Comparison of Dexmedetomidine and Alfentanil during Middle Ear Surgery

Background: We aimed to compare the effects of controlled hypotension with dexmedetomidine or alfentanil on hemodynamic parameters, surgeon satisfaction and bleeding in surgical field under N2O-free low-flow sevoflurane anesthesia in patients undergoing middle ear surgery. Materials and Methods: Forty patients, classified as ASA physical status I-II and candidates for middle ear surgery were randomly allocated into two groups by sealed-envelope method. Before induction Group D (n=20) received 0.1 mu g/kg/min dexmedetomidine for 10 minutes and Group A (n=20) received 20 mu g/kg alfentanil. Group D received 0.7 mu g/kg/hour maintenance dose of dexmedetomidine and Group A 1 mu g/kg/min alfentanil up until 30 minutes from the end of the surgery. All patients were had an induction with 6 mg/kg thiopental + 0.1mg/kg vecuronium bromide. Following intubation 3% sevoflurane was administered in a mixture of 2.0 L/min O-2 + 2.0 L/min air and this was followed by low-flow anesthesia to deliver 0.5 L/min O-2 + 0.5 L/min air. During the operation, controlled hypotension level was adjusted to have a systolic blood pressure of 80-90 mmHg and mean arterial pressure of 50-65 mmHg. Hemodynamic parameters were recorded with five minutes intervals. The surgeon, blinded to the study drugs, assessed amounts of bleeding in the operative field and surgeon satisfaction. Results: Achieving the desired hypotension levels happened later in Group D. At the stage of membrane placement, targeted mean arterial pressures were achieved in both groups. Three patients in Group D required short-term nitroglycerine infusion to reach the desired hypotension levels. The amounts of bleeding and surgeon satisfaction were equal in both groups. The return of hypotensive effect of dexmedetomidine was slower once it was stopped. In Group A, postoperative nausea and vomiting were frequently observed and 0.1 mg doses of naloxone were administered to four patients for two times after extubation. Conclusion: Although additional hypotensive agent required in dexmedetomidine group and desired hypotension levels were happened lately, there was no difference in the amount of bleeding, surgical view and surgeon satisfaction between dexmedetomidine and alfentanil.