SYMPOSIUM: PROFILES OF INTRA-BREATH GAS EXCHANGE DURING EXERCISE1105

Abstract

The rates of pulmonary gas exchange (PGE) during exercise provide important information with respect to tissue bioenergetics, tissue-to-lung transit delays and the dynamics of changes in the body gas stores. Although PGE is typically determined over discrete time intervals, such as each minute of each breath, the exchange is a continuous process and varies within the breath. Analysis of the intra-breath rates of O2 and CO2 exchange provide an additional layer of information regarding both the determinants and efficiency of PGE compared to the more common longest-time averages. This symposium will consider both theoretical and practical aspects of the physiological factors influencing intra-breath PGE during exercise inn health and disease. Special consideration will be given to the physiological inferences which may be drawn from the intra-breath profiles, such as: the amplitude and rate of change of pH in ventilatory control; estimating mean alveolar and arterial PCO2; mixed venous PCO2 and cardiac output; the series dead-space of the lung; and the intra-breath `R' as an index of gas-exchange efficiency.