THE EFFECTS OF POSITIVE END-EXPIRATORY PRESSURE ON RIGHT AND LEFT-VENTRICULAR PERFORMANCE

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Abstract
The cardiovascular effects of positive end-expiratory pressure (PEEP) were studied in mechanically ventilated, vagotomized, .beta.-blocked, anesthetized dogs. To compensate for the effect of PEEP on decreasing systemic venous return, acute plasma volume expansion was accomplished returning stroke volume and cardiac output to control values. Left and right ventricular filling pressures (LVFP and RVFP) and aortic pressure were measured relative to pleural pressure (transmural pressure). Ventricular performance was assessed by comparing the transmural ventricular filling pressures at similar stroke volumes. Studies were performed on individual dogs with increasing LVFP produced by .beta.-blockade, volume expansion and obstruction of the descending thoracic aorta. For a given cardiac output, transmural LVFP was higher on PEEP compared to a control state with normal and elevated control LVFP. On the right side, for a given cardiac output, RVFP was elevated only when control LVFP was elevated. Apparently there is a nonneuronal adverse effect of PEEP on left and right ventricular performance. This effect is probably due to mechanical heart-lung interaction since left ventricular (LV) dp/dt [contractility] showed no change.