CLOSING VOLUMES WITH VARIATIONS IN PULMONARY CAPILLARY WEDGE PRESSURE

Abstract

Increased closing volumes occur in patients in whom there was suspected to be early pulmonary edema due to increased pulmonary capillary wedge pressure. The relationship between the actual pulmonary capillary wedge pressure and closing volume is not established. To define this relationship and to determine whether the closing volume might be a useful indicator of the onset of pulmonary edema, closing volume was measured in dogs while sequentially increasing pulmonary capillary wedge pressure by way of a left atrial balloon. There was a small but significant increase in closing volume (P < 0.01) when a pulmonary capillary wedge pressure of 25 mm Hg was achieved; at this pressure pulmonary edema would hypothetically be expected to begin.