Spirometry (Pulmonary Function Tests) By: A. H. Mehrparvar, M.D.

Spirometry Spirometry (Pulmonary Function Tests)(Pulmonary Function Tests)

By: By:

A. H. Mehrparvar, M.D.A. H. Mehrparvar, M.D.

ReferencesReferences

1. M. R. Miller, et al. “ATS Standardisation of Spirometry”. 1. M. R. Miller, et al. “ATS Standardisation of Spirometry”. Eur Eur Respir J.Respir J. 2005, 26: 319-338. 2005, 26: 319-338.

2. “Lung Function Testing: Selection of Reference Values and2. “Lung Function Testing: Selection of Reference Values and

Interpretative Strategies”, ATS, 2003.Interpretative Strategies”, ATS, 2003.

3. NIOSH Spirometry Training Guide, 20033. NIOSH Spirometry Training Guide, 2003..

4. 4. Spirometry HandbookSpirometry Handbook. National Asthma Council (Australia), . National Asthma Council (Australia), 2004.2004.

DefinitionDefinition

A physiological test for measuring A physiological test for measuring volumes inhaled or exhaled by an volumes inhaled or exhaled by an individual as a function of timeindividual as a function of time

IndicationsIndications

• Not a screening test for general Not a screening test for general populationpopulation

• Diagnostic Diagnostic

• MonitoringMonitoring

• Impairment evaluationImpairment evaluation

• Public healthPublic health

Indications (diagnostic)

• Evaluation of symptoms and signsEvaluation of symptoms and signs• Measuring the effect of dis. on Measuring the effect of dis. on

pulmonary functionpulmonary function• Screening individuals at risk for Screening individuals at risk for

pulmonary dis.pulmonary dis.• Assess preoperative riskAssess preoperative risk• Assess health status before physical Assess health status before physical

activities (e.g. work)activities (e.g. work)

Indications (monitoring)

• Assess therapeutic interventionAssess therapeutic intervention

• Monitor people exposed to injurious Monitor people exposed to injurious agentsagents

Spirometry standards

• ATSATS (American Thoracic Society) (American Thoracic Society)

• ERSERS (European Respiratory Society) (European Respiratory Society)

Spirometry standardisation steps

Equipment performance criteria

Equipment validation

Quality control

Subject maneuvers

Measurements procedures

Acceptability

Repeatability

interpretation

Spirometry maneuvers

• FVCFVC

• VC and ICVC and IC

• PEFPEF

• MVVMVV

FVC maneuver

• Requirements of spirometer:Requirements of spirometer:1. Accumulating volume for at least 15 s

2. Measuring volumes at least 8 lit (BTPS)

3. Accuracy of at least ± 3% or ±0.050 lit with flows between 0 and 14 lit/s

4. Showing both volume-time and flow-volume curves

5. Showing EV value

Test procedure

1.1. Maximal inspirationMaximal inspiration

2.2. A blast of exhalationA blast of exhalation

3.3. Complete exhalation to the end of Complete exhalation to the end of testtest

Spirometry curves

Spirometric indices

• FVC FVC (forced vital capacity)(forced vital capacity)

• FEVFEV1 1 (forced expiratory volume in 1 s)(forced expiratory volume in 1 s)

• FEVFEV11/FVC/FVC

• FEVFEVt t (forced expiratory volume in t s)(forced expiratory volume in t s)

• FEFFEF25-75 25-75 (maximum midexpiratory flow)(maximum midexpiratory flow)

• PEF PEF (peak expiratory flow)(peak expiratory flow)

Within maneuver evaluation

• Start of test criteriaStart of test criteria- back extrapolation- back extrapolation (EV < 5% of FVC or 150 ml)(EV < 5% of FVC or 150 ml)

● ● End of test criteriaEnd of test criteria- the subject cannot or should not continue- the subject cannot or should not continue

- exhalation at least 6s (in children under 10, 3s)- exhalation at least 6s (in children under 10, 3s)

- no change in volume (<0.025 lit) for at least 1s- no change in volume (<0.025 lit) for at least 1s

* In obstruction or older subjects more than 6s exhalation (till * In obstruction or older subjects more than 6s exhalation (till 15s)15s)

Acceptability

● ● Start of test criteriaStart of test criteria

● ● End of test criteriaEnd of test criteria

● ● cough especially during first secondcough especially during first second

● ● Valsalva maneuver (glottis closure) Valsalva maneuver (glottis closure)

● ● Leak from the mouthLeak from the mouth

● ● Obstruction of the mouthpieceObstruction of the mouthpiece

● ● Extra breath during the maneuverExtra breath during the maneuver

Repeatability

• At least three acceptable maneuversAt least three acceptable maneuvers

Maximum difference between the largest and next Maximum difference between the largest and next largest FVC largest FVC andand FEV FEV11 = 150ml (If FVC <1lit, this = 150ml (If FVC <1lit, this value is 100ml)value is 100ml)

● ● At the most eight tests should be At the most eight tests should be performedperformed

Flow chart of criteria

Perform FVC

Acceptability criteria

3 acceptable maneuvers

Repeatability criteria

Largest FVC and largest FEV1

Maneuver with largest FVC + FEV1 for other indices

Reversibility testing

1.1. Stop drugs (short-acting for 4 h, Stop drugs (short-acting for 4 h, long-acting for 12h) before testlong-acting for 12h) before test

2.2. Stop smoking for 1 h. before testStop smoking for 1 h. before test3.3. Perform baseline testPerform baseline test4.4. Administer drugAdminister drug5.5. Perform test after 10 – 15 min. (for Perform test after 10 – 15 min. (for

salbutamol) or after 30 min. (for salbutamol) or after 30 min. (for ipratropium)ipratropium)

Reversibility criteria

1. VC (forced or slow) and FEV1 the primary indices for bronchodilator response.

2. A 12% increase, and a 200-ml increase in either FVC or FEV1

3. FEF25-75 should be used secondarily in evaluating bronchodilator response.

4. Ratios such as FEV1/VC should not be used to judge bronchodilator response.

VC maneuver

1.1. Two types (IVC and EVC)Two types (IVC and EVC)

2.2. Perform this test prior to FVCPerform this test prior to FVC

3.3. Perform not more than 4 tests (at Perform not more than 4 tests (at least 1 min. apart)least 1 min. apart)

4.4. Surely use nose clipSurely use nose clip

Interpretation

Key Notes

1. be conservative in suggesting a specific diagnosis based only on pulmonary function abnormalities.

2. Interpret borderline normal values with caution.

3. First step = to evaluate and comment on the quality of the tests.

Key Notes

4. The number of test indices (e.g., FVC, FEV1, etc.) used in interpretation should be limited to avoid an excessive number of false positive results.

5. The primary guides for spirometry interpretation should be VC (slow or forced), FEV1, and FEV1/VC.

6. FEV1/VC should be the primary guide for distinguishing obstructive from nonobstructive patterns.

Key Notes

7. If FEV1/VC is borderline, use Instantaneous and mid flows to confirm airway obstruction.

8. Don’t use FEF25-75 and the instantaneous flows to diagnose small airway disease.

9. The pattern of a low FEV1/VC and greater than average VC and FEV1 should be recognized as one that may occur in healthy individuals.

Key Notes

10. The severity of airway obstruction should be based on FEV1.

11. When FEV1 and FEV1/VC are normal, don’t use FEF25-75 for grading the severity of obstruction.

12. A reduced VC and normal FEV1/VC suggest but not diagnose the presence of restriction.

13. The severity of restriction should be based on TLC. If VC is used, severity may be based on VC.

Lower Limits of Normal

1. Normal ranges should be based on calculated fifth percentiles.

2. Lower limits of normal are variable.

3. The use of 80% of predicted for adult pulmonary function parameters is not recommended. This criterion works only for average persons and for a limited number of parameters.

LLN

• FEVFEV11 and FVC = 80% and FVC = 80%

• FEVFEV11/FVC = 70-75%/FVC = 70-75%

• FEFFEF25-7525-75 = 50-60% = 50-60%

http://www.nationalasthma.org.au/publications/spiro/graph/f5.htm

Interpretation

A. Normal: both the VC and the FEV1/VC ratio are normal.

B. Obstructive: FEV1/VC ratio is below the normal range.

The severity of the abnormality is graded:- % Pred FEV1 > 100 = May be a

physiological variant- % Pred FEV1 < 100 and > 70 = Mild- % Pred FEV1 < 70 and > 60 = Moderate- % Pred FEV1 < 60 and > 50 = Moderately

severe- % Pred FEV1 < 50 and > 34 = Severe- % Pred FEV1 < 34 = Very severe

Interpretation

C. Restrictive: This is most reliably interpreted on the basis ef TLC. If this is not available, one may interpret a reduction in the VC without a reduction of the FEV1/VC ratio as a restriction

The severity of the abnormality might be graded as follows:

- % Pred VC < LLN and > 70 = mild- % Pred VC < 70 and > 60 = Moderate- % Pred VC < 60 and > 50 = Moderately

severe- % Pred VC < 50 and > 34 = Severe- % Pred VC < 34 = Very severe

VCVCFRCFRC

RVRV

TLCTLC

VVtt

NormalNormal

RVRV

ERVERV

ICIC

RVRV

VCVC

TLCTLC

RVRV

VCVC

RVRV

VCVC

RVRV

VCVC

NormalNormalObstructiveObstructive RestrictiveRestrictive

Vital capacity is reduced in both obstructive and restrictive diseases

yy eess nn oo

yy eess nn oo

yy eess nn oo

An Algorithm for SpirometryAn Algorithm for SpirometryIs maneuver acceptable? Is maneuver acceptable?

Is the FEV1/FVC lower Is the FEV1/FVC lower than predicted?than predicted?

Interpretation may be Interpretation may be limited by falsely low limited by falsely low FVCFVC

This is the definition of This is the definition of obstructionobstructionMildMild FEV1 >70%FEV1 >70%ModerateModerate FEV1 60-70%FEV1 60-70%Mod severeMod severe FEV1 50-60%FEV1 50-60%SevereSevere FEV1 <50%FEV1 <50%Very severeVery severe FEV1 <40%FEV1 <40%

Is FVC reduced?Is FVC reduced?

Restriction Restriction maymay be present; be present; Need TLC to definitively Need TLC to definitively diagnose restrictiondiagnose restriction

Lung volumes:Lung volumes:Severity determined bySeverity determined bythe reduction in TLCthe reduction in TLCMildMild 65-80%65-80%ModerateModerate 50-65%50-65%SevereSevere <50%<50%

Spirometry:Spirometry:Severity is determinedSeverity is determined by the reduction in VCby the reduction in VCMildMild 70-80%70-80%ModerateModerate 60-70%60-70%SevereSevere <60%<60%

Normal pulmonary Normal pulmonary mechanicsmechanics

RestrictionRestriction

Extrathoracic/upper airway obstruction (stridor)

Fixed upper airway obstruction

Case 1

• A 38 year-old maleA 38 year-old male

• Height: 171, weight: 82Height: 171, weight: 82

• FVC = 4.53 (100%)FVC = 4.53 (100%)

• FEVFEV11 = 3.35 (89%) = 3.35 (89%)

• FEVFEV11/FVC = 74%/FVC = 74%

• FEFFEF25-7525-75 = 2.85 (65%) = 2.85 (65%)

Case 2



• FVC = 4.51 (97%)FVC = 4.51 (97%)

• FEVFEV11 = 3.18 (86%) = 3.18 (86%)

• FEVFEV11/FVC = 70.50%/FVC = 70.50%

• FEFFEF25-7525-75 = 2.26 (58%) = 2.26 (58%)

Case 3



• FVC = 4.77 (115%)FVC = 4.77 (115%)

• FEVFEV11 = 3.50 (101%) = 3.50 (101%)

• FEVFEV11/FVC = 73.40%/FVC = 73.40%

• FEFFEF25-7525-75 = 2.74 (66%) = 2.74 (66%)

Case 4



• FVC = 3.81 (81%)FVC = 3.81 (81%)

• FEVFEV11 = 2.38 (63%) = 2.38 (63%)

• FEVFEV11/FVC = 62.5%/FVC = 62.5%

• FEFFEF25-7525-75 = 1.72 (41%) = 1.72 (41%)

Case 5



• FVC = 5.82 (111%)FVC = 5.82 (111%)

• FEVFEV11 = 4.98 (116%) = 4.98 (116%)

• FEVFEV11/FVC = 85.6%/FVC = 85.6%

• FEFFEF25-7525-75 = 5.25 (114%) = 5.25 (114%)

Case 6



• FVC = 3.93 (76%)FVC = 3.93 (76%)

• FEVFEV11 = 2.75 (66%) = 2.75 (66%)


• FEFFEF25-7525-75 = 1.91 (43%) = 1.91 (43%)

Case 7



• FVC = 4.56 (121%)FVC = 4.56 (121%)

• FEVFEV11 = 3.10 (102%) = 3.10 (102%)


• FEFFEF25-7525-75 = 1.83 (51%) = 1.83 (51%)

Spirometry (Pulmonary Function Tests) By: A. H. Mehrparvar, M.D.

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