Gas Stores of the Body and the Unsteady State

Abstract

In order to predict changes in respiratory gas exchange during the unsteady state it becomes necessary to know how ventilation and cardiac output control O2 and CO2 stores of the body. Changes in body CO2 stores were obtained experimentally in dogs and are 1.5 cc/kg/mm CO2 change. Of this 1.02 cc comes from the tissues to the exclusion of blood. Readjustments of the O2 stores are faster than that for the CO2 stores. With changes in alveolar ventilation these readjustments proceed at an exponential fashion, 50% change being obtained in .5 minute for O2 stores and 4 minutes, for CO2 stores. From these data overall changes in body stores between different steady states can be calculated as well as their effect on the respiratory gas exchange during the unsteady state. The influence of stores readjustment on respiratory gas exchange ratio was determined during changes in ventilation or in cardiac output. A model based on the experimental data can be constructed and allows visualization of the integrated mechanism of gas transport as well as the different factors which influence gas transport and storage.