Effect of dexmedetomidine on stress responses during wake-up test in patients undergoing cerebral functional area operation performed under propofol combined with remifentanil anesthesia

Objective To investigate the effect of dexmedetomidine on the stress responses during wakeup test in patients undergoing cerebral functional area operation performed under propofol combined with remifentanil anesthesia.Methods Thirty-six ASA physical status Ⅰ or Ⅱ patients,undergoing cerebral functional area operation requiring wake-up test,aged 18-60 yr,weighing 50-70kg,were randomly divided into control group (group C) or dexmedetomidine group (group D) with 18 cases in each group.Dexmedetomidine 0.8 μg/kg was infused over 10 min before induction of anesthesia followed by infusion at 0.4 μg·kg-1 · h-1 in group D,while the equal volume of normal saline was infused in group C.Anesthesia was induced with target-controlled infusion of propofol and remifentanil and iv injection of cisatracurium.At 30 min prior to wake-up test,target-controlled infusion of propofol and application of mulscle relaxants were stopped,the target plasma concentration of remifentanil was decreased to 1 ng/ml,and in group D the infusion rate of dexmedetomidine was decreased to 0.1 μg·kg 1· h-1.Anesthesia time and consumption of anesthetics before wake-up test,wake-up time,and development of complications and intraoperative awareness during wake-up test were recorded.At 30 min prior to wake-up test (T1),immediately after wake-up (T2),at 5 min after wake-up (T3),and at 10 min after the anesthetic depth was deepened (T4),HR,mean arterial pressure and BIS value were recorded and blood samples were taken for determination of plasma concentrations of epinephrine (E) and norepinephrine (NE).Results Compared with group C,the consumption of propofol and remifentanil was significantly reduced before wake-up,the incidence of hypertension was decreased during wake-up test,and HR and plasma E and NE concentrations were decreased at each time point (P ＜ 0.05),and no significant difference in mean arterial pressure and BIS value was found in group D (P ＞ 0.05).Tachycardia,restlessness,bucking and awareness were not observed during wake-up test in group D.Conclusion Dexmedetomidine can inhibit the stress responses during wake-up test and raise the quality of wake-up test in patients undergoing cerebral functional area operation performed under propofol combined with remifentanil anesthesia. Key words: Dexmedetomidine;  Stress;  Propofol;  Piperidines;  Wake-up test