Normothermic versus Hypothermic Perfusion During Primary Coronary Artery Bypass Grafting

Abstract

Normothermic versus hypothermic cardiopulmonary bypass was evaluated in 1442 consecutive patients undergoing primary coronary artery bypass grafting (CABG). Group 1 (n = 545) were operated on in moderate systemic hypothermia (rectal temperature 28°C) and group 2 (n = 897) in normothermia (rectal temperature 37°C). Both groups had cold cardioplegic arrest (10°C) and local cooling of the heart with slush. Anaesthesia and operative techniques were identical in both groups. The mean age was 60 years; group 2 contained significantly more patients aged >65 years (P< 0.05) and had more frequent emergency operations (P< 0.001) than group 1. Other preoperative patient characteristics were similar between groups. Aortic cross-clamping time was similar in both groups but cardiopulmonary bypass time was significantly longer in group 1 than in group 2 (97.9(28.8) versus 76.6(26.0) min, P< 0.001). Perioperative mortality rate was 3.3% in group 1 and 2.6% in group 2. The incidence of myocardial infarction was significantly higher in group 1 than in group 2 (2.0% versus 0.7%) Perioperative low cardiac output needing inotropic support was similar in both groups, but group 1 patients required more intra-aortic balloon insertions (4.6% versus 2.2%, P< 0.05). Lower incidence of postoperative ventricular arrhythmias, shorter intubation time and less transient renal failures were significant in group 2 compared with those in group 1 (P< 0.001), while re-exploration of bleeding, wound infections, pulmonary, neurological and gastrointestinal complications did not differ. Blood transfusion was less in group 2 (1.2(1.1) units, P< 0.001). On day 1 after surgery, serum creatinine, lactate dehydrogenase and creatine Phosphokinase values were increased in both groups but were significantly lower in group 2 (P< 0.001). Normothermic cardiopulmonary bypass combined with cold cardioplegic arrest is safe and provides sufficient cardiac and total body protection during primary CABG. Several of the adverse effects of hypothermia can be avoided, such as prolonged cardiopulmonary bypass time and ventilatory support, disturbed haemostasis and transient renal failure.