MYOCARDIAL DEPRESSANT EFFECT OF NITROUS OXIDE AFTER CORONARY ARTERY BYPASS GRAFT SURGERY

We have studied the cardiovascular effects of nitrous oxide after cardiac ischaemia-reperfusion injury caused by aortic cross-clamping and unclamping during coronary artery bypass grafting (CABG). At the time of chest closure. 20 patients were allocated randomly to receive oxygen and air (Flo<inf>2</inf> = 0.5) or 50% nitrous oxide in oxygen in addition to anaesthesia with fentanyl. Nitrous oxide significantly decreased mean arterial pressure (P < 0.01) and cardiac index (P < 0.05), which suggests that nitrous oxide with fentanyl may significantly depress left ventricular performance after CABG. Although ischaemia-reperfusion cardiac injury did not appear to increase the myocardial depressant effect of nitrous oxide, the use of nitrous oxide is not recommended immediately after CABG.