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

This study is testing whether giving a medication called N-Acetylcysteine (NAC) before heart surgery can protect the kidneys from damage. People with already-reduced kidney function are at particular risk of their kidneys getting worse during heart surgery. NAC is an antioxidant that may help shield the kidneys from injury during the operation. You may be eligible if: - You are 18 years or older - You have chronic (long-term), stable reduced kidney function - You are scheduled for heart surgery requiring a bypass machine (such as CABG or valve surgery) - You are able to give consent You may NOT be eligible if: - You are a woman of childbearing age who may be pregnant, or you are pregnant or breastfeeding - Your blood pressure is very low before surgery (below 90 mmHg) - You have acute (sudden) kidney failure - You are already on dialysis (haemodialysis or peritoneal dialysis) - You took anti-inflammatory drugs (like ibuprofen) in the last 4 days - You are allergic to acetylcysteine - You have active severe asthma or COPD - You have liver problems - You have had a kidney transplant Talk to your doctor about whether this trial might be right for you.