (L) Refers to the volume of gas in the lungs after maximal inspiration, or the sum of all volume compartments 2

VA Alveolar Volume (L) Total volume of gas available for exchange with blood under prevailing circumstances. Expressed as the lung volume less the volume of the conducting airways 17

DL,CO Diffusing capacity for carbon monoxide

Also known as transfer factor of the lung for CO; product of the KCO and VA 18

KCO Transfer coefficient of the lung Diffusing capacity for carbon monoxide per unit of alveolar volume i.e. DL,CO/VA 18




6. Consultation

Key stakeholders (position and business area) who reviewed this version are:

Queensland Health Respiratory Working Party: Michael Brown (Director of Respiratory & Sleep Sciences, Royal Brisbane and Women’s Hospital), Andrew Coates (Chief Respiratory Scientist, Mater Health Services), Annette Dent (Scientific Director, Respiratory Science, The Prince Charles Hospital), Janine Ferns (Respiratory/Sleep Scientist-Advanced, Cairns Base Hospital), Leanne Rodwell (Respiratory Scientist, Royal Children’s Hospital), Irene Schneider (Respiratory Sciences Clinical Educator, Respiratory Working Party Chair, The Prince Charles Hospital), Jessica Wilson (Respiratory Scientist, Respiratory Working Party Assistant Chair)

Clinical Measurements Advisory Group (CMAG) for Clinical Education and Training.

State-wide Clinical Measurements Network (SWCMN)

Queensland Health Respiratory Laboratory Managers: Chris Brown (Respiratory and Sleep Scientist – Advanced, The Townsville Hospital), Barry Dean (Respiratory Scientist, Royal Children’s Hospital), Brenton Eckert (Scientific Director, Princess Alexandra Hospital), Ryan Harle (Respiratory Scientist – Laboratory Manager, Logan Hospital), Andrew Southwell (Senior Clinical Measurement Scientist - Respiratory, Redcliffe/Caboolture), Joanne Wex (Manager- Clinical Measurements, Rockhampton Base Hospital), Debbie Zagami (Respiratory Scientist-Laboratory Manager, Gold Coast Hospital)

Queensland Health Respiratory Laboratory Clinical Directors: Scott Bell (Thoracic Program Medical Director, The Prince Charles Hospital), Anthony Matthiesson (Director Respiratory and Sleep Unit, The Townsville Hospital), Stephen Morrison (Director of Thoracic Medicine, Royal Brisbane and Women’s Hospital), Brent Masters (Director, Queensland Children’s Respiratory Centre), Graham Simpson (Director of Thoracic Medicine, Cairns Base Hospital), David Serisier (Director, Respiratory Medicine, Mater Health Service), Pathmanathan Sivakumaran (Director, Respiratory Services, Gold Coast Hospital), Khao Tran (Respiratory Physician, Logan Hospital), Dr Craig Hukins (Director, Department of Respiratory and Sleep Medicine, Princess Alexandra Hospital)

State-wide Respiratory Clinical Network (SWRCN), Deb C. Hill (Network Coordinator, State-wide Respiratory Clinical Network & Principal Project Officer, Clinical Networks Team, Patient Safety & Quality Improvement Service, Centre for Healthcare Improvement)

7. Guideline Revision and Approval History

Version No.

Modified by

Amendments authorised by

Approved by

1.0 Dane Enkera - Chair State-wide Clinical Measurements Network

Brett Duce - Chair Clinical Measurements Advisory Group (for clinical education)




8. Appendices

Appendix 1: Infection Control Procedures

The aim of infection control is to provide a better understanding of infections and their modes of transmission to staff. It is also important in maintaining a safe working environment for staff and patients to help prevent disease transmission during pulmonary function testing.

General Hygiene guidelines:

Poor hygiene practice not only increases patient morbidity but also increases patient mortality. Lung function testing equipment has the ability to spread or transmit blood borne and airborne pathogens (droplets and other particles containing microbes being released in the air) e.g. tuberculosis (TB), chicken pox respiratory syncytial virus (RSV), human immunodeficiency virus (HIV) and hepatitis. The majority of the patient population would not be affected but individuals who are immune-compromised are far more likely to develop complications 4.

If an active respiratory infection has been identified in a patient then the test request should be confirmed with the requesting medical officer.

Transmission of pathogens 1, 8:

Transmission of pathogens can occur via a number of different routes including: patient - staff, staff – patient, patient – patient, staff – staff, patient – equipment and staff – equipment.

ATS/ERS guidelines 1 define direct and indirect contact with regards to pulmonary function testing and transmission of pathogens as follows:

Direct contact: (From person to person)

There is the potential for transmission of upper respiratory disease, enteric infections, and blood-borne infections through direct contact. Although hepatitis and HIV transmission are unlikely via saliva, disease transmission is a possibility when there are open sores on the oral mucosa, bleeding gums, or haemoptysis. The most likely surfaces for contact are mouthpieces and the immediate proximal surfaces of valves or tubing.

Indirect contact: (Via animate and inanimate objects)

There is potential for transmission of TB, various viral infections, and possibly, opportunistic infections and nosocomial pneumonia through aerosol droplets. The most likely surfaces for possible contamination by this route are mouthpieces and proximal valves and tubing.




Prevention and Precautions:

Standard precautions should be followed at all times. Disease prevention or cross contamination can be prevented by addressing the following issues regarding the source and the transmission of pathogens:

ensuring a clean environment

proper hand-washing techniques

sterilisation and disinfection of equipment including valves and tubing

use of in-line bacterial/viral filters safety mouthpieces

personal protective equipment (e.g. gloves, gown, masks etc)

isolation of infected patients (Source Isolation)

precautions with testing patients with open sores or haemoptysis

isolation of susceptible patients (Protective Isolation).

Hands should be washed between patients and immediately after direct handling of mouthpieces, tubing, breathing valves or the interior surfaces of equipment. Gloves should be worn at all times when handling contaminated equipment or where surfaces are suspected of holding pathogens which could be potentially transmitted. Gloves also offer another barrier of defence for staff with open cuts or sores which need to be covered to prevent contamination and/ or transmission of disease pathogens.

Volume and flow-based spirometers:

Disposable in-line filters are an effective and less expensive method of preventing equipment contamination. In-line filters have been shown to remove microorganisms from the expiratory air stream and thus prevent their deposition as aerosol nuclei on spirometer surfaces. The use of in-line filters does not eliminate the need for regular cleaning and decontamination of lung function equipment. When using equipment with inspiratory and expiratory manoeuvres, in-line bacterial/ viral filters should be used and disposed of after every patient (single patient use).

Closed circuit

A volume based spirometer in which a closed circuit technique has been used should be flushed between subjects with room air at least five times over the entire volume range of the spirometer to enhance clearance of droplet nuclei. The breathing tube or mouthpiece should be decontaminated or changed between patients.

Open circuit

If the patient or subject only exhales into the spirometer, only the portion of the circuit through which re-breathing occurs must be decontaminated between patients. Alternatively a disposable sensor may be used and decontamination of sensors and mouthpieces can be avoided. A low resistance disposable one-way valve mouthpiece may




be used to prevent inhalation from an open circuit. This mouthpiece needs to be disposed of between patients.

Common transmissible infectious diseases often seen in the Respiratory Laboratory include:

Hepatitis B

Hepatitis C

Tuberculosis (TB)

Human Immunodeficiency Virus (HIV)

Pseudomonas cepacia

Cytomegalovirus (CMV)

Varicella Zoster Virus (VZV).

The ATS/ERS 1 recommends extra precautions are taken for patients with known transmissible infectious diseases.

Reserve equipment for the sole purpose of testing infected patients.

Test infected patients at the end of the day, allowing time for the equipment to be disassembled and disinfected.

Test patients in their own rooms with adequate ventilation and appropriate protection for the technician. A negative air conditioned room is ideal for this situation and aids in the prevention of cross contamination.

Place patients in a separate area apart from other patients, not in open waiting areas.

Provide patients with surgical masks and instruct them to wear the masks. Provide patients with tissues and instructions on covering their mouth and nose when coughing or sneezing.

Environmental engineering controls such as ventilation, air filtration or ultraviolet decontamination of air should be used to help prevent disease transmission where spread is by droplet nuclei as seen in tuberculosis.

Cleaning and Disinfecting Procedures

Mouthpieces, nose clips, and any other equipment coming into direct contact with mucosal surfaces should be disinfected, sterilized, or, if disposable, discarded after each use. Although the optimal frequency for disinfection or sterilization of tubing, valves, or manifolds has not been established, any equipment surface showing visible condensation from expired air should be disinfected or sterilised before reuse whenever the potential for cross contamination exists.

Manufacturer’s recommendations regarding the cleaning and disinfection of equipment must be consulted in order not to cause damage with the wrong cleaning procedure. Heat sterilisation or cold sterilisation chemicals can damage flow sensors, tubes and/ or seals.




Manufacturers should describe the recommended chemicals and concentrations as well as the PPE required by the staff undertaking the cleaning and disinfection procedure. However, Queensland Health infection control requirements supersede the manufacturer’s recommendations so long as the equipment will not be damaged by these procedures.

All materials must be cleaned of debris before undergoing the disinfection process. There are four main categories of sterilization and disinfection. ; These are described below 8.

Heat

Heat is the universally employed and most reliable form of sterilization and is listed below in order of efficiency:

Steam under pressure (autoclave)

Steam at atmospheric pressure

Boiling water

Dry heat under pressure

Dry heat at atmospheric pressure

Water below boiling point (pasteurization).

Cold liquid

Glutaraldehydes disinfect by interrupting metabolism and reproduction in microorganisms by binding to amino groups of proteins. These agents are bactericidal, tuberculocidal, fungicidal and viracidal in 10-30 minutes and sporicidal in 10hours. Many of these agents require special precautions. Comply with the material safety data of the product.

Gas

Ethylene oxide (ETO) is the alkylating agent used extensively in gas sterilisation. However this agent is unsafe for the environment and requires stringent material preparation and monitoring.

Other liquid disinfectants

Other disinfectant liquids include alcohol, quaternary ammonium compounds, acetic acid, formaldehyde, phenols, iodine, chlorine, and hydrogen peroxide.

1. Acetic acid solutions, quaternary ammonium compounds, and household bleach may be used for disinfecting respiratory equipment. However, studies have not been performed to verify the usefulness of these agents.

2. Alcohol and hydrogen peroxide may be used for skin cleaning and disinfection.




Appendix 2: Purposes for performing static lung volumes

Purposes for performing spirometry 9:

Diagnostic indications

evaluate symptoms, signs or abnormal laboratory tests – abnormal lab tests

measure the effect of disease on pulmonary function – pulmonary dysfunction

screen individuals at risk of having pulmonary disease – risk stratification

assess pre-operative risk – pre-operative assessment

assess prognosis – prognostic indicator

Monitoring indications

assess therapeutic intervention

describe the course of diseases that affect lung function

monitor people exposed to injurious agents

monitor for adverse reactions to drugs with known pulmonary toxicity

Disability/Impairment Evaluations

assess patients as part of a rehabilitation program

assess risks as part of an insurance evaluation

assess individuals for legal reasons

Public Health

epidemiological surveys

derivation of reference equations

clinical research

Purposes for performing static lung volume measurements (in addition to the above purposes for performing spirometry):

Diagnostic: 4

evaluate symptoms, signs or abnormal laboratory tests and confirm restrictive ventilatory defects

diagnose hyperinflation and gas trapping as may occur in patients with obstructive lung disease

diagnose, evaluate and monitor diseases which involve the lung parenchyma (eg. those associated with dusts, drug reactions, or sarcoidosis)

differentiate types of lung disease processes characterized by airflow limitation that have similar forced expiratory volumes




aid in the interpretation of other lung function tests (lung elastic recoil pressure, instantaneous ventilatory flows, gas transfer factor).

Monitoring and assessment: 5

assess response to therapeutic intervention (e.g., drugs, transplantation, radiation, chemotherapy, and lobectomy and lung volume reduction procedures/surgery)

make preoperative assessments when indicated

quantify the amount of non-ventilated lung

evaluate and monitor:

— pulmonary disability

— impairment and disability associated with interstitial lung diseases and chronic obstructive airway diseases

— pulmonary effects of radiation therapy, chemotherapy agents (eg Bleomycin) or other drugs known to induce pulmonary dysfunction

— pulmonary involvement in systemic diseases.

Public health:

epidemiological surveys

derivation of reference equations

clinical research.




Appendix 3: General Principles of static lung volume measurements

Body plethysmography

The measurements made using body plethysmography are based on Boyle’s Law, which states that, under isothermal conditions, if a given mass of gas is compressed or decompressed, the gas volume decreases or increases and the gas pressure changes so that the product of the gas volume (V) and gas pressure (P) is constant. This relationship is described by the following equation:

P1V1 = P2V2

During body plethysmography the thoracic volume can be obtained by measuring the changes in the following:

KP

P

V

PV

MouthCal

BoxCal

TG

B

TG

Where:

VTG = thoracic gas volume (V2) measured at FRC

PB = barometric pressure (P1)

VTG = slope of the displayed line equal to P/ V

PBox Cal = box pressure transducer calibration factor

PMouthCal = mouth pressure transducer calibration factor

K = correction factor for volume displaced by the subject

Types of body plethysmographs

1. Constant – volume plethysmograph (variable-pressure plethysmography)

2. Constant – pressure plethysmograph (variable-volume plethysmography)

3. Flow plethysmography

More detailed reviews of the theory are available 19.




Multiple-Breath Nitrogen Washout

The principle of the method is that N2 is washed out of the body by the patient after a period of breathing 100% oxygen. The first inspiration of 100% O2 is taken from FRC and the expired volume is collected over a 7 minute period. The N2 concentration in the expired gas gradually falls during the test and washout until it reaches a value of <1.5% . FRC is calculated using the following formula 17:

2212

22

alveolarAalveolarA

tissuefinalE

NFNF

NumeExpiredVolNFFRC

Where:

FEN2final = Fraction of N2 in volume expired

FAN2alveolar1 = Fraction of N2 in alveolar gas initially

FAN2alveolar2 = Fraction of N2 in alveolar gas at end

N2tissue = Volume of N2 washed out of blood/tissues

For each minute of O2 breathing, approximately 30 to 40 mL of N2 are removed from the blood and tissue. Therefore:

N2tissue = 0.04 x T (where T is time of the test).

The final FRC is then corrected to BTPS.

Determination of indices for reporting

TLC = Average of all FRC + Best IC

VC = The highest VC measured from spirometry or lung volume measurements

RV = Calculated TLC – Best VC

FRC = Average of all trials

IC = Largest IC of all trials (* best and second best must be within 10%)

VTG = Average of all trials

ERV = Average of all trials




Multiple-breath Helium Dilution

The subject breathes from a closed circuit a gas mixture containing 9.5% helium, 35% oxygen with a nitrogen balance. The gas mix equilibrates gradually with the resident gas in the lungs. The helium concentration falls progressively, stabilising once mixing is complete. In normal healthy individuals this is achieved in 5-10minutes, but in patients with airway disease mixing is much slower and the endpoint much less definite. During rebreathing, CO2 is absorbed by a Sodalime scrubber and oxygen is added continuously to maintain a constant overall volume of the system (equipment+lungs). The volume measured is that at which the subject is switched into the circuit, FRC + VD, where VD is the sum of the apparatus and anatomic dead spaces. The total amount of helium (He) equals the product of its concentration and the volume (V) in which it is distributed. The initial fractional concentration of He (F1He) in the circuit (V1) falls after switching, reaching an equilibrium concentration F2He. The total amount of helium is unchanged.

Calculation:

Therefore V1.F1He (amount of He) = V2.F2He (amount of He)

= (V1 + FRC + VD).F2He

FRC + VD =V1(F1He – F2He)

F2He

At the end of the procedure the subject takes a full inspiration from a spirometer and expires fully back into the spirometer. The inspiratory capacity recorded is added to FRC to give TLC and the VC is subtracted from the TLC to give the RV.

V2

VD

FRC

V1

F1 He F2 He




Appendix 4: Quality Control Procedures

Quality control must be conducted to ensure the precision and accuracy of the test equipment, test procedure and the results collected. It includes the regular maintenance and calibration of equipment and the regular testing of biological controls to validate testing equipment and test procedures. All results of quality control testing should be recorded and analysed so that any problems can be identified and rectified as soon as they arise. Quality control processes that conform to a “best practice model” are outlined below 8.

Instrument maintenance

Regular preventative maintenance must be performed by the operator to anticipate problems with the equipment before they occur. These should be done daily, weekly, monthly or yearly depending on the recommendation of the manufacturer.

checking volume-displacement spirometers for leaks and linearity

checking tubing for tears

electrical safety

Corrective measures include unscheduled action required to correct the instrument failure and can be performed by the manufacturer, hospital bioengineer or the operating staff.

Maintenance logs must be kept and include dates and types of tasks conducted along with instructions on what action is to be taken if a problem is identified and needs to be rectified. At a minimum the following record should be kept:

problem or troubleshooting log

preventative maintenance list/log

calibration log

quality control log

New Instrumentation verification and validation must be performed on all new equipment before patient testing begins.

Instrument Calibration

To have confidence in the data that is generated during spirometry testing, the spirometer must be regularly calibrated for volume, linearity and timing. Depending on the type of spirometer used, some or all of these parameters need regular validation.

Calibration syringe 5

The calibration syringe should be stored at the same temperature and humidity as the testing site, away from direct sunlight and heat sources. This is best achieved by storing the syringe close to the spirometer.

A calibration syringe should be used to check the volume calibration of spirometers and must have an accuracy of ±15mL or 0.5% of the full scale, whichever is greater. For most spirometers the syringe volume required is 3L.




A calibration syringe should be validated yearly to ensure accuracy. For specific details refer to the manufacturer’s recommendations.

A calibration syringe should be checked monthly for leaks by attempting to empty it with the outlet occluded. This should be performed at more than one volume.

Perform inspection of adjustable or variable stops, if they exist, especially if the syringe has been dropped or damaged.

Use of the syringe on a large number of machines distinguishes between instrument problems and problems with the syringe.

Procedure for validation (calibration checks)

Volume validation ensures that the spirometer is within calibration limits (+/-3% of the true volume, usually 3L where a 3L syringe is used).

Volume validation should be performed at least daily, or after every 10 patients in a busy service 20.

Recalibration may be indicated and BTPS correction factors updated if the temperature changes more than 50° C 1.

In-line bacterial/ viral respiratory filters must be in place during the validation if they are used during testing 12.

For volume-based spirometers 5

— Check spirometer for leaks daily by applying a constant positive pressure of ≥3.0cmH20 (0.3 kPa) with the spirometer outlet occluded at the mouthpiece, preferably with the mouthpiece in place. A volume loss of 30ml after 1min indicates a leak and needs addressing.

— Perform validation at least daily with a calibration syringe (the volume of the syringe will depend on the type of spirometer being used). Check manufacturer’s guidelines for details.

— A volume linearity check should be performed quarterly (1L increments with a calibrating syringe over entire volume range). The procedure is detailed in the ATS/ERS guidelines 9. The check is considered accurate if the minimum volume accuracy requirements are met for all volumes tested, i.e. measured volume should be within ±3.5% (this value includes the 0.5% syringe accuracy limit of the reading or 65ml, whichever is greater).

— The following method can be used to check the linearity for each volume tested:

— Perform timer checks quarterly for spirometers with mechanical recorder time scale. Using a stopwatch, an accuracy of 2% must be achieved.

% Error = Expected Volume – Measured Volume X 100

Expected Volume

Where: Expected volume = the actual volume of the syringe

Measured volume = the result recorded for the test




For flow-based spirometers 5:

— Perform validation at least daily with a 3L syringe. Check manufacturer’s guidelines for details.

— A 3.00 L syringe should be injected at three different flow rates between 2 and 12 L.s-1 (with 3L injection times of ~6sec and < 0.5 sec); minimum volume accuracy should be within 3.5% at all flows.

— For spirometers that use disposable flow sensors, a new unused sensor should be tested daily.

— A flow linearity check of pneumotachs weekly ensures that minimum volume accuracy is met for the entire range of flows measured (low-, mid-, high-flows). If the spirometer meets volume accuracy requirements of ±3.5 ml for all flow rates tested then it meets the requirements for linearity.

Quality Control Analysis

Data from calibrations and other quality control procedures must be analysed regularly in order to be useful and contribute to quality assurance procedures. The results analysed must be obtained in a stable laboratory environment using the same calibration syringe, calibration procedure, biological standard or control material (eg. 3L syringe).

Biological Control is a healthy, non-smoking individual, usually a staff member, that is regularly tested and becomes the reference standard for the quality control program.

Biological control characterisation

Biological controls must initially be “characterised” according to the “gold standard” testing procedures before the data becomes the “reference standard”. The biological control’s lung function must be measured as accurately as possible under ideal conditions to determine a baseline value. All subsequent testing of the biological control is compared to this baseline value. Characterisation determines the variability of the biological control under the most ideal conditions.

Characterisation requires that:

FEV1, VC, FVC volumes are measured according to ATS/ERS guidelines for acceptability and repeatability5.

The subject is free of symptoms or known respiratory disease that may cause variability in lung function results.

Data is collected at least 10 times over a 1-2 week period under the above conditions to assess variability of the individual’s data.

The mean for each measured parameter becomes the reference standard or the “correct value”.

Biological control data analysis

Day to day variations in physiological function of the biological control occur even under ideal testing conditions. The variability is used to set the “control limits for the test”, and allows identification of data that is “out of control”, and is determined by the following steps:




record FEV1, FVC, VC for the 10 or more test manoeuvres performed

for each parameter measured calculate mean and standard deviation (SD)

the mean value during gold standard testing is the “correct value” for the biological control

the standard deviation (SD) can now be used to set the control limits, where, mean ± 1.96 x SD gives a confidence interval of 95%, this means that approximately 95% of the values will be between ± 2SD of the mean.

The biological control results, collected on a regular basis, can be plotted on a Levy-Jennings plot (see Graph 1) and interpreted using the Westgard rules. Westgard rules can be used to define specific limits for biological control results when compared with the “gold standard” testing results and to help determine if quality assurance responses need to be enacted, as follows 8:

— When one control observation exceeds the mean ±2 SD, a "warning" condition exists

— When one control observation exceeds the mean ±3 SD, an "out of control" condition exists

— When two consecutive control observations exceed ±2 SD, an "out of control" condition exists

— When four consecutive control observations exceed the mean ±1 SD in the same direction, an "out of control" condition exists

— When 10 consecutive control observations fall on the same side of the mean, an "out of control" condition exists

— Generally, the following rules apply:

— the ±2 SD limits are considered warning limits

— values between 2 and 3 SD limits indicate an error and the procedure should be repeated

— values beyond ±3 SD are considered unacceptable and the testing system should be evaluated.

Biological control testing procedure

Routine biological control testing is performed weekly.

Routine biological control testing is performed under the same condition as routine patient testing according to ATS/ERS guidelines 5.

Graph the biological control result on a Levy-Jennings Plot (see Graph 1), which has horizontal lines running across it to indicate the mean, as well as one, two and sometimes three standard deviations either side of the mean (derived from the characterisation of the biological control). These provide visual feedback of whether control values are “in” or “out of control”.

Westgard rules are then used to determine if any quality assurance procedures need to be enacted.




Graph 1. Example of a Levy-Jennings plot showing the mean and one and two standard deviations derived from biological control characterisation. The observation points are VC results obtained from a biological control. In this example, no quality assurance procedures need to be enacted.

Levy -Jennings Plot (VC)

3.08

3.1

3.12

3.14

3.16

3.18

3.2

3.22

3.24

3.26

3.28

0 2 4 6 8 10 12

Observation number

VC

(L

) R

esu

lt




Appendix 5: Complete TVG computation equation.

For young children, where the rapid IC manoeuvre against a closed shutter is used to measure FRC, the plethysmograph should be set to “VTG on Inspiration only” mode. Not “VTG by occlusion”. It is essential that the complete rather than the simplified version of the VTG computation equation be used in the calculation of VTG.

i.e.

TGV=-(ΔV/ΔP)xPalv2x(Palv1/PB)

as opposed to

TGV=-(ΔV/ΔP)xPB.

Not using the complete formula will result in an error of about 5%. If a computerized system is used for such measurements, the user must confirm that the complete equation is used by the computer during such measurements 2, 14.




Appendix 6: Determining acceptability and repeatability of FEV1, FVC and VC measurements

Extract taken from Queensland Health Guideline: Spirometry (Adult) 6

Clinically useful spirograms must be acceptable (i.e meet the criteria that comprises a good quality manoeuvre) and repeatable (i.e the two highest FEV1, FVC and VC from three acceptable manoeuvres are in close agreement).

A spirogram is “acceptable” if the following are met:

Start of Test Criteria

begins from full inspiration

has a rapid start of test, that is, the back extrapolated volume (BEV) is <5% of FVC or 0.15L, whichever is greater (see Appendix 7: Determination of back-extrapolation volume). If the manoeuvre has an obviously hesitant start then the trial should be terminated early to avoid unnecessary prolonged effort.

Middle of Test Criteria

No obstruction, hesitation or artefact impeding the blow including:

a. Cough during the first second of exhalation

b. Glottic closure that influences the measurement

c. Early termination or cut-off

d. Effort that is not maximal throughout

e. Air leaks at mouth

f. Obstructed mouthpiece (due to tongue or teeth in front of the mouthpiece, or mouthpiece deformation due to biting).

Note: See below for examples of volume-time and flow-volume spirograms.

End of Test Criteria

Continuous maximal expiratory blow for ≥6 sec in duration

A plateau in the volume-time curve (i.e. no change in volume (<0.025L) for a 1 second period)

The patient cannot or should not continue to exhale 5.

How to ensure repeatability between individual spirograms

After three acceptable spirograms have been obtained, the following checks are used to assess for repeatability:

The two largest values of FVC or VC must be within 0.150L of each other

The two largest values of FEV1 must be within 0.150L of each other

For patients with an FVC or VC of ≤1.0L the two largest FVC or VC and FEV1 values must be within 0.100L of each other




A minimum of three acceptable manoeuvres should be saved and utilised for analysis/interpretation.

Peak expiratory flow (PEF)

During spirometry testing PEF is measured in conjunction with FEV1 and FVC and can be used to indicate maximal patient effort.

Note: PEF can also be measured independently using a Peak Flow Meter. Refer to ATS/ERS guidelines (2005) 5.

Examples of volume-time and flow-volume spirograms

Figure 1. Examples of unacceptable volume – time spirometry results compared with a good effort 21




Figure 2. Examples of unacceptable flow-volume spirometry loops compared with an acceptable effort 21

9. Suggested Readings and References

9.1. Suggested readings

Cooper BG. 2010. An update on contraindications for lung function testing. Available

from: http://www.ncbi.nlm.nih.gov/pubmed/20671309. 22

Johns DP and Pierce RP. 2007. Pocket Guide to Spirometry. 2nd edition, McGraw-Hill Australia. 21

Quanjer PH. Become an Expert in Spirometry: Lung function indices. Available from: http://www.spirxpert.com/indices7.htm 23_ENREF_16

Queensland Health Spirometry Training Program. Available from: https://ilearn.health.qld.gov.au/login/index.php 24

9.2. References

1. Miller MR, Crapo R, Hankinson J, Brusasco V, Burgos F, Casaburi R, et al. General considerations for lung function testing. Eur Respir J. 2005 Jul;26(1):153-61.

2. Wanger J, Clausen JL, Coates A, Pedersen OF, Brusasco V, Burgos F, et al. Standardisation of the measurement of lung volumes. Eur Respir J. [Review]. 2005 Sep;26(3):511-22.

3. Queensland Health. Informed decision making in health care2012: Available from: http://www.health.qld.gov.au/consent/default.asp.

4. National Health and Medical Research Council. Australian Guidelines for the Prevention and Control of Infection in Healthcare. National Health and Medical Research Council; 2010 [cited 2012 12/09/12]; CD33:[Available from: http://www.nhmrc.gov.au/node/30290.

http://www.ncbi.nlm.nih.gov/pubmed/20671309

http://www.spirxpert.com/indices7.htm

https://ilearn.health.qld.gov.au/login/index.php

http://www.health.qld.gov.au/consent/default.asp





5. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J. [Practice Guideline]. 2005 Aug;26(2):319-38.

6. Queensland Health. Queensland Health Guideline: Spirometry (Adult)2013: Available from: http://www.health.qld.gov.au/qhpolicy/docs/gdl/qh-gdl-386.pdf.

7. Quanjer PH, Tammeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernault JC. Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society. Eur Respir J Suppl. [Review]. 1993 Mar;16:5-40.

8. American Thoracic Society. Pulmonary Function Laboratory Management and Procedure Manual 2nd ed. Wanger J, Crapo R, Irvin C, editors: American Thoracic Society; 2005.

9. American Association for Respiratory Care. AARC Clinical Practice Guideline: Spirometry, 1996 Update. Respiratory Care. 1996;41(7):629-36.

10. Therapeutic Goods Administration. Bleomycin. Australian Government; 2013 [cited 2012 21/02/2012) ]; Available from: https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/PICMI?OpenForm&t=pi&q=Bleomycin.

11. Queensland Health. Queensland Health Guideline: Spirometry (Paediatric)2013: Available from: http://www.health.qld.gov.au/qhpolicy/html/index-a.asp.

12. Swanney MP, Eckert B, Johns DP, Burton D, Crockett AJ, Guy P, et al. Spirometry Training Courses – A Position Paper of the Australian and New Zealand Society of Respiratory Science and the Thoracic Society of Australia and New Zealand. 2004: Available from: http://www.anzsrs.org.au/spirotrainingposition.pdf

13. Lindemann H. Body plethysmographic measurements in children with an accompanying adult. Respiration. [In Vitro]. 1979;37(5):278-81.

14. Coates AL, Peslin R, Rodenstein D, Stocks J. Measurement of lung volumes by plethysmography. Eur Respir J. 1997 Jun;10(6):1415-27.

15. Salamon E, Gain K, Hall G. Wait time effect on repeat multiple breath nitrogren washout FRC. [Paper presented at: European Respiratory Society Annual Congress; 2010 September 18-22; Barcelona, Spain ]: European Respiratory Society,; 2010 [16/02/2012]; Available from: https://www.ersnetsecure.org/public/prg_congres.abstract?ww_i_presentation=48377.

16. Brown R, Leith DE, Enright PL. Multiple breath helium dilution measurement of lung volumes in adults. Eur Respir J. [Research Support, Non-U.S. Gov't

Research Support, U.S. Gov't, P.H.S.]. 1998 Jan;11(1):246-55.

17. Ruppel G. Manual of pulmonary function testing. St. Louis, Mo.: Mosby; 1998.

18. Macintyre N, Crapo RO, Viegi G, Johnson DC, van der Grinten CPM, Brusasco V, et al. Standardisation of the single-breath determination of carbon monoxide uptake in the lung. Eur Respir J. 2005 Oct;26(4):720-35.

19. Cotes JE, Chinn DJ, Miller MR. Lung Function Physiology, Measurement and Application in Medicine. 6th ed: Blackwell Publishing; 2006.

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