Controlled Hypotension With Desflurane Combined With Esmolol or Dexmedetomidine During Tympanoplasty in Adults: A Double-Blind, Randomized, Controlled Trial

BACKGROUND: Controlled hypotension is a technique that is used to limit intraoperative blood loss to provide the best possible Surgical field during surgery. OBJECTIVE: The aim of this double-blind, randomized, controlled study was to compare the effects of desflurane combined with esmotol or dexmedetomidine on the amount of blood in the surgical field, recovery time, and tolerability in adult patients undergoing tympanoplasty. METHODS: Turkish patients aged IS to 60 years, classified as American Society of Anesthesiologists physical status I or II, who were scheduled for tympanoplasty were randomly divided into 2 groups: the esmolol group or the dexmedetomidine group. After the anesthesia induction in the esmolol group, a loading dose of esmolol was infused intravenously over 1 minute at 1 mg/kg, followed by a maintenance rate of 0.4 to 0.8 mg/kg/h. In the dexmedetomidine group, a loading dose of dexmedetomidine was infused intravenously over 10 minutes at a rate of 1 mu g/kg, followed by a maintenance rate of 0.4 to 0.8 mu g/kg/h. The infusion rates were then titrated to maintain mean arterial pressure (MAP) of 65 to 7 5 mm Hg. General anesthesia was maintained with desflurane 4% to 6%. Heart rate (HR) and MAP were recorded during anesthesia. The following 6-point scale was used to assess the amount of bleeding in the operative field: 0 = no bleeding, a virtually bloodless field; 1 = bleeding that was so mild that it was not a surgical nuisance; 2 = moderate bleeding that was a nuisance but did not interfere with accurate dissection; 3 = moderate bleeding that moderately compromised surgical dissection; 4 = bleeding that was heavy but controllable and that significantly interfered with surgical dissection; and 5 = massive bleeding that was uncontrollable and made dissection impossible. Scores ! 2 were considered to be optimal surgical conditions. The sedation score was determined at 15, 30, and 60 minutes after tracheal extubation using the following scale: 1. = anxious, agitated, or restless; 2 cooperative, oriented, and tranquil; 3 = responsive to commands; 4 = asleep, but with brisk response to light, glabellar tap, or loud auditory stimulus; 5 = asleep, sluggish response to glabellar tap or auditory stimulus; and 6 = asleep, no response. Time to extubation and to total recovery from anesthesia (Aldrete score >= 9 on a scale of 0-10), adverse effects (eg, intraoperative hypotension [blood pressure <65 mm Hg], bradycardia [HR <50 beats/min]), intraoperative fentanyl consumption, and postoperative nausea and vomiting were recorded. Arterial blood gas analysis and kidney and liver function tests were conducted. All patients were evaluated by the same attending surgeon and anesthesiologist, both of whom were blinded to the administered study drugs. RESULTS: Fifty-two consecutive white patients undergoing tympanoplasty were identified. Two patients had to be excluded because of hypertension and 2 refused to participate. Forty-eight patients were equally randomized to either the esmolol group (n = 24 [16 women, 8 men]; mean [SD] age, 38.4 [10.5] years) or the dexmedetomidine group (n = 24 [17 women, 7 men]; mean age, 35.5 [14.7] years). Sedation scores were not collected for I patient in the esmolol group; therefore, analysis was conducted for 23 patients. The median (range) of the scores for the amount of blood in the surgical field in the esmolol and dexmedetomidine groups was 1 (0-3) and 1 (0-2), respectively (P = NS). Mean intracoperative fentanyl consumption in the esmolol group was significantly higher than in the dexmedetomidine group (50.0 [3-0] vs 25.0 [2-5] mu g/min; P = 0.002). In the esmolol group, the mean times to extubation and to recovery from anesthesia were significantly shorter than those of the dexmedetomidine group (7.0 [1.4] vs 9.1 [1.9] minutes, respectively; 5.9 [2.1] vs 7.9 [2.3] minutes; both, P = 0.001). The mean sedation scores were significantly lower in the esmolol group (n = 23, because of intent-to-treat analysis) compared with the dexmedetomidine group at 15 minutes (2.5 [0.6] vs 3.6 [0.5]; P = 0.001) and 30 minutes (2.6 [0.6] vs 3.3 [0.6]; P = 0.001) postoperatively. No significant differences were found between the study groups in regard to blood urea nitrogen or creatinine concentration, aspartate aminotransferase or alanine aminotransferase activities, pH, partial pressure of carbon dioxide, or bicarbonate, before or after the operation. CONCLUSIONS: Both esmolol and dexmedetomidine, combined with desflurane, provided an effective and well-tolerated method of achieving controlled hypotension to limit the amount of blood in the surgical field in these adult patients undergoing tympanoplasty. Esmolol was associated with significantly shorter extubation and recovery times and significantly less postoperative sedation compared with dexmedetomidine. (Curr Ther Res Clin Exp. 2009;70:197-208) (C) 2009 Excerpta Medica Inc.