Effect of continuous positive airway pressure applied by face mask on right ventricular function after cardiac...

The effect of respiratory therapy with continuous positive airway pressure (CPAP) on right ventricular function 24 hours after elective cardiac surgery was evaluated in patients with or without severe coronary artery disease. The first group included 10 patients following coronary artery bypass graft (CABG) surgery, and the second group included 10 patients following aortic valve replacement (AVR) without preexisting coronary artery disease. Patients of both groups had preoperative left ventricular ejection fractions above 40%. CPAP was applied by face mask at a flow rate of 20 L/min with 40% oxygen in nitrogen and with a positive end-expiratory pressure of 12 cmH2O. Right ventricular function was estimated at end-expiration by a fast-response thermodilution cardiac output catheter. The results demonstrate that in both groups of patients, CPAP did not significantly modify right ventricular indices, ejection fraction, end-systolic and end-diastolic volume indices, and stroke volume index, indicating that CPAP can safely be applied after elective cardiac surgery in patients with or without severe coronary artery disease and preoperative left ventricular ejection fractions above 40%. Furthermore, the concomitant postoperative intravenous infusion of nitroglycerin (to all 10 patients of the CABG group and to 4 patients of the AVR group) counteracted the expected beneficial effect of CPAP therapy on arterial oxygenation.