 Anesthesia and surgery All patients underwent a standardized general anesthesia procedure. Induction used intravenous midazolam 1.5 mg and fentanyl 3-5 mcgkg of body weight and propofol 2 mgkg body weight. Anesthesia was maintained with 2 to 3 sevoflurane and 100 oxygen concentration. Neuromuscular blocking was maintained with intravenous vecuronium 0.1 mgkg body weight. All patients were monitored with indirect determinations of arterial pressure and heart rate using the standard technique as well as expired CO2 content and oxygen blood saturation. A nasogastric tube was placed in all patients during the operation and taken out at the end of the surgical procedure. Afterwards, all patients were extubated and transferred to the immediate postsurgical care unit with cardiovascular and oxygen monitoring. 