Myocardial Protection and Anesthetic Agents

Fifty patients is included in this study. Routine monitorization included a 5-lead electrocardiogram (ECG), invasive arterial monitoring, pulse oximetry, capnography, temperature monitoring. Invasive arterial catheter were inserted under local anesthesia. Central venous catheter (jugular or subclavian) and esophageal heat probe were inserted after tracheal intubation.

Anesthesia induction was standardized in all patients and included 1 mg/kg propofol, 1 μg/kg fentanyl and 0.1 mg/kg vecuronium bromus to facilitate endotracheal intubation. The patients were divided into two groups by computer randomization method. Group R (n=25), remifentanil group and Group D (n=25) dexmedetomidine group. In the remifentanil group, anesthesia was maintained with 0.5-1.5% sevoflurane and 0.125-0.25 μg/kg/min remifentanil infusion. In the dexmedetomidine group anesthesia was maintained with 0.5-1.5% sevoflurane and 0.5 μg/kg dexmedetomidine loading dose during 10 minute and 0.3-0.9 μg/kg/min infusion.

Cardiopulmonary bypass (CPB) period was started after aort and venous cannulae were inserted. Mean arterial pressure, central venous pressure, venous oxygen saturation (SVO2) and arterial blood gase analysis were recorded. All blood samples include laktat, pyruvate, CKMB and Troponin-T were taken via the coronary sinus catheter at specific time intervals (precardiopulmonary bypass, 20 minutes after cross clamp, 20 minutes after removal cross clamp and 10 minutes after cardiopulmonary bypass).

Cardiopulmonary bypass time, aortic cross clamping time, the need of defibrillation/intraaortic balloon pumping (IABP)/extracorporeal membrane oxygenator (ECMO), urine output, positive inotropic agents requirement were recorded. At the end of surgery, the patients were transferred intensive care unit intubated and full monitorized.

Inclusion criteria

• Scheduled to open heart surgery
• American Society of Anesthesiologists (ASA) physical status of II-III

Exclusion criteria

• Emergency surgery, prior cardiac surgery, ejection fraction < 50%, restrictive or obstructive pulmonary disease, preoperative mechanical ventilation, intra-aortic balloon pump, chronic liver and renal failure.