Objectives: Determination of the rate of acute kidney injury incidence, following fluid resuscitation with isotonic saline compared to Ringer lactate in patients undergoing off-pump coronary bypass, hospitalized in the intensive care unit (ICU). Design: Randomized clinical trial, single blind, Target sample size: 966 people. Inclusion criterion to study: patients after undergoing elective off-pump coronary bypass. Exclusion criteria from study: Emergency surgical operation; Previous history of cardiac surgery; American Society of Anesthesiologists Class ( ASA) more than 4; Previous history of kidney diseases; Diabetic nephropathy; Preoperative serum creatinine level more than 1.3; Preoperative glomerular filtration rate (GFR) less than 75%, 8) preoperative ejection fraction (EF) less than 30%; Drainage more than the volume during the surgery; Use of a balloon pump during or after the surgery; Prolonged recurrent ventricular fibrillation (VF) during the surgery; High dose inotrope (inotrope 2) during the surgery; Lack of patient’s consent to participate in the study. Patients are also excluded during the study period if hyperchloremia (CL more than 110) occurs in the ICU, Various complications might occur (hemorrhage, drainage, cardiac arrest, prolonged hemodynamic instability, and neurological complications of CVA), which result in the exclusion of patients from the study.
Control group: Isotonic saline 0.9% containing 154 mEq chlorine ion, 40 CC/kg at 24 hours after surgery Intervention group: Ringer lactate containing 109 mEq chlorine ion, 40 CC/kg at 24 hours after surgery. Primary outcome: Arterial blood gases, Before and at the first 24 hours after intervention, every 4 hours, By Blood test; Blood urea nitrogen, Before and after intervention, daily by blood test, venous blood samples from the arm; Blood creatinine level, daily by blood test in jaffe method.