Pulmonary Blood Flow and Venous Return During Spontaneous Respiration

Abstract

During normal spontaneous inspiration pulmonary blood flow increases in spite of an increase in resistance to flow in the pulmonary bed. The enhancement of pulmonary flow is caused by an augmentation of venous return due to thoracic aspiration. The right heart acts as a moderator for the pulmonary flow by temporarily storing part of the large influx of venous blood during inspiration and ejecting the stored part during expiration and the expiratory pause.