Patent ID: 6302851
Filing Date: 2001-10-16
Classification: A61B

Abstract:
A method 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, comprising the steps ofdetermining for a first breath during normal steady state breathing of the subject the end-tidal concentration P.sub.et1 of a given component of the respiratory air, said given component being one of carbon dioxide and oxygen, and the average rate of flow V.sub.a1, over the duration T.sub.1 of the breath, of the quantity of said given component expired during the breath,determining for a second breath comprising a breath-hold period the end-tidal concentration P.sub.et2 of said given component and the average rate of flow V.sub.a2, over the duration T.sub.2 of the breath, of the quantity of said given component expired during the breath,determining EVG as a quantity proportional to the ratio of the difference between said average flow rates V.sub.a1 and V.sub.a2 of said given component to the difference between said end-tidal concentrations P.sub.et2 and P.sub.et1 of said given component.