Anesthetic protocol
Attending anesthesiologist managed the anesthesia process. After establishing routine patient monitoring (heart rate, noninvasive blood pressure, pulse oximetry, and end tidal CO2), anesthesia was induced with an intravenous premedication of 2 μg/kg fentanyl, 0.03 mg/kg midazolam, 5 mg/kg sodium thiopental, and 0.5 mg/kg atracurium. Endotracheal tube with a suitable size, a high-volume, and a low-pressure cuff was inserted for the patients. Invasive monitoring of blood pressure through radial artery was applied for all patients after induction. Anesthesia was maintained with infusion of propofol 100–200 μg/kg/min as well as 30/70% of O2/N2O mixture to maintain MAP around 70 mmHg.