PULMONARY FUNCTION TESTS,spirometer,Respiratory mechanics – Lung parenchymal function/ Gas exchange – Cardiopulmonary interaction Spirometry,LUNG VOLUMES AND CAPACITIES,Tidal Volume (TV),Mechanics of Breathing,Normal spirogram,Forced expiratory volume in 1 second(FEV1),Forced vital capacity (FVC),FEV1/FVC ratio ,N2 Washout Technique,Body Plethysmography,

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