Prolonged measurement of respiratory tidal and minute volumes.

A method is described by which successive expiratory tidal and minute volumes are measured by a flow-resistance device (pneumotachometer) which is automatically calibrated up to three times per minute by intermittent collection of gas in a spirometer. Records of any duration, at rest or during exercise, can be made without interruption. The method automatically corrects for the composition of gas flowing through the pneumotachometer, and is suitable for minute-to-minute or breath-by-breath studies of gas exchange or respiratory timing.