Effect of different withdrawal time of dexmedetomidine on the quality of general anesthesia recovery

Objective To explore effect of different withdrawal time of dexmedetomidine (DEX) on the quality of general anesthesia recovery.Methods Eighty patients of ASA Ⅰ or Ⅱ undergoing lymph surgery were randomly assigned to four groups (n =20).Groups D1,D2 and D3 received DEX 0.5 μg/kg as bolus before induction,continued with 0.5 μg/(kg · h) by infusion until one hour,30 min before the end of operation and the end of operation,respectively.Group C received equal volume of normal saline.Mean artery pressure (MAP),heart rate (HR) and pulse oxygen saturation (SpO2) were observed during and after operation.Spontaneous respiration recovery time,eyes open time,extubation time,orientation recovery time,observer's assessment of alertness/sedation score (OAA/S),restlessness score (RS),and visual analogue scales (VAS) were observed after operation.Results For MAP and HR in Groups D2 and D3,there were no statistically significant difference during extubation compared to those at preoperation,but at the same time point,they were lower than those in group C (P ＜ 0.05).For groups C and D1,MAP and HR at extubation and 5 min after extubation were higher than those at preoperation (P ＜0.05).Spontaneous respiration recovery time,eyes open time,extubation time,orientation recovery time in group D3 were significantly longer than those in Group C (P ＜ 0.05),while there were no statistically significantly difference between groups D1,D2,and group C.OAA/S in group D3 was significantly lower than that in group C (P ＜ 0.05) at extubation.Incidence of restlessness,VAS,and cases given analgesic 2 hours after operation in groups D2 and D3 were significantly lower than those in groups C and D1.Compared to those in group C,dosages of propofol and remifentanil in groups D2 and D3 were significantly lower.Conclusions Dexmedetomidine administered of 0.5 μg/kg before induction,continued with infusion of 0.5 μg/(kg · h) until 30 min before the end of operation,may improve emergence,without influencing the awakening time of patients,and prolong the duration time of analgesia which comfort the patients. Key words: Dexmedetomidine/therapeutic use ;  Anesthesia, general ;  Anesthesia recovery period ;  Hemodynamics