Anti-oxidative therapy protects renal function in cardiac surgery patients

Abstract

Objectives: Oxygen-derived free radical formation induced by cardiopulmonary bypass (CPB) may contribute to renal dysfunction associated with cardiac surgery. As anti-oxidants have been shown to attenuate free radical-induced renal dysfunction in medical patients, we hypothesized that the anti-oxidant N-acetylcysteine (NAC) protects renal function in patients subjected to cardiac surgery on CPB. Material and Methods: Forty coronary artery surgery patients (66±9[SD] years, 9 women and 31 men) with normal preoperative renal function (serum creatinine <0.9mg/dl) subjected to CPB and CA were randomized in a double-blind fashion to receive either NAC (100mg/kg into CPB prime followed by infusion at 20mg/kg/h; n=20) or Placebo (n=20). We measured serum creatinine levels pre- and post-operatively (1. day post CPB) as well as urinary output and diuretic medication. Creatinine clearance was calcuted using the Cockroft equation. Results: In the Placebo group, serum creatinine increased from 93.1±35.4 mmol/l pre-operatively to 115.9±47.2 mmol/l on post-op day 1 (p<.001, 95% CI for mean change: 13.9 to 31.7). In the NAC group, change in serum creatinine was not statistically significant (92.3±31.3 mmol/l pre-operatively; 99.3±25.4 mmol/l on post-op day 1; p=.084, 95% CI for mean change: –0.5 to 14.5). Creatinine clearance decreased significantly in the Placebo group compared to NAC (–16.9±3.2ml/min vs. –7.5±4.2ml/min, p=0.04). Hemodynamics as well as clinical outcome were similar between NAC and Placebo. Conclusions: Our data show that NAC protects renal function post CPB, thus, radical-scavenging may reduce renal dysfunction associated with cardiac surgery.