The document provides information about pulmonary function tests (PFTs). PFTs are used to screen for and evaluate obstructive and restrictive lung diseases. They can assess lung function prior to surgery and the effectiveness of treatment. The document defines various lung volumes and capacities measured by PFTs like tidal volume, vital capacity, total lung capacity. It also describes tests like spirometry that measure expiratory volumes and flow rates. Flow-volume curves generated from spirometry help distinguish obstructive from restrictive lung diseases. Diffusion tests evaluate gas exchange across the alveolar membrane while bronchoprovocation tests assess airway reactivity.

1. PULMONARY
FUNCTION
TEST

2. PURPOSE OF PULMONARY FUNCTION TEST
• Pulmonary function test has been a major step for forward in
assessing the functional status of the lungs.
Pulmonary function tests are used for the following
• screening for the presence of obstructive and restrictive
diseases.
• Evaluating the patient prior to surgery especially those who are
older than 60-65 years of age and have history of smoking,
cough or wheezing.
• Documenting the effectiveness of therapeutic intervention.

3. NORMAL VALUES CHANGES WITH:
Age
As a person age the natural elasticity of the lungs
decrease. This results in smaller lungs volume and capacities
as we age.
Gender
Male have larger lung volume and capacities than female.
Body weight and size:
A small man will have smaller PFT result than a man of
same age who is much larger.
Race
Alters PFT values.

4. TERMINOLOGY AND DEFINITION
A.LUNG VOLUME TESTS:
1.TIDAL VOLUME:
The tidal volume is the volume of air breathed in and out
during normal quick breathing (about 500ml).Only about 350 ml
of the tidal volume actually reaches the alveoli, the remaining
150 ml remains in the air spaces of nose, pharynx, trachea and
bronchi and is called Dead Air Volume.
2.Minute Volume Of Respiration:
The total air taken in during 1 minute. It is approximately
6000ml per minute.Tidal volume * respiratory rate per minute.

5. 3.Inspiratory Reserve Volume (Irv) :
The air that can be breathed in by maximum inspiratory
effort after an ordinary inspiration. This is approximately 3100ml
above 500 ml of tidal volume thus inspiratory system can fill in
3600 ml of air.
4.Expiratory Reserve Volume:
The air that can be breathed out by maximum expiratory
effort after an ordinary expiration. This is about 1200 ml.
5.Residual volume: the volume of air which remains in the lungs
after maximal expiration. This is about 1200 ml of air.

6. LUNG CAPACITIES
1.Inspiratory capacity:
It is the maximum volume of air that can be inspired the
sum of the tidal volume + inspiratory reserve volume-3600 ml.
2. Vital capacity:
It is the maximal volume of air that can be exhaled after a
maximum inspiration. It is the sum of inspiratory reserve
volume + tidal volume + respiratory reserve volume. It is
approximately equal to 4800 ml.
3. Total lung capacity:
It is the sum of all the lung volumes(6000ml).
Forced vital capacity(FVC):
The maximum volume of air exhaled with maximally
forced effort from a partition of maximal inspiration.

7. LUNG FLOW TESTS BY SPIROMETRY
1.Forced expiratory volume (FEV)
The amount of air measured after force full and completely exhaling
after maximal inspiration.
2.Forced expiratory volume (FEV1)
The measure of forced expiratory volume in the first second of
exhalation is FEV1
FEV1=ratio of FEV1/FEV
3.Peak expiratory flow rate (PEFR)
This is the maximum flow rate achieved by the patient during the
FVC measured from the beginning after full inspiration and ending with
maximum expiration.

8. 4.Forced expiratory flow rate (FEF)
It is the mean forced expiratory flow
during the middle half of the FVC and is measured as
the slope of the line between 25% to 75% of FVC on
the flow volume curve i.e., the FVC curve is divided
into 3 quarters which are FEF 25%, FEF50%,
FEF75% . This measurement describes the amount of
air that was forcibly expelled in the first 25% of FVC
test.
5.Slow vital capacity (svc)
The amount of air that you can slowly exhale
after you inhale as deeply as possible.

10. SPIROMETRY

11. SPIROMETRY
Spirometry is the primary instrument used in the
pulmonary function testing . It is designed to measure
changes in volume and can measure lungs volume
compartments that change gas with atmosphere .
As the patient breaths in and out from the air
enclosed on the surface of water below the bell jar. As
the patient breaths the bell of the spirometer is
displaced and the pen deflection reflects the volume
of air entering and existing the lungs .
The device usually attached to the spirometer
which measures the movement of the gas in and out
of the chest is referred as spirograph .

12. Sometimes the spirograph is replaced by a printer like unit
used in the laboratory. This result tracing is called spirogram.
Pulmonary function test can be grouped into main
categories:
1. Obstructive airway disease
2. Restrictive airway disease
Obstructive airway disease
Obstructive airway disease limits airflow during
expiration . The potency (dilation or openness) is estimated
by measuring the flow of air as the patient exhales as hard as
fast as possible. Flow through the tubular passage ways can
be decreased because of the following :
1. Narrowing of the airways due to bronchial smooth muscle
contraction (asthma).
2. Narrowing of the airways due to inflammation and swelling
of bronchial mucosa as in bronchitis.

13. 3. Material inside the bronchial passageways physically
obstructing the flow of air as in the case of excessive mucous
plugging, inhalation of foreign objects or presence of tumor.
4. Destruction of lungs tissue with loss of elasticity and hence the
loss of external support of airways as in emphysema.
In obstructive lung conditions the airways are narrowed ,
create turbulence and increased resistance to air flow.
RESTRICTIVE AIRFLOW
Restrictive disease limits airflow during inspiration .
This is seen in patients whose total lung capacity is
significantly reduced . Restrictive disease results from loss of
elasticity e.g.. Fibrosis or physical deformities of the chest
with a consequent inability to expand the lungs and reduce
TLC.

14. other varieties of restrictive disorders are:
1. Intrinsic Restrictive Lung Disorder: Tb, pneumonia.
2. Extrinsic Restrictive Lung Disorder: obesity,
pregnancy.
3. Neuromuscular Restrictive Lung Disorder:
Generalized weakness, paralysis of the diaphragm,
myasthenia gravis, muscular dystrophy. In restrictive lung
condition there is the loss of lung tissue , a decreased lungs
ability to expand or decrease in the lungs ability to transfer
oxygen to the blood,

17. FLOW VOLUME CURVES

18. Diffusion capacity test
Tests of gas exchange measure the ability of the
gases to cross (diffuse) the alveolar capillary
membrane and are used in assessing interstitial lung
disease.
Typically these tests measure the per minute
transfer of gas, usually carbon monoxide from the
alveoli to the blood.
The diffusion capacity may be lessened following
losses in the surface area of the alveoli or thickening
of the alveolar capillary membrane. thickening may
be due to fibrotic changes.

19. • These test result can be confounded by a loss of diffusion
capacity due to poor ventilation . The diffusion capacity of the
lungs to carbon monoxide can be measured by either a single
breath or steady state test.
AIRWAY REACTIVITY TEST
Inhaled histamine or Methacholine is used to provoke
bronchospasm in susceptible individuals .
Typical protocols begin by nebulizing low
concentrations of either agent followed by spirometry
(FEV1 OR FVC).

20. • The concentration is doubled at specific time intervals
about 5 minutes until a set decrease usually 20% from
the baseline in the FEV1 or FVC is attained .
• If the maximal concentration of the agent used is less
than or equal to 8 mg/ml, the patient has increased
airway reactivity.
• If the concentration is greater than 8 mg/dl the patient
has normally sensitive airways.

21. THANK YOU