The document outlines lung volumes and capacities, differentiating between measured volumes and inferred capacities. It details the types of lung volumes—such as tidal volume and residual volume—as well as various lung capacities including inspiratory and vital capacity, and describes the spirometry method used to measure these parameters. Important metrics like forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) are explained in the context of assessing respiratory health.

1. LUNG VOLUME AND
CAPACITIES

2.  Introduction
 Lung volumes
 Lung Capacities
 Measurement of lung volume and capacities
Outline

3.  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
Introduction

4.  Four types
1. Tidal volume
2. Inspiratory reserve volume
3. Expiratory persevere volume
4. Residual volume
Lung Volumes

5.  Volume of air inspired or expired in a single
quiet respiration.
 TV = 500 ml
Tidal volume

7.  It is an additional volume of air that can be
inspired forcefully after end of normal
inspiration.
 Normal volume : 3-3.5L
Inspiratory reserve volume

8.  It is an additional volume of air that can be
expired out forcefully after a normal expiration.
 Normal Value: 1.5L
Expiratory Reserve Volume

9.  It is the volume of air remaining in the lungs
after a maximal expiration.
 Normal values – 1- 1.5L
Residual Volume

11.  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
Lung capacities

12.  It is the maximum volume of air that is inspired
after normal expiration.
 IC = TV+IRV
3.5- 4 L
Inspiratory capacity

13.  Max volume of air that can be expired after
normal tidal inspiration
 EC=TV+ERV
 2L
Expiratory Capacity

14.  It is the maximum volume of air that can be
expired after a maximal inspiration.
 VC= IRV + TV + ERV
 4.5-5L
Vital Capacity

15.  It is the Volume of air remaining in lungs after
normal tidal expiration
 FRC= ERV + RV
 2.5-3 L
Functional Residual Capacity

16.  It is the volume of air present in lungs after a
deep ( maximal) inspiration.
 TLC= IRV + TV + ERV + RV
 VC + RV
 6-6.5L
Total Lung Capacity

19.  Spirometery is the method to measure lung
volumes and capacities.
 Simple instrument used for this purpose is
called Spirometer.
 It is the most readily available pulmonary
function test.
 It measures the volume of air exhaled at
specific time points during a forceful and
complete exhalation after a maximal inhalation.
Spirometery

20.  The forced vital capacity (FVC) (also known as
the forced expiratory volume) is the maximal
volume of air exhaled with a maximally forced
effort from a position of full inspiration and is
expressed in liters.
 The highest FVC from the three acceptable
forced expiratory maneuvers is used for
interpretation

21.  The FVC may be reduced by suboptimal patient
effort, airflow limitation, restriction (eg, from
lung parenchymal, pleural, or thoracic cage
disease), or a combination of these

22.  The slow vital capacity (SVC) is the maximal
volume of air exhaled after a maximal
inspiration, but without a forced effort.
 For normal subjects, the slow and forced vital
capacities are very close, whereas patients with
airflow limitation tend to have a lower FVC than
SVC

23.  The forced expiratory volume in one second
(FEV1) is the maximal volume of air exhaled in
the first second of a forced exhalation that
follows a full inspiration, expressed in liters.
 The highest FEV1 from the three acceptable
forced expiratory maneuvers is used for
interpretation

24.  The FEV1/FVC ratio is the fraction of the forced
vital capacity that can be exhaled in the first
second. It is the most important parameter for
detecting airflow obstruction in diseases like
asthma and COPD

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