Pulmonary vascular resistance as determined by lung inflation and vascular pressures

Abstract

A controlled study of the effects of pulmonary arterial, left auricular, pleural and intrapulmonary pressures on pulmonary vascular resistance in live dogs was carried out. More than 350 pressure-flow curves were obtained from 10 dogs, using a vertical tube apparatus for perfusion of the left lung with the dog's own blood. The data obtained permit quantitation of the changes in resistance resulting from changes in each of the four pressure parameters. In general, pulmonary vascular resistance fell in response to elevation of either pulmonary arterial or left auricular pressures. Positive pressure inflation invariably produced a considerable rise in resistance, but negative pressure inflation resulted in only a slight fall, followed by a small resistance rise on further inflation. A quantitative integration of the data was made to analyze the effects on pulmonary vascular resistance of spontaneous breathing and positive-pressure inflation with the chest closed. This shows, for example, that the net effect on resistance of even a deep spontaneous inspiration would be small, yet flow would increase considerably. Submitted on March 7, 1960