Abstract: PURPOSE : To observe the effect and safety of controlled hypotension by dexmedetomidine in oral maxillofacial orthognathic surgery. METHODS : Forty patients undergoing orthognathic surgery were randomly divided into 2 groups: group D received dexmedetomidine (n=20), group NS received normal saline (n=20).After induction before the operation, dexmedetomidine 1.0 μg/kg was given intravenously within 10 min, then maintained at 0.5 μg/(kg·h) in group D, the same maintained speed of normal saline was given in group NS .Both groups were combined with propofol, remi-fentanyl, sevoflurane for controlled hypotension. The target MAP was maintained at 50-65 mmHg. HR, SBP, DBP and MAP were recorded before anesthesia and during the phase of controlled hypotension. And the dosage of propofol and remi-fentanyl in both groups was compared; meanwhile, the scores of surgical field quality (SSFQ) were assessed according to Fromme surgical field quality list. SPSS 11.0 software package was used for comparison of the 2 groups. RESULTS : During controlled hypotension ,MAP in both groups were significantly lower than those before anesthesia (P<0.01). MAP and HR in group D at T3(at the beginning of surgery), T4(15 min after surgery ), T5( 30 min after surgery) were significantly lower than that of group NS (P<0.05). HR in group NS at T3, T4, T5, and T6(60 min after surgery) were significantly higher than those before anesthesia (P<0.05). The dosage of propofol in group D was significantly lower than that in group NS (P<0.05). Compared with group NS, surgical field quality in group D were significantly better (P<0.05). CONCLUSIONS : Dexmedetomidine can be used safely and efficiently for controlled hypotension in oral maxillofacial orthognathic surgery, combined use of dexmedetomidine can avoid fluctuation in blood pressure and heart rate, make the hemodynamics more stable, and reduce the dosage of propofol, and achieve better surgical field quality.

Key words: Dexmedetomidine, Controlled hypotension, Orthognathic surgery