A prospective and randomized study has been carried out. The study was approved by the “Medicana International Ankara Hospital Ethics Committee” and written informed consent was taken from every patient. The only inclusion criteria were isolated on-pump CABG procedure. Both genders were accepted. There were no age or weight restrictions. Exclusion criteria were; repeat cardiac surgery, emergent surgery, preoperative coagulation disorder, preoperative clopidogrel use, preoperative congestive heart failure, preoperative renal dysfunction (serum creatinine > 1.3 mg/dl), preoperative hepatic dysfunction (serum aspartate/alanine amino transferase > 40U/l), preoperative electrolyte imbalance, history of pancreatitis and known hypersensitivity to HES. Between October 2011 and April 2012, after the inclusion and exclusion criteria were employed 200 isolated CABG cases were studied. The patients were then randomized as follows: each patient was given a number according to chronological order beginning from 1. The odd numbered patients (n:100) were administered 6% HES 130/0.4 in 0.9% sodium chloride (Voluven® %, Fresenius Kabi, Bad Homburg, Germany) as CPB prime solution and even numbered patients (n:100) were administered a balanced multielectrolyte solution (Isolyte-M®, Eczacıbaşı-Baxter, İstanbul: dextrose monohydrate, 40 mEq/l sodium, 40 mEq/l chloride, 35 mEq/l potassium, 15 mEq/l phosphate, 20 mEq/l acetate; 400 mOsm/l, 170 kCal/l).
Preoperative acetylsalicylic acid 100 mg/day was continued in all patients prior to the day of surgery. All patients were premedicated with 10 mg of oral diazepam. Anesthesia was induced with etomidate 2 mg/kg, fentanyl 1 μg/kg, vecuronium 1 mg/kg; isofluorane 1 MAC was used for anesthesia maintenance. Intraoperative arterial and central venous pressure monitorization were done.
The cardiopulmonary bypass (CPB) circuit was primed with 1,500 ml of determined solution. In both groups 5,000 units of heparin was added. After anticoagulation with heparin (300 U/kg), activated clotting time (ACT) was kept over 400 seconds. CPB was established using a roller pump with a membrane oxygenator (Dideco Compactflo Evo, Sorin Group, Mirandola Modena, Italy). The average flow rate varied from 2.3 to 2.4 l/min/m2. Surgery was performed under mild hypothermia (33°C). Mean arterial pressure was kept between 45 to 70 mm Hg. All patients were rewarmed to 37°C (nasopharyngeal temperature) before weaning from CPB. Heparin was neutralized with 1:1 protamine sulfate.
Cold (4-8°C) blood cardioplegia of 1000 ml (25 mEq/l potassium) was administered after aortic cross clamping, and 500 ml repeat doses were given every 15 to 20 minutes (antegrade and from venous bypass grafts, retrograde in patients with left main coronary disease). Terminal warm blood cardioplegia (36-37°C) was given prior to aortic clamp release.
The operation room temperature was kept at 20-21°C.
In postoperative period rate of fluid infusions were adjusted according to hemodynamic measurements. Central venous pressure was maintained between 8–12 mm Hg.
Packed red blood cell was given if the hematocrit level fell below 25%. Fresh frozen plasma and platelet concentrates were administered in cases of documented postoperative coagulation abnormalities (international normalized ratio > 1.5, activated partial thromboplastin time > 60 s and platelet count < 80,000/mm3) or suspected postoperative platelet dysfunction and factor deficiency.
The decision for re-exploration for hemorrhage was made when 200 ml/hour of drainage was documented on two consecutive hours despite measures taken or more than 300 ml/hour drainage.
On postoperative day 1, all patients were administered metoprolol (50 mg/day) or carvedilol (3.125-6.25 mg/day) and N-acetylcysteine (oral: creatinine < 1.3 mg/dl; intravenous: creatinine > 1.3 mg/dl) and continued. All patients were routinely administered low molecular weight heparin in prophylactic dose.
Atrial fibrillation was diagnosed based on electrocardiogram. All patients were ECG monitored continuously during the intensive care unit (ICU) stay and for the first 24 hours in the ward. Soon ECG was immediately performed in cases of irregular pulse, palpitation or symptoms related with possible AF.
In cases with AF, if required intravenous metoprolol was administered for heart rate control. For rhythm control, intravenous amiodarone was administered as intravenous 300 mg loading dose in 1 hour, followed by 900 mg in 24 hours and followed by oral amiodarone 200 mg three times a day. In refractory cases 450 mg additional intravenous infusion was given in 12 hours period. If no response was noted after 48 hours, electrical cardioversion was employed. Low molecular weight heparin dosage was switched to therapeutic interval. In cases of permanent AF development, oral warfarin was administered.
Primary outcome variables included mean time to extubation, ICU and postoperative hospital length of stay, incidence of renal dysfunction (based on the finding that peak creatinine value was 1.5 or greater times the preoperative value), postoperative stroke, postoperative total amount of blood loss, postoperative exploration for hemorrhage, number of used blood and blood products and in hospital mortality.
Statistical analyses were performed using SPSS software for Windows version 17.0 (Statistical Package for the Social Sciences Inc, Chicago, IL, USA). Continuous variables were expressed as ‘mean values ± standard deviation (SD)’. Categorical variables were expressed as number and percentages. Demographic characteristics and outcomes of the groups were compared using “independent samples t-test” for continuous variables, and, ‘chi-square test’ and ‘Fisher’s exact test’ for categorical variables. Statistical significance was set as ‘p < 0.05’.