Alveolar Air,Respiratory Dead Space,and the “Ventilation Index.”

Abstract

Summary

The ventilatory response of 9 normal persons to muscular exercise can be described in part by a linear relationship between tidal volume and carbon dioxide output per breath. The intercept (Fig. 1) is the effective respiratory dead space and the slope is the reciprocal of the effective alveolar carbon dioxide partial pressure. Thus, during exercise and recovery, involving large changes in oxygen consumption and tidal volume, both effective respiratory dead space and effective alveolar carbon dioxide remain remarkably constant. This circumstance makes possible the calculation of dead space and alveolar partial pressures without recourse to direct sampling methods.