The document discusses pulmonary function tests (PFTs) designed to measure and evaluate lung function, including how well they take in and exhale air and transfer oxygen into the blood. It covers various aspects of PFTs such as spirometry, lung volumes and capacities, and diagnostic applications for respiratory conditions. The text illustrates how PFTs help distinguish between obstructive and restrictive lung problems and highlights important measurement values and their interpretations.

1. By-Dr.Ranjeet Singha,PT(MPT in Neurology)
HAAD Licensed
Associate Professor,
College of Physiotherapy and Medical Sciences,
Guwahati,Assam.

2.  Pulmonary function tests is a generic term used to
 indicate a battery of studies or maneuvers that may
 be performed using standardized equipment to
 measure lung function.
 Pulmonary function tests (PFTs) are a group of tests
 that measure how well your lungs works, how well
 the lungs take in and exhale air, and how efficiently
 they transfer oxygen into the blood

3.  PFT or LFT are useful in assessing the functional
 status of the respiratory system both in
 physiological and pathological condition
 • It is base on the measurement of volumes of air
 breathed in and out in normal breathing and forced
 breathing
 • It is carried out by using a spirometer

6.  Evaluates one or more aspects of the respiratory
 system
 – Respiratory mechanics
 – Lung parenchymal function/ Gas exchange
 – Cardiopulmonary interaction

7. INDICATIONS
 DIAGNOSTIC
 Evaluation of signs &
symptoms‐ chronic
cough, exertional
dyspnea
 Screening at risk pts
 Measure the effect of Ds
on pulmonary function
 PROGNOSTIC
 Assess severity
 Follow response to
therapy
 Determine further
treatment goals
 Evaluating degree of
disability

8. PFTs can help diagnose
 Asthma
 • Chronic bronchitis
 • Respiratory infections
 • Lung fibrosis
 • Bronchiectasis
 • Allergy
 Emphysema
 • Cystic fibrosis
 • Asbestosis which is a
condition caused by
exposure
 to asbestos
 • Sarcoidosis, which is an
inflammation of your
lungs,
 liver, lymph nodes, eyes,
skin, or other tissues
 • Pulmonary tumor

9. Contraindications
 Recent eye surgery
 • Thoracic , abdominal and cerebral aneurysms
 • Active hemoptysis
 • Pneumothorax
 • Unstable angina/ recent MI within 1 month

10. STATIC LUNG VOLUMES AND
CAPACITIES
 SPIROMETRY : CORNERSTONE OF ALL PFTs.
 • John hutchinson – invented spirometer.
 • “Spirometry is a medical test that measures the
 volume of air an individual inhales or exhales as a
 function of time.”
 • CAN’T MEASURE – FRC, RV, TLC

11. Spirometry
 It is an instrument for measuring the air capacity of
 the lungs
 • Measurement of the pattern of air movement in
 and out of the lungs during controlled ventilatory
 maneuvers.
 • spirometre is used to measure the air flow,
 ventilatory regulation, ventilatory mechanics and
 lung volume during a forced expiratory maneuver
 from full inspiration.

14.  Pft used to evaluate physiological aspect of
 breathing from resp:muscle function to the
 diffusion of gas at the alviolar wall.
 • Pft helps physiotherapist to distinguish between
 obstructive and restrictive lung problem and to
 select appropriate treatment
 • It also measure the effect of the given treatment

15. SPIROMETRY‐Acceptability Criteria
 Good start of test‐ without any hesitation
 • No coughing / glottic closure
 • No variable flow
 • No early termination(> 6 sec)
 • No air leak
 • Reproducibility‐ The test is without excessive
variability
 The two largest values for FVC and the two largest
values for FEV1 should vary by no more than 0.2L.

16. Spirometry Interpretation: So what
constitutes normal?
 Normal values vary and depend on:
 I. Height – Directly proportional
 II. Age – Inversely proportional
 III. Gender
 IV. Ethnicity

17. LUNG VOLUMES AND CAPACITIES
 PFT tracings have:
 Four Lung volumes: tidal
 volume, inspiratory reserve
 volume, expiratory reserve
 volume, and residual volume
 Five capacities: inspiratory
 capacity, expiratory capacity,
 vital capacity, functional
residual
 capacity, and total lung
capacity
Addition of 2 or more volumes comprise a
capacity.

18. LUNG VOLUMES
 Tidal Volume (TV):
volume of
 air inhaled or exhaled
with
 each breath during quiet
 breathing (6‐8 ml/kg)
500 ml
 •

19.  Inspiratory Reserve Volume
 (IRV): maximum volume of air
 inhaled from the endinspiratory
 tidal position.3000
 ml
 • Expiratory Reserve Volume
 (ERV): maximum volume of
 air that can be exhaled from
 resting end‐expiratory tidal
 position.1500 ml

20.  Residual Volume (RV):
 – Volume of air remaining
in
 lungs after maximium
 exhalation (20‐25 ml/kg)
 1200 ml
 – Indirectly measured
(FRCERV)
 – It can not be measured
by
 spirometry .

21.  Total Lung Capacity (TLC):
Sum of
 all volume compartments or
 volume of air in lungs after
 maximum inspiration (4‐6 L)
 • Vital Capacity (VC): TLC
minus RV
 or maximum volume of air
 exhaled from maximal
inspiratory
 level. (60‐70 ml/kg) 5000ml. VC
~
 3 TIMES TV FOR EFFECTIVE
 COUGH

22.  • Inspiratory Capacity (IC): Sum of
 IRV and TV or the maximum
 volume of air that can be inhaled
 from the end‐expiratory tidal
 position. (2400‐3800ml).
 • Expiratory Capacity (EC): TV+ ERV

23.  Functional Residual
Capacity
 (FRC):
 – Sum of RV and ERV or the
 volume of air in the lungs at
 end‐expiratory tidal
 position.(30‐35 ml/kg) 2500
ml

24.  – Decreases
 1.in supine position(0.5‐1L)
 2.Obese pts
 3.Induction of anesthesia: by 16‐
 20%

25. Graph

26. Mechanics of Breathing
 • Inspiration
 Active process
 • Expiration
 Quiet breathing: passive
 Can become active
 Pulmonary Function Tests Evaluates 1 or more
 major aspects of the respiratory system
 • Lung volumes
 • Airway function
 • Gas exchange

27.  Lung Factors Affecting Spirometry
 • Mechanical properties
 • Resistive elements

28. Mechanical Properties
 • Compliance
 – Describes the stiffness of the lungs
 – Change in volume over the change in
 pressure
 • Elastic recoil
 – The tendency of the lung to return to it’s
 resting state
 – A lung that is fully stretched has more
 elastic recoil and thus larger/ maximal flows
 of gas

29. Resistive Properties
 Affected by:
 Lung volume
 Age
 Sex
 Height
 Weight
 Race
 Disease
 Bronchial smooth muscles

30. PFT procedure
 • Forced expiratory maneuver is the common clinical
 approach
 • Results are found in patients chart/moniter
 • Common spirometric values areFEV1 and FVC
 FEV1/FVC ratio
 • Lung volume and peak expiratory flow rate (PEF or
 PEFR) are measured to differentiate obstructive or
 restrictive problems
 • Forced expiratory flow (FEF)

31. Procedure
 Sit up straight
 • Get a good seal around the mouth piece
 • Rapid inhale maximally
 • Without any delay blow out as hard as fast as
 possible (blast out)
 • Continue the exhale until the patient can`t
 blow no more
 • Expiration should continue at least 6sec (in
 adult) and 3 sec (children under 10yrs)
 • Repeat at least 3 technically acceptable times
 (without cough, air leak and false start)

32. Normal spirogram

33. How to interpret abnormal PFT
 If FVC&FEV1 is less than 80% (total vol:of air
 expelling is approx: 80% with in 1sec ie; FEV1)
 • Suggestions of some pathology, at this point
 and can`t decide obstructive/ restrictive
 problem

34. Forced expiratory volume in 1 second
(FEV1)
 • FEV1 is the volume of air that can forcibly be blown
 out in one second, after full inspiration.
 • Average values for FEV1 in healthy people depend
 mainly on sex and age height and mass.
 • Values between 80% and 120% are considered
 normal.

35.  Forced vital capacity (FVC)
 • Forced vital capacity(FVC) is the volume of air
 that can forcibly be blown out after full
 inspiration

36.  FEV1/FVC ratio (FEV1%)
 • FEV1/FVC (FEV1%) is the ratio of FEV1 to FVC.
 In healthy adults this should be approximately
 75–80%.

37.  Forced expiratory flow (FEF)
 • Forced expiratory flow (FEF) is the flow (or speed)
 of air coming out of the lung during the middle
 portion of a forced expiration.
 • generally defined by fraction, The usual intervals
 are 25%, 50% and 75% (FEF25, FEF50 and FEF75)

38. Measuring RV, FRC
 It can be measured by
 – nitrogen washout technique
 – Helium dilution method
 – Body plethysmography

39. N2 Washout Technique
 The patient breathes 100% oxygen, and all the
 nitrogen in the lungs is washed out.
 • The exhaled volume and the nitrogen
 concentration in that volume are measured.
 • The difference in nitrogen volume at the initial
 concentration and at the final exhaled
 concentration allows a calculation of
 intrathoracic volume, usually FRC.

40. Helium Dilution technique
 Pt breathes in and out from a reservoir with known
 volume of gas containing trace of helium.
 • Helium gets diluted by gas previously present in
lungs.

41. Body Plethysmography
 • Plethysmography (derived from greek word meaning
 enlargement).
 • Based on principle of BOYLE’S LAW(P*V=k)
 • Priniciple advantage over other two method is it
 quantifies non‐ communicating gas volumes

42.  A patient is placed in a sitting
 position in a closed body box
 with a known volume
 • The patient pants with an
 open glottis against a closed
 shutter to produce changes
 in the box pressure
 proportionate to the volume
 of air in the chest.
 • As measurements done at
 end of expiration, it yields
 FRC

43. FORCED SPIROMETRY/TIMED
EXPIRATORY
SPIROGRAM
 Includes measuring:
 • pulmonary mechanics – to
 assess the ability of the lung to
 move large vol of air quickly
 through the airways to identify
 airway obstruction
 • FVC
 •FEV1
 •Several FEF values
 •Forced inspiratory rates(FIF’s)
 •MVV

44. FORCED VITAL CAPACITY
 • The FVC is the maximum volume of air that can be
 breathed out as forcefully and rapidly as possible
 following a maximum inspiration.
 • Characterized by full inspiration to TLC followed by
 abrupt onset of expiration to RV
 • Indirectly reflects flow resistance property of
 airways.

46. FVC
 Interpretation of % predicted:
 80-120% Normal
 70-79% Mild reduction
 50%-69% Moderate reduction
 <50% Severe reduction

47. Measurements Obtained from the
FVC
Curve and their significance
 Forced expiratory volume
 in 1 sec(FEV1 )‐‐‐the
 volume exhaled during
 the first second of the
 FVC maneuver.
 • Measures the general
 severity of the airway
 obstruction
 • Normal is 3‐4.5 L

49. Measurements Obtained from the
FVC
Curve and their significance
 FEV1 – Decreased in both obstructive & restrictive lung
 disorders(if patient’s vital capacity is smaller than
predicted
 FEV1).
 FEV1/FVC – Reduced in obstructive disorders.
 Interpretation of % predicted:
 >75% Normal
 60%‐75% Mild obstruction
 50‐59% Moderate obstruction
 <49% Severe obstruction

50. Normal Spirometry

51. Spirometry Patterns