Preoperative intranenous N-Acetylcysteine for the prevention of renal failure in patients with renal impairment undergoing cardiac surgery

INTERVENTION: Patients who fit into Inclusion criteria will be randomised to receive intravenous N‐Acetylcestine 150mg/kg for 16 hours. CONDITION: Renal Impairment in cardiac surgery PRIMARY OUTCOME: Occurrence of acute renal failure as defined by an increase in serum creatinine of greater than or equal to 44umol/L over the baseline value or an increase in creatinine of greater than 50% above baseline or a reduction in calculated creatinine clearance of 50%. SECONDARY OUTCOME: Creatinine clearance Cystatin C levels In hospital mortality rate. Length of ICU stay Length of hospital stay Peak serum creatinine level Requirement for dialysis in hospital INCLUSION CRITERIA: 1. Patients with chronic stable renal impairment as evidenced by a creatinine >133µmol//L or creatinine clearance < 50ml/min as estimated by the Cockcroft‐ Gault formula20. ( Creatinine clearance or CrCl will be calculated by applying the Cockcroft‐ Gault formula to the baseline serum creatinine level: (140 – age) x weight/ serum creatinine x 0.815; with a female adjustment: CrCl female = CrCl x 0.85)2. Patients undergoing cardiac surgery requiring cardiopulmonary bypass including but not exclusive to coronary artery bypass grafting (CABG), valve surgery, combination CABG and valve replacement procedures, adult patients undergoing surgery for congenital heart disease, repairs of ventricular aneurysm, septal defect repairs and removal of myxomas, stable patients with intraaortic balloon pump (IABP) inserted electively preoperatively, redo cases requiring cardiopulmonary bypass (CPB). 3. Patients who have given consent.