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

By: By:

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

Yazd University of Medical SciencesYazd University of Medical Sciences

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 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

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

Contraindications of SpirometryContraindications of Spirometry

• Uncontrolled hypertension Uncontrolled hypertension • Suspected presence of active TB or other Suspected presence of active TB or other

communicable respiratory disease communicable respiratory disease • Thoracic or abdominal surgery within recent 3 Thoracic or abdominal surgery within recent 3

wks wks • MI or unstable angina within recent 6 wks MI or unstable angina within recent 6 wks • Respiratory distress Respiratory distress • Active hemoptysis Active hemoptysis • Recent eye/ear surgery Recent eye/ear surgery • Abdominal or thoracic aortic aneurysmAbdominal or thoracic aortic aneurysm

Interfering conditionInterfering condition

• Acute illness or cold during the past Acute illness or cold during the past few days few days

• Any respiratory infection during the Any respiratory infection during the past 3 weeks past 3 weeks

• Heavy meal during the past 1-2 hour Heavy meal during the past 1-2 hour

• Cigarette smoking during the past 1 Cigarette smoking during the past 1 hour hour

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 mid-expiratory flow)(maximum mid-expiratory flow)

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

FVCFVC

• Definition:Definition:– maximal amount of air that can be exhaled maximal amount of air that can be exhaled

forcefullyforcefully after a maximal inspiration or the after a maximal inspiration or the most air a person can blow out after taking the most air a person can blow out after taking the deepest possible breath. deepest possible breath.

FEV1FEV1

• Definition:Definition:– The volume of air exhaled during the first second of a The volume of air exhaled during the first second of a

forcedforced expiratory maneuver expiratory maneuver

FEV1/FVC%FEV1/FVC%

• Definition: Definition: – The value expresses the volume of air the worker exhales in one The value expresses the volume of air the worker exhales in one

second as a percent of the total volume of air that is exhaled.second as a percent of the total volume of air that is exhaled.

Spirometry Performance StepsSpirometry Performance Steps

• Equipment performance criteriaEquipment performance criteria

• Equipment quality control ( calibration & leak ) Equipment quality control ( calibration & leak )

• Contraindications & interfering conditionContraindications & interfering condition

• Age, height, race, genderAge, height, race, gender

• Selection of appropriate reference valueSelection of appropriate reference value

• Patient maneuverPatient maneuver

• Acceptability criteriaAcceptability criteria

• Reproducibility criteriaReproducibility criteria

• Selection of best curve and best resultSelection of best curve and best result

• interpretationinterpretation

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

Measuring lung volumes (RV, Measuring lung volumes (RV, FRC, TLC)FRC, TLC)

• Nitrogen washoutNitrogen washout

• Helium dilutionHelium dilution

• Body plethysmographyBody plethysmography

• Diffusing CapacityDiffusing Capacity

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

Case 1Case 1

• A A 60 year old man with a 60 60 year old man with a 60 pack/year smoking history pack/year smoking history and dyspnea on exertionand dyspnea on exertion

• FVC =FVC = 73% 73% , FEV1 = , FEV1 = 23% 23% FEV1/FVC = FEV1/FVC = 25% 25% FEF25-75 = FEF25-75 = 6% 6% TLC = TLC = 150% 150% DLCO = DLCO = 19%19%

AnswerAnswer

• This patient has emphysemaThis patient has emphysema. . His His FEV1FEV1// FVC ratio is < 70% which indicates FVC ratio is < 70% which indicates obstructionobstruction. . His FEV1 is < 34% of predicted His FEV1 is < 34% of predicted which indicates very severe obstructionwhich indicates very severe obstruction. . His His TLC is elevated and his diffusing capacity is TLC is elevated and his diffusing capacity is very lowvery low. . We consider PFTs consistent with We consider PFTs consistent with emphysema if there is emphysema if there is (( 11) ) nonnon-- reversible reversible obstruction, obstruction, (( 22) ) elevated lung volumes, elevated lung volumes, (( 33) ) low diffusing capacity, and low diffusing capacity, and (( 44) ) an adequate an adequate smoking historysmoking history

Case 2Case 2

• 50 year old man with a 65 50 year old man with a 65 pack/year smoking history pack/year smoking history and a cough. His chest x-ray and a cough. His chest x-ray shows a diffuse shows a diffuse reticulonodular patternreticulonodular pattern

• FVC =FVC = 6262% % , FEV1 = 42, FEV1 = 42% % FEV1/FVC = 56FEV1/FVC = 56% % FEF25-75 = 11 FEF25-75 = 11% % TLC = 64TLC = 64% % DLCO = 2 DLCO = 29%9%

AnswerAnswer

• First, he is obstructed because the First, he is obstructed because the FEV1FEV1// FVC ratio is < 72%FVC ratio is < 72%. . Second, he is Second, he is restricted since the TLC is < 80%restricted since the TLC is < 80%. . Third, Third, he has a low diffusing capacityhe has a low diffusing capacity. . The The differential diagnosis of combined differential diagnosis of combined restrictive & obstructive defects includes restrictive & obstructive defects includes cystic fibrosis, bronchiectasis, cystic fibrosis, bronchiectasis, lymphangioleimomatosis, eosinophilic lymphangioleimomatosis, eosinophilic granuloma, and interstitial disease granuloma, and interstitial disease + + COPDCOPD. . This patient has eosinophilic This patient has eosinophilic granulomagranuloma

Case 3Case 3

• A A 22 year old woman with 22 year old woman with dyspnea on exertion. She also dyspnea on exertion. She also notes dyspnea when exposed notes dyspnea when exposed to cats. On physical exam, to cats. On physical exam, she is wheezingshe is wheezing

• FVC =FVC = 8383% % , FEV1 = 60, FEV1 = 60% % FEV1/FVC FEV1/FVC = 61= 61% % FEF25-75 = 23 FEF25-75 = 23% % TLC = 100TLC = 100% % DLCO = 122DLCO = 122%%

•

AnswerAnswer

• This is pretty typical for asthmaThis is pretty typical for asthma. . The The FEV1FEV1// FVC ratio is < 75% so she is FVC ratio is < 75% so she is obstructedobstructed. . The FEV1 puts her in the The FEV1 puts her in the moderate obstruction categorymoderate obstruction category. . She is not She is not restricted and the diffusing capacity is restricted and the diffusing capacity is increasedincreased. . The reason why the diffusing The reason why the diffusing capacity is increased in asthma is not fully capacity is increased in asthma is not fully known but it has been suggested that there known but it has been suggested that there is increased pulmonary blood flow, allowing is increased pulmonary blood flow, allowing increased carbon monoxide extraction from increased carbon monoxide extraction from the carbon monoxide inhalationthe carbon monoxide inhalation..

Case 4Case 4

• 43 year old woman with 43 year old woman with progressive dyspnea on progressive dyspnea on exertion. Chest x-ray shows exertion. Chest x-ray shows bilateral reticular infiltrates, bilateral reticular infiltrates, especially in the lung basesespecially in the lung bases

• FVC =FVC = 5151% % , FEV1 = 49, FEV1 = 49% % FEV1/FVC = 78FEV1/FVC = 78% % FEF25-75 = 35 FEF25-75 = 35% % TLC = 52TLC = 52% % DLCO = 51 DLCO = 51%%

AnswerAnswer

• This is characteristic for interstitial This is characteristic for interstitial lung diseaselung disease. . The FEV1The FEV1// FVC ratio is FVC ratio is > 73% so she is not obstructed> 73% so she is not obstructed. . The The TLC is 35% of predicted so she falls TLC is 35% of predicted so she falls in the severe restriction categoryin the severe restriction category. . The The diffusing capacity is low indicating diffusing capacity is low indicating impairment to gas transportimpairment to gas transport