The effect of sodium nitroprusside infusion on renal function during reperfusion period in patients undergoing coronary artery bypass grafting: a prospective randomized clinical trial.

Objective: Acute renal failure remains a common and serious complication of cardiac surgery. In this randomized trial, we aimed to assess whether sodium nitroprusside (SNP) infusion during cardiopulmonary bypass (CPB) could prevent renal dysfunction after coronary artery bypass grafting (CABG) surgery.

Methods: Between October 2004 and May 2006, 240 consecutive patients with stable angina undergoing elective CABG for multi-vessel coronary artery disease were prospectively randomized into control (n=116, 72 men, mean age 61.3+/-9.7 years) or SNP groups (n=124, 81 men, 60.8+/-10.8 years). SNP group received SNP after initiation of rewarming period during CPB at a dose of 0.1mg/kg/h and the infusion was concluded by weaning from CPB. The anesthetic and CPB regimes were standardized. Blood urea nitrogen (BUN), serum creatinine (SCr), estimated glomerular filtration rate (eGFR), creatinine clearance (C(Cr)), urine output, serum cardiac specific troponin I (cTnI), creatine kinase cardiac isoenzyme (CKMB), and CPK were measured preoperatively and daily until day 5 after surgery.

Results: There were no differences in baseline levels of BUN, SCr, eGFR, C(Cr), cTnI, CKMB, CPK levels and EuroSCORES between the groups. Although the durations of cross clamp, CPB times, and postoperative cardiac enzymes were similar in both groups; in the control group, there was a significantly lower urine excretion during CPB (p=0.002) and the operation (p=0.041). Peak postoperative SCr levels were significantly (p=0.001) lower in the SNP group than in the control group (1.29+/-0.28 vs 1.42+/-0.34mg/dl). The incidence of >or=50%DeltaSCr was significantly higher in the control group when compared with the SNP group (35.3 vs 13.7%, p<0.001). Development of new C(Cr) less than 50ml/min postoperatively was significantly higher in the control group compared with the SNP group (14 vs 38%, p<0.001).

Conclusion: SNP administration during rewarming period of non-pulsatile CPB in patients undergoing CABG surgery is associated with improved renal function compared with conventional medical treatment providing adequate preload and mean arterial pressures.