Changes of right ventricular function with positive end-expiratory pressure (PEEP) in man.

The side effects of positive pressure ventilation on cardiovascular function are well known. However, in most clinical studies its influence on left ventricular function was examined. In the present study right ventricular (RV) performance was studied in 13 patients undergoing coronary artery bypass grafting during mechanical ventilation with and without positive end-expiratory pressure (PEEP). In the majority of patients (10/13), PEEP caused a decrease in RV end-diastolic volume (by 18%) whereas RV ejection fraction did not change. In the remaining 3 patients, end-diastolic and end-systolic RV volumes increased by 25% and 50% respectively and ejection fraction decreased by 29%. These results suggest that PEEP can affect RV function in two different ways: first, in the majority of patients studied, PEEP exerted an unloading effect on the RV whereas second, in 3 patients RV dilatation and a decrease in ejection fraction was observed.