This document discusses lung volumes and capacities, including tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume, vital capacity, inspiratory capacity, functional residual capacity, and total lung capacity. It defines each term and provides normal values. Spirometry and helium dilution techniques are used to measure the various lung volumes and capacities, which can help diagnose lung diseases.

1. Lung volumes

2. Objectives
To know about different lung volumes and
capacities
To know how to measure them
And their significance in diagnosing lung
diseases

3. 4 volumes and 4 capacities
Tidal volume
Inspiratory
reserve volume
Expiratory
reserve volume
Residual volume
Vital capacity
Inspiration
capacity
Functional
residual capacity
Total lung
capacity

4. THESE ARE MEASURED USING A TECHNIQUE CALLED
SPIROMETRY
INDIRECT SPIROMETRY USING HELIUM DILUTION
TECHNIQUE IS USED TO MEASURE FRC THOUGH WHICH
RV AND TLC ARE DERIVED
DIRECT SPIROMETRY CAN MEASURE ALL THE
REMAINING LUNG VOLUMES AND USED TO DERIVE
OTHER LUNG CAPACITIES

5. Tidal volume
“The tidal volume (TV) is the volume of air that is drawn into
the lungs during inspiration from the end-expiratory position
(and also leaves the lungs passively during expiration) in the
course of quiet breathing.”
Normal value = 6-8 ml/kg

6. Inspiratory reserve volume
The maximum amount of air that can be
inhaled after a normal tidal volume
inspiration
Normal value 1900-3300ml

7. Expiratory reserve volume
“The expiratory reserve volume (ERV) is the maximum
volume of air that can be forcibly exhaled after a quiet
expiration has “been completed (i.e., from the end-
expiratory position).”
Normal value is 700 -1000 ml

8. Residual volume
“The residual volume (RV) is the volume of air that
remains in the lungs after a maximal expiratory effort.
Set by balance b/w actions of expiratory muscle & recoil
forces of lung which act to decrease lung volume & outward
recoil forces of chest wall devouring lung expansion
Normal value is

9. Vital capacity
Volume of air that can be exhaled from lungs after maximum inspiration
Vital capacity =IRV + TV + ERV
Normal value is 60-70ml /kg

10. Inspiratory capacity
Maximum amount of air that can be
inhaled from end of tidal volume i.e from
a normal expiratory position
 INSPIRATORY CAPACITY= IRV + TV

11. Functional residual capacity
“The functional residual capacity (FRC) is the volume of air
that remains in the lungs at the end of a normal
expiration.”
FRC = ERV+ RV

12. Total lung capacity
“The total lung capacity (TLC) is the total volume of air contained in the lungs a
the end of a maximum inspiration.”
TOTAL LUNG CAPACITY = IRV + TV + ERV + RV
 It “is determined by the balance between the force-generating capacity of the inspiratory muscles and the
opposing elastic recoil forces of the lung and chest wall.
 Weakness of the muscles of inspiration or increased stiffness of the lung reduces TLC.
 Loss of retractive forces exerted by the lung, as in emphysema, enlarges TLC.”

13. Normal values at a glance (for a 20yr old healthy
seated make)
 Tidal volume=0.6L
 Residual volume=1.4L
 E.R.V= 1.9L
 I.R.V= 3.0L
I.C=3.0L
F.R.C=3.2L
T.L.C= 6.3 L
V.C= 4.8 L

15. Thank you