Feasibility of dexmedetomidine assisting sevoflurane for controlled hypotension in endoscopic sinus surgery

Objective  To explore the feasibility of dexmedetomidine as an adjuvant of sevoflurane for controlled hypotension in endoscopic sinus surgery. Methods  Forty-eight patients (ASA Ⅰor Ⅱ) scheduled for endoscopic sinus surgery were randomly assigned into two groups ( n =24): control group (group I) and dexmedetomidine group (group Ⅱ). In both groups, intravenous injection of midazolam, propofol, fentanyl, and atracurium besilate was given to induce anesthesia, and propofol, fentanyl, atracurium besilate, together with sevoflurane inhalation were used to maintain anesthesia. The radial artery was cannulated to monitor the invasive mean arterial pressure (MAP). Controlled hypotension was induced by adjusting the sevoflurane concentration in group Ⅰ. In group Ⅱ, within 15min to 30min before the induction of anesthesia, dexmedetomidine was administered in a dose of 0.8μg/kg via intravenous infusion pump, then maintained at 0.4μg/(kg·h). Sevoflurane concentration was adjusted to maintain the target blood pressure at the beginning of surgery. The MAP was maintained at 65-75mmHg up to the end of operation. Meanwhile, the heart rate (HR), MAP, epinephrine (E), and norepinephrine (NE) concentrations were recorded at the time of induction of anesthesia (T0), beginning of controlled hypotension (T1), 30min after controlled hypotension (T2), and at the time when extubation was performed (T3). Blood gas analysis and determination of lactic acid concentration were conducted using the blood drawn from the radial artery during the operation. The surgical field quality was assessed based on Fromme scores of surgical field quality (SSFQ). Meanwhile, the dose of sevoflurane, propofol, and fentanyl, MAP, the recovery time of anesthesia, and the incidence rate of untoward effects were recorded. Results  The doses of propofol, fentanyl and sevoflurane, and MAC value in group Ⅱwas significantly diminished compared with group Ⅰ( P ＜0.01). In addition, the surgical field quality was better, whereas SSFQ was obviously lower in group Ⅱ( P ＜0.05). The HR at the time of T0 to T3, and the MAP, E, and NE at the time of T0 and T3 in group Ⅱwere obviously lower compared with group Ⅰ( P ＜0.05). The results of blood gas analysis and lactic acid, and the time of regaining consciousness and extubation showed no statistical difference between the two groups ( P ＞0.05). Moreover, the incidence rates of nose distending pain, headache, delirium, and shivering were obviously lower in group Ⅱ( P ＜0.05). However, the incidence rate of bradycardia needing intervention was higher in group Ⅱthan in group Ⅰ. No severe cardiovascular emergency was noted in the two groups. Conclusion  Dexmedetomidine can reduce the dose of anesthetic drugs, improve the cardiovascular stability during the perioperative period, accelerate the time to recovery of consciousness, and is safe and effective in assisting controlled hypotension during endoscopic sinus surgery.