Values
| Volume | Value (litres) | |
|---|---|---|
| In men | In women | |
| Inspiratory reserve volume | 3.3 | 1.9 |
| Tidal volume | 0.5 | 0.5 |
| Expiratory reserve volume | 1.0 | 0.7 |
| Residual volume | 1.2 | 1.1 |
| Volume | Average value (litres) | Derivation | |
|---|---|---|---|
| In men | In women | ||
| Vital capacity | 4.6 | 3.1 | IRV plus TV plus ERV |
| Inspiratory capacity | 3.8 | 2.4 | IRV plus TV |
| Functional residual capacity | 2.2 | 1.8 | ERV plus RV |
| Total lung capacity | 6.0 | 4.2 | IRV plus TV plus ERV plus RV |
The tidal volume, vital capacity, inspiratory capacity and expiratory reserve volume can be measured directly with a spirometer. These are the basic elements of a ventilatory pulmonary function test.
Determination of the residual volume is more difficult as it is impossible to "completely" breathe out. Therefore measurement of the residual volume has to be done via indirect methods such as radiographic planimetry, body plethysmography, closed circuit dilution (including the helium dilution technique) and nitrogen washout.
In absence of such, estimates of residual volume have been prepared as a proportion of body mass for infants (18.1ml/kg), or as a proportion of vital capacity (0.24 for men and 0.28 for women) or in relation to height and age ((0.0275*AgeInYears+0.0189*HeightInCentimetres-2.6139) litres for normal-weight individuals and (0.0277*AgeInYears+0.0138*HeightInCentimeters-2.3967) litres for overweight individuals). Standard errors in prediction equations for residual volume have been measured at 579ml for men and 355ml for women, while the use of 0.24*FVC gave a standard error of 318ml.
Read more about this topic: Lung Volumes
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