A comparison of effects of fixed and tailored cardiopulmonary bypass flowrates on renal function

Cardiopulmonary bypass may result in renal impairment but there is little investigative data on the effect of differing flowrates on postoperative renal function. One hundred and twenty-two patients presenting for cardiac surgery were randomly assigned to receive either a fixed CPB flow of 2.4 l.m-2 or a bypass flow tailored to maintain a venous return oxygen saturation of 75-80%. Vasoactive drugs were given to maintain a perfusion pressure of 50 to 80 mmHg. Patients were assessed by serum creatinine, creatinine clearance, arterial blood gases, serum lactates and electrolytes. The results show an overall decline in postoperative renal function compared with preoperative levels, with no significant differences between the two groups.