OSMANIA MEDICAL COLLEGE, UPGRADED DEPARTMENT OF PHYSIOLOGY
PRACTICAL DEMONSTRATION OF SPIROMETRY
Aim: To record Vital Capacity and Calculate Vital Index in the given subject
Apparatus: Student Spirometer, Potassium Permanganate solution, Stadometer,
Weighing machine
Procedure:
Standard Method:
Bring the bell to it’s lowest position
Adjust the pointer needle at zero
Ask the subject to stand comfortably facing the spirometer
Tell the subject to breathe normally for a minute
Instruct the subject to inspire as deeply and as fully as possible
Instruct the subject to keep nostrils closed and hold the mouthpiece of
the Spirometer firmly between the lips
While keeping the nostrils closed, instruct the subject to expel all the air
with maximum effort into the Spirometer
At intervals of 5 minutes, take 2 more readings
Record the observations in a tabular form
The maximum of the 3 readings is taken as Vital Capacity
Measurement of Vital capacity from the full spirometer:
Raise and lower the bell a few times
Finally raise the bell to it’s highest position so that it gets filled with
room air
Note the reading
Tell the subject to breathe deeply a few times
Instruct the subject to expel air from the lungs with maximum effort
Instruct the subject to keep nostrils closed and hold the mouthpiece of
the Spirometer firmly between the lips
While keeping the nostrils closed, Instruct the subject to breathe in
maximally from the Spirometer
Note the reading
The difference between the two readings is taken as Vital Capacity
Two stage Vital Capacity determination:
Stage I (Measurement of Inspiratory Capacity)
Fill the Spirometer with fresh room air
Note the reading
Ask the subject to breathe normally a few times
Starting from end-expiratory position, Instruct the subject to inspire
maximally from the Spirometer
Note the reading
The difference between the two readings is noted as Inspiratory
Capacity
Stage II (Measurement of Expiratory Reserve Volume)
Bring the bell to it’s lowest position
Ask the subject to breathe normally a few times
Starting from end-expiratory position, Instruct the subject to expel all
the air from the lungs with maximum effort into the Spirometer
Note the reading as Expiratory Reserve Volume
The sum of Inspiratory Capacity and Expiratory Reserve Volume is
Vital Capacity
Effect of Posture on Vital Capacity
Record Vital Capacity in Standing, Sitting & Supine postures
Take 3 readings in each posture
Keep an interval of 2 minutes between changing of postures
Vital Index
Record Height and Weight
Calculate Body Surface Area using Du Bois Nomogram
Calculate Vital Index = Vital Capacity / Body Surface Area
Observation:
S.No Posture Vital Capacity (readings) Maximum of 3
(mL) readings (mL)
1 Standing 1st reading
2nd reading
3rd reading
2 Sitting 1st reading
2nd reading
3rd reading
3 Supine 1st reading
2nd reading
3rd reading
Body weight (kg) =
Height (m) =
Body surface area =
Vital Index =
