Intrathoracic Volume Changes in Relation to the Cardiopneumogram

Abstract

The outflow of blood from the chest during the phases of the cardiac cycle is found to be nearly equaled by a phasic inflow. The net volume change exerts very small pressure changes in the intrathoracic (intrapulmonary) air. This is not due to the distensibility of the chest wall because when allowance is made for this factor and the intrathoracic blood volume change is calculated, it is found to be a very small fraction of the stroke volume.