Spirometry

None of the above

The volume of air remaining in the lungs after a maximal effort to exhale all the air possible (ie, after your best effort to “empty” your lungs) is the residual volume. This volume cannot be measured directly by a spirometer, which measures only change in volume. Since you cannot voluntarily change your lung volume below the residual volume, the spirometer cannot measure it. Other methods (eg, body plethysmography, inert gas dilution) must be used to measure residual volume.

The spirometer is a simple device for measuring gas volumes. The frequently used water spirometer, rolling seal spirometer and bellows spirometer. The last two are not water-filled and are more portable.

Residual volume (RV) is the one volume that cannot be measured with a spirometer. The RV cannot be measured with the spirometer because this air cannot be expressed from the lungs. It is measured by indirect methods, such as the helium dilution methods, the nitrogen washout methods, or body plethysmography. Since spirometry cannot measure RV, it is not possible to determine functional residual capacity (FRC) and total lung capacity (TLC) from this test.

• Functional Residual Capacity(FRC) = Residual Volume + Expiratory Reserve Volume.and
• Total Lung Capacity = Insp Reserve Volume + Tidal Volume + Exp Reserve Volume + Residual Volume

Ans:A.)TLC

Spirometry can measure :- Tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), vital capacity (VC), forced vital capacity (FVC), FEVI.

Spirometry cannot measure :- Residual volume (RV), functional residual capacity (FRC), total lung capacity (TLC).

B i.e. Residual Volume

A i.e. FRC

A i.e. Flow rates can be calculated

Ans. is ‘a’ i.e., RV

Spirometry can measure :- Tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), vital capacity (VC), forced vital capacity (FVC), FEVI.

Spirometry cannot measure :- Residual volume (RV), functional residual capacity (FRC), total lung capacity (TLC).