THE EFFECTS OF THE TRACHEAL PRESSURE UPON FLOW: PRESSURE RELATIONS IN THE VASCULAR BED OF ISOLATED LUNGS

Abstract

In isolated cats' lungs, perfused at steady inflows with a mixture of plasma and dextran, we measured the pulmonary arterial pressure, the left atrial pressure, the tracheal pressure and the inflow of perfusate. We were able to obtain directly or to calculate relations between any pair of these four variables with the remaining pair at constant values. The results are used to analyze how tracheal pressures affect the pulmonary vascular bed and to consider some consequences of the changes in pressure which occur during cardiac and respiratory cycles in the whole animal.