1. Lung Volumes and Capacities
Dr ibraheem Bashayreh

2. Lung Volumes and Capacities
The total volume contained in the lung at the end of a maximal inspiration is subdivided into volumes and subdivided into capacities.

3. There are 4 volume subdivisions
They do not overlap
They can not be further divided
When added together equal total lung capacity

4. Lung Capacities
Are subdivisions of the total volume that include two or more of the 4 basic lung volumes

5. Basic Lung Volumes Tidal Volume: TV
The amount of gas inspired or expired with each normal breath.
About 500 ml

6. Basic Lung Volumes Inspiratory Reserve Volume: IRV
Maximum amount of additional air that can be inspired from the end of a normal inspiration.

7. Basic Lung Volumes Expiratory Reserve Volume: ERV
The maximum volume of additional air that can be expired from the end of a normal expiration.

8. Basic Lung Volumes nitrogen helium
Residual Volume: RV
The volume of air remaining in the lung after a maximal expiration. This is the only lung volume which cannot be measured with a spirometer.
Gas dilution tech
nitrogen
helium
Body Plethysmograph

9. Lung Capacities Total Lung Capacity: TLC
The volume of air contained in the lungs at the end of a maximal inspiration.
Called a capacity because it is the sum of the 4 basic lung volumes
TLC= RV+IRV+TV+ERV

10. Lung Capacities Vital Capacity: VC
The maximum volume of air that can be forcefully expelled from the lungs following a maximal inspiration.
Called a capacity because it is the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume.
VC= IRV+TV+ERV = TLC - RV

11. Lung Capacities
Functional Residual Capacity: FRC
The volume of air remaining in the lung at the end of a normal expiration.
Called a capacity because it equal residual volume plus expiratory reserve volume.
FRC= RV+ERV

12. Lung Capacities Inspiratory Capacity: IC
Maximum volume of air that can be inspired from end expiratory position.
Called a capacity because it is the sum of tidal volume and inspiratory reserve volume.
This capacity is of less clinical significance than the other three.
IC= TV+IRV

13. Respiratory Diseases Restrictive Disease:
Makes it more difficult to get air in to the lungs.
They “restrict” inspiration.
Decreased VC; Decreased TLC, RV, FRC
Includes:
Fibrosis
Sarcoidosis
Muscular diseases
Chest wall deformities

14. Respiratory Diseases Emphysema Chronic bronchitis Asthma
Obstructive Disease
Make it more difficult to get air out of the lungs.
Decrease VC; Increased TLC, RV, and FRC
Includes:
Emphysema
Chronic bronchitis
Asthma