| 摘要 |
A method and apparatus for determining a pulmonary function parameter, EVG, indicative of a living subject's effective lung volume, namely the lung volume in which gas exchange between respiratory air and pulmonary blood takes place efficiently. The apparatus carries out the steps of the method: (1) determining for a first breath during normal steady state breathing of the subject the end-tidal carbon dioxide or oxygen concentration Pet1 and the average rate of flow Va1, over the duration T1 of the breath, of expired carbon dioxide or oxygen, (2) determining for a second breath comprising a breath-hold period the end-tidal carbon dioxide or oxygen concentration Pet2 and the average rate of flow Va2, over the duration T2 of the breath, of expired carbon dioxide or oxygen, and (3) determining EVG as a quantity proportional to the ratio of the difference between said average flow rates Va1 and Va2 to the difference between said end-tidal concentrations Pet2 and Pet1. |
