Effect of positive end-expiratory pressure on ventricular function in dogs

Abstract

Artifical ventilation with positive end-expiratory pressure (PEEP) reduces venous return by raising intrathoracic pressure. To determine whether PEEP decreases cardiac output further by depressing myocardial function, Starling curves were constructed using rapid dextran infusion in 7 anesthetized dogs ventilated with zero (ZEEP) and 20 cm PEEP. The changes in stroke volume and in left ventricular stroke work (LVSW) when PEEP was added or removed were significantly greater than could be attributed to the corresponding change in transmural left ventricular end-diastolic pressure (LVEDPTM) on the Starling curves. To the extent that PEEP did not alter left ventricular diastolic volume-pressure characteristics, the data indicated PEEP depressed ventricular function. Identical changes with PEEP in cardiac output (-30%), esophageal pressure (+10 cmH2O) and left ventricular function were observed after pulmonary edema was induced with oleic acid. Apparently high levels of PEEP depress left ventricular function in dogs, accounting for about 1/2 of the reduction in cardiac output before and during acute pulmonary edema.