Pulmonary and Vascular Changes Induced by Pressure Breathing
Technical Report,01 Nov 1957,30 Sep 1958
AERONAUTICAL SYSTEMS DIV WRIGHT FIELD OH WRIGHT FIELD
Pagination or Media Count:
This study was performed on six male subjects to determine certain physiological responses induced by positive PPB and negative pressure breathing NPB and to determine if these responses were passively or reflexively induced. Tidal volume increased significantly during both PPB and NPB. During NPB vital capacity was significantly reduced presumably due to engorgement of intrathoracic vasculature. Expiratory reserve volume increased during PPB and decreased during NPB. There was no evidence that these changes were not passive responses. Anatomical dead space increased during both PPB and NPB. Lung compliance decreased significantly during NPB presumably due to pulmonary vascular engorgement. The mechanical work performed on the lung and respired air increased during both PPB and NPB. Although airway resistance during expiration did not change, inspiratory resistance appeared to increase significantly during NPB. Peripheral venous pressure increased during PPB but did not change during NPB. It has no significance during NPB but reflects central venous pressure during PPB. Both responses were passive. Forearm blood flow decreased during PPB and was unchanged during NPB.