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
4.
5.
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
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.
15.
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.
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
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
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
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
