Study objectives: Cardiopulmonary bypass (CPB) represents a specific risk factor for renal damage during coronary revascularization. The purpose of this study was to compare the perioperative renal damage in patients undergoing on-pump and off-pump coronary surgery.
Design and patients: The progress and extent of renal damage was prospectively studied in two groups of patients undergoing cardiac surgery without concomitant morbidity, undergoing elective coronary revascularization with (n = 12) and without (n = 10) CPB. Markers of glomerular function (creatinine clearance) and damage (microalbuminuria), and markers of tubular function (fractional excretion of sodium [FENa] and free water clearance) and damage (N-acetyl-β-D glucosaminidase [NAG]) were evaluated. Measuring plasma concentrations of free hemoglobin assessed hemolysis. Plasma and urinary specimens were obtained at the following points: (1) baseline; (2) heparinization; (3) the end of CPB or completing graft for off-pump surgery; (4) skin closure; (5) the sixth hour in the ICU; and (6) the second postoperative day. Free water and creatinine clearances, FENa, and the urinary excretion of microalbumin and NAG were calculated for the corresponding time intervals.
Setting: University hospital.
Results: We found that off-pump coronary revascularization induced significantly less changes in microalbuminuria, FENa, free water clearance, NAG, and free hemoglobin as compared with operations with CPB. Markers returned to baseline within 2 days after the operation, and there was no clinical or laboratory evidence of overt renal dysfunction in both groups.
Conclusion: Off-pump coronary surgery attenuates transient renal injury compared with traditional on-pump coronary artery bypass grafting.