Pulmonary function tests (PFTs) measure how well the lungs work by assessing lung volumes, air flow, and gas exchange. PFTs can help diagnose various respiratory diseases by detecting abnormalities. The tests involve spirometry to measure volumes of air inhaled and exhaled during normal and forced breathing maneuvers. Obstructive diseases reduce air flow, shown by a decreased FEV1 and FEV1/FVC ratio. Restrictive diseases limit lung expansion, shown by a reduced FVC but normal or increased FEV1/FVC ratio. PFTs are useful for evaluating respiratory system function and the effects of treatment.

1. PULMONARY FUNCTION TEST
Rahul AP.
Asst Proff, LIAHS
BPT,MPT MIAP
CRD&ICU Care

2. PFT
• 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. Lung volume and capacities
• Lung vol: are the static vol: of air breathed by
an individual, ie vol: of air present in lung
under specific position of the torax
• 4 lung volumes
• Depends on age, weight, gender and body
position
• 2 or more vol: when combined are capacity

7. Lung volumes
• TV-the vol: of gas exchanged during a relaxed insp:
followed by an exp: 500ml
• IRV-extra vol: of gas that can be inspired above
tidal insp: 3000ml
• ERV-extra vol: of gas that can be expired after a
normal tidal exp: 1000ml
• RV-vol: of gas remain in lungs after a forceful exp:
1500ml

8. • IC-max: amount of gas inspired in to the lungs after a
normal tidal exp: [IC=TV+IRV] 3500ml
• FRC-amount of gas remain in the lungs after normal
exp:[ FRC=ERV+RV] 2500ml
• VC-max: amount of gas expired from the lungs after a
max: insp: [VC=IRV+TV+ ERV] 4500ml
• TLC-max: amount of gas inspired to expand the lungs to
its max:extend [TLC=TV+IRV +ERV +RV] 6000ml
Lung capacity

9. Graph

10. 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

11. Indications/purpose
• Detect disease, It serve as a diagnostic tool
investigation role
• Evaluate severity, extent and monitor the course of
disease
• Evaluate treatment
• Measure effects and result of treatment exposures

12. PFTs can help diagnose
• Asthma
• Chronic bronchitis
• Respiratory infections
• Lung fibrosis
• Bronchiectasis
• Allergy

13. • 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

14. 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.

16. • 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.

17. Lung Factors Affecting Spirometry
• Mechanical properties
• Resistive elements

18. 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

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

20. 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)

21. • 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)
Procedure

22. Normal spirogram

23. 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

24. 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.

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

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

27. 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)

28. Identify an obstructive problem
• Obst: disorders (asthma, copd) air flow
reduces because of narrowing of air ways
• FEV1 is reduced
• Spirogram is continued to 6 sec to empty lung,
FVC also reduced because gas is trapped
behind the obstructed bronchi
• Cardinal feature of obstructive defect is
reduction in the FEV1/FVC ratio

29. • In obstructive diseases (asthma, COPD, chronic
bronchitis, emphysema) FEV1 is diminished because
of increased airway resistance to expiratory flow.
• The FVC may be decreased due to the premature
closure of airway in expiration
• This generates a reduced value (<80%, often 45%).
60-80% -mild
40-60% -moderate
<40% -severe obstructions

30. Obstructive spirogram

31. Obstructive Disorders

32. Restrictive problem
• Restrictive disorders can be cause by disease of the
lung parenchyma (lung fibrosis) and chest wall
disease(kyphoscoliosis)
• This prevent the full expansion of the lungs
therefore FVC may be reduced
• FEV1 will increased because of the stiffness of the
fibrotic lungs increases the expiratory pressure
• Hence expired air comes out very quickly resulting
with a high FEV1/FVC ratio

33. Restrictive spirogram

34. Restrictive Lung Disease

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