Pulmonary function tests (PFTs) are a group of standardized maneuvers and measurements used to diagnose and monitor pulmonary diseases and assess treatment effectiveness. PFTs measure lung volumes, capacity, flows, and gas exchange. Key tests include spirometry, which measures volumes and flows, and diffusion capacity testing, which assesses the alveolar-capillary membrane. PFTs can distinguish between obstructive diseases like asthma, which reduce expiratory flows, and restrictive diseases like fibrosis, which decrease lung volumes and capacity. The results of PFTs are used to diagnose pulmonary abnormalities, determine disease severity, and monitor response to treatment.

1. PULMONARY FUNCTION TEST
DR.MD.IMRAN MEHDI
ERA’ LUCKNOW MEDICAL COLLEGE
LUCKNOW

2. DEFINITION
• PFT’S are a group of maneuvers carried out using standardized
equipments to diagnose , determine the nature , progress and severity of
an underlying pulmonary disease as well as to assess the effectiveness of
treatment.

3. GOALS
 To predict the presence of pulmonary dysfunction
To know the functional nature of disease (obstructive or restrictive. )
To assess the severity of disease
To assess the progression of disease
To assess the response to treatment
To identify patients at increased risk of morbidity and mortality,
undergoing pulmonary resection.

4. Continue…
To wean patient from ventilator in icu.
Medicolegal- to assess lung impairment as a result of occupational
hazard.
Epidemiological surveys- to assess the hazards to document
incidence of disease
To identify patients at perioperative risk of pulmonary complications

5. CLASSIFICATION
STATIC FUNCTION TESTS: measure volumes and capacities e.g. body
plethysmography
DYNAMIC FUNCTION TESTS: measure flow and airway resistance e.g.
spirometry
DIFFUSION CAPACITY: assess the alveolar- capillary membrane
RESPIRATORY MUSCLE STRENGTH
CARDIOPULMONARY PULMONARY EXERCISE TEST
METABOLIC measurements.

6. INDICATIONS
DIAGNOSTIC:
• to evaluate symptoms , signs or abnormal laboratory tests .
• to measure the effect of disease on pulmonary function: obstructive or
restrictive
• to assess pre-operative risk
• part of routine physical examinations
• to assess health status before enrollment in strenuous physical activity
programs
• to screen individuals at risk of having pulmonary disease.

7. Continue…
MONITORING:
• to assess therapeutic interventions:( bronchodilator therapy)
• to assess the course of diseases affecting lung function
( pulmonary, obstructive, interstitial lung disease, cardiac disease
neuromuscular disease, to monitor persons in occupations with
exposure to injurious agents.)

8. CONTRAINDICATIONS
• Hemoptysis of unknown origin
• Pneumothorax
• Recent myocardial infarction
• Unstable angina pectoris
• Thoracic, abdominal and cerebral aneurysm
• Recent abdominal or thoracic surgical procedure

9. Continue…
• Pt.with h/o syncope associated with forced exhalation.
• Recent eye surgery.

10. HOW WE DO PFT?
• BED SIDE PFT.
• SPIROMETRY.
• DIFFUSION CAPACITY.

11. BED SIDE PFT
• Sabrasez breath holding test.
• Snider’s match blowing test.
• Cough test.
• Watch & stethoscope test(FORCED EXPIRATORY TIME)
• Wheeze test.
• Wright peak flow meter test.
• Debono whistle blowing test.
• Single breath count test.

12. SABRASEZ BREATH HOLDING TIME
• Ask the patient to take a DEEP BREATH & hold it as long as possible.
1. >25 SEC.‐NORMAL Cardiopulmonary Reserve (CPR).
2. 15‐25 SEC‐ LIMITED CPR.
3. <15 SEC‐ VERY POOR CPR.

13. SNIDER’S MATCH BLOWING TEST
• Ask to blow a match stick from a distance of 6” (15 cms) with‐
 Mouth wide open
 Chin rested/supported
 No purse lipping
 No head movement
 Mouth and match at the same level

14. Continue…
MEASURES Maximum Breathing Capacity.
DISTANCE MBC
• 9” >150 L/MIN.
• 6” >60 L/MIN.
• 3” > 40 L/MIN

15. COUGH TEST
• Ask the patient to take deep inspiration & cough once.
• Test is POSITIVE if the 1st cough leads to recurrent coughing.

16. WATCH & STETHOSCOPE TEST
After deep breath, exhale maximally and forcefully & keep stethoscope over
trachea & listen.
• NORMAL FET – 3‐5 SECS.
• OBS.LUNG DIS. ‐ > 6 SEC
• RES. LUNG DIS.‐ < 3 SEC

17. WHEEZE TEST
• Patient is asked to take five deep inspirations/expirations.
• pt is auscultated between the shoulder blades posteriorly to determine the
presence or absence of wheeze.

18. WRIGHT PEAK FLOWMETER TEST
• Measures PEFR (Peak Expiratory Flow Rate)
• NORMAL : MALES‐ 450‐700 L/MIN.
FEMALES‐ 350‐500 L/MIN.

19. DEBONO WHISTLE BLOWING TEST
• MEASURES PEFR.
• PRINCIPLE: for a given size of a leak hole a minimum rate of
airflow is required to sound the whistle.
 The pt blows forcibly into the cardboard mouthpiece initially with the
smallest leak hole & then with gradually increasing size till the whistle
cannot be sounded.
 The last size of the leak hole at which a whistle can be obtained is the pt’
PEFR which can be read from the scale.

20. SINGLE BREATH COUNT TEST
• Ask the patient to count out loud numbers from 1 onwards after maximum
inspiration.
• Normal individual can count upto 50.
• Less than 15 indicates severe impairment of vital capacity.

21. SPIROMETRY
• Spirometry is a medical test that measures the volume of air an individual
inhales or exhales as a function of time.
• John hutchinson – invented spirometer.
• CAN’T MEASURE – FRC, RV, TLC

22. Continue…
FRC, RV & TLC CAN BE MEASURED BY:
Nitrogen washout technique.
Helium dilution method.
 Body plethysmography.

23. Continue…
• Simple, office based , Measures flow, volumes
• Volume vs. Time
• Can determine:
 Forced expiratory volume in one second (FEV1)
 Forced vital capacity (FVC)
 FEV1/FVC
 Forced expiratory flow 25%-75% (FEF25-75)

24. Continue…
• SPIROMETRY done to differentiate between OBSTRUCTIVE &
RESTRICTIVE LUNG DISEASE.
• Measures the rate at which the lungs change volume during quiet and
forced breathing maneuvers.
• Can only measure lung volume compartments that exchange gases with
the atmosphere.
• Often done as a maximal expiratory maneuver.

25. ATS (American Thoracic Society) STANDARDS
1 No coughing: especially during first second of FVC
2 Good start of test: <5% of FVC exhaled prior to a max
expiratory effort.
3 No early termination of expiration: exhalation time of six
seconds or a plateau of 2 seconds.
4. No variable flows: flow rate should be consistent and as fast as
possible throughout exhaled VC
5. Good reproducibility or consistency of efforts: 2 best FVC's
and 2 best FEV1's should be within 0.150 L of each other.

26. COMPONENTS
FORCED VITAL CAPACITY.
FORCED EXPIRATORY VOLUME.
FORCED EXPIRATORY FLOW.
MAXIMUM VOLUNTARY VENTILATION.
FLOW VOLUME LOOPS.
LUNG VOLUME & CAPACITIES.

27. FORCED VITAL CAPACITY
• Performed by having the patient inhale maximally & then forcefully
exhaling as rapidly & thoroughly as possible into a spirometer.
• Normal people can exhale in less than 3 seconds.
• Normal value is 80-120% of predicted.
• 80-120% : normal
• 70-79%: mild reduction.
• 50-69 % : moderate reduction.
• Less than 50% : severe reduction

28. FORCED EXPIRATORY VOLUME
• Volume of air forcefully expired from maximal inspiration in the first
second.
• It reflects the mechanical properties of both the large and medium sized
airways.
• Can be decreased by both obstructive & restrictive lung diseases.
Normal Value:
- 75-85% within 1 second.
 95% within 2 second.
 97% within 3 second.

29. FORCED EXPIRATORY FLOW AT 25-75%
OF VITAL CAPACITY
• It is the mean FEF during middle half of FVC measured in L/SEC.
• It reflects effort independent expiration & status of small airways( less
than 2mm diameter).
• It is an indicator of obstruction & depends on FVC.

30. Continue…
Interpretation of percentage predicted:
• Greater than 60% : normal
• 40-60% : mild obstruction.
• 20-40% : moderate.
• Less than 10% : severe obstruction.

31. PEAK EXPIRATORY FLOW RATE
• Gives the maximum flow rate achieved during FVC maneuver.
• Sensitive test for obstructive lung disease.
• Useful to assess effectiveness of treatment.
• Normal values: 4-5 L/sec.

32. MAXIMUM VOLUNTARY VENTILATION
• Maximum amount of air that can be inhaled & exhaled with in 1
MINUTE.
• It reflects the status of respiratory muscle strength, lung compliance &
airway resistance.
• It is effort dependent.
• Normal value:
Male: 140-180 L.
Female: 80-120 L.

33. FLOW VOLUME LOOPS
• Graphical analysis of flow at various
lung volumes.
• First 1/3rd of expiratory flow is effort
dependent and the final 2/3rd near the
RV is effort independent.
• Inspiratory curve is entirely effort
dependent.

34. NORMAL OBSTRUCTIVE RESTRICTIVE

36. OBSTRUCTIVE LUNG DISEASE
(Hallmark FEV1)
RESTRICTIVE LUNG DISEASE
(Hallmark TLC)
Bronchial Asthma.
Chronic Bronchitis.
Emphysema.
Bronchiectasis.
Bronchiolitis.
Cystic Fibrosis.
Parenchymal:
Asbestosis,Silicosis,Sarcoidosis,Pneumoconiosis,
Idiopathic Pulmonary fibrosis.
Non parenchymal:
Kyphosis,Ankylosing spondylitis,Mysthenia
Gravis,Gullian Barry syndrome,Diaphragmatic
palsy,Mesothelioma.

37. VALUE OBSTRUCTIVE
Airway obstruction to
expiratory flow
RESTRICTIVE
Decrease in all lung volumes
TLC
RV
FVC
FEV1
FEV1/FVC
FEF 25-75%
DC
FRC
Normal/increase
Increase
Normal/increase
Decrease
Decrease
Decrease
Normal(decrease in emphysema)
Normal/increase
Decrease
Decrease
Decrease
Decrease
Normal
Normal
Decrease
Decrease

38. Classification of COPD Severity by
Spirometry
STAGE SEVERITY SPIROMETRY
FEV1/FVC FEV1%
PREDICTE
D
Stage 1 Mild < 0.70 > 80%
Stage 2 Moderate < 0.70 50-80 %
Stage 3 Severe < 0.70 30-50%
Stage 4 Very Severe < 0.70 < 30%

39. BRONCHO DILATOR REVERSIBILITY
TESTING
• Tests should be performed when pts. Are clinically stable and free from
respiratory infections.
• FEV1 should be measured twice before bronchodilator given.
• An increase in FEV1 that is both greater than 200 ml and 12% above the
pre-bronchodilator FEV1 is considered significant.

40. LUNG VOLUME & CAPACITIES

41. CARBON MONOXIDE DIFFUSING
CAPACITY
• It is a test that measures the rate of gas transfer across alveolar capillary
membrane.
• Most widely used test is SINGLE BREATH METHOD.
• Normal value: 17-25 ml/min/mm of Hg.

42. THANK YOU