This document discusses lung volumes and lung capacities, which refer to the volume of air associated with different phases of the respiratory cycle. It outlines the four main lung volumes - tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. It then discusses various lung capacities, which are combinations of two or more lung volumes, including inspiratory capacity, expiratory capacity, functional residual capacity, vital capacity, and total lung capacity. The document provides normal values for males and females for these volumes and capacities.

2.  Lung volumes and lung capacities refer
to the volume of air associated with
different phases of the respiratory cycle.
 Lung volumes are directly measured;
Lung capacities are inferred from lung
volumes
 Instrument is spirometry

3.  Four types
1. Tidal volume
2. Inspiratory reserve volume
3. Expiratory persevere volume
4. Residual volume

4.  Normal volume of air inspired or expired
during quiet breathing
 TV = 500 ml

6.  Extra volume of air inhaled after tidal
volume by max inspiratory effort
 3000ml in adult male
(or)
 3300 / 1900 = M/F

7.  Extra volume of air that can be exhaled
after tidal volume by max expiratory
efforts
 1100 in a normal adult male
(or)
 1200/700 = M/F

8.  Volume of the air left out in lungs after
forceful expiration or complete
expiration
 1200/1100 = M/F

10.  These are combinations of two or more
lung volumes
1. Inspiratory capacity
2. Expiratory capacity
3. Functional residual capacity
4. Vital capacity
5. Total lung capacity

11.  Max volume of air that can be inspired
after normal tidal expiration
 IC = TV+IRV
= 500 +3000
= 3500 ml

12.  Max volume of air that can be expired
after normal tidal inspiration
 EC=TV+ERV (500+1100=1600ml)

13.  Volume of air remaining in lungs after
normal tidal expiration
 FRC= ERV + RV ( 1100 + 1200 = 2300ml)

14.  Significance ?
› Continues exchange of gases
› So that conc of O2 and CO2 is maintained
› Breath holding is made possible
› Dilution of toxic inhaled gases
› Prevents colapse of lungs
› reduces workload of respiratory muscles
and rt ventrcle

15.  Old age
 Obstructive and restrictive lung diseases

16.  Max Amount of air expelled after
deepest possible inspiration
 VC = TV+IRV+ERV
 500+3000+1100= 4600ml

17.  To asses strength of respiratory muscles
 Factors affecting VC
› Age
› Sex
› Strength of respiratory muscles
› Gravity
› Pregnancy
› Ascites
› Pulmonary diseases

18.  Volume of air present in lung after max
inspiration
 TLC = VC + RV ( 4600+1200 = 5800ml )

21.  Timed vital capacity or FVC
 FVC is volume of the air that can be
expired rapidly with max force following
a max inspiration , and its timed by a
spirograph

22.  FEV1 – volume of air expired in the first
second of FVC
 Fev1 is flow rate
 Fev1 is expressed in percentage
 Fev1 = 80%
 Fev2 = 90 %
 Fev3 = 98-100 %


23. 0 1 2 3
5000
4000
3000
2000
1000
0
Time (sec)
Volume(ml)
FEV1 = (5000 ml -1000 ml) / 5000ml
= 4000 ml / 5000 ml
= 80%

24.  Low in obstructive lung diseases
 Normal or high in restrictive lung diseases

25.  It’s the mean expiratory flow rate during
the middle 50% of FVC
 Normal is 300L/min in 0.5 sec

27.  Aka pulmonary ventilation
 Volume of air inspired or expired per
minute
 RMV = TV * RR ( 500* 12 = 6000 ml)
 6 – 7.5 L/min

28.  Aka MVV
 Max volume of air that can be ventilated
voluntarily for given interval of time
 Subject asked to breath rapidly and deeply
, for 15 seconds
 Recorded by a spirometer or Douglas bag
 Normal is 80- 170 L/min
 Reduced in pt with emphysema and
respiratory muscle weakness

29.  Maximum amount of air above the PV
that can be inspired or expired in one
min
 PR = MVV – PV
 Pulmonary reserve is expressed as % of
MVV and is known as dyspnoeic index

30.  Normal DI is 60 – 90%
 Average of 75%
 Importance is dyspnoeia results when DI
becomes less than 60%