Renal function after cardiopulmonary bypass surgery in patients with impaired renal function. A randomized study of...

Postoperative acute renal failure predicts morbidity and mortality. We investigated the effect of nifedipine infusion on glomerular filtration rate in patients with impaired renal function undergoing cardiopulmonary bypass surgery.

Twenty patients accepted for coronary bypass and/or heart valve surgery were enrolled prospectively and randomized to nifedipine infusion or no treatment. Males and females with creatinine 150 micromol L(-1) and 130 micromol L(-1), respectively, were included. Patients with unstable angina pectoris, ejection fraction 35% and those on dialysis were excluded. Glomerular filtration rate was measured preoperatively and 48 h postoperatively. Creatinine clearance was measured preoperatively and 0-4, 20-24 and 44-48 h postoperatively. There were no statistically significant differences in patient characteristics. Biochemical markers in plasma and urine were measured before and 48 h after surgery.

The mean +/- SD preoperative glomerular filtration rates were 32.2 +/- 11.5 and 31.4 +/- 17.0 mL min-1 per 1.73 m2 in the nifedipine and control groups (P = 0.90), respectively. There was no statistically significant change in the glomerular filtration rate or in creatinine clearance over time within or between groups. A linear mixed model showed no effect of nifedipine (P = 0.44), time (P = 0.97) or interaction of nifedipine and time (P = 0.99) on creatinine clearance. Perioperative arterial pressure was kept within predefined targets. Three patients received dialysis postoperatively, all in the control group (P = 0.21). There were no statistically significant differences between groups in changes of urinary or plasma biochemistry.

Renal function was well preserved after cardiopulmonary bypass surgery in patients with impaired renal function when maintaining thorough intensive care surveillance. Nifedipine did not influence early postoperative renal function.