Clinical Effectiveness Comparison Of Different Doses Of Dexmedetomidine For Preventing And Treating Postoperative Remifentanil-induced Hyperalgesia

Objective:To observe the efficacy and safety of different doses of dexmedetomidine for preventing and treating remifentanil-induced hyperalgesia.Methods : Eighty patients(40-65 years old,ASA II or ?)scheduled for radical operation for esophageal carcinoma under general anesthesia were randomly divided into four groups(n=20 in each group): low dose(group LD),middle dose(group MD),high dose(group HD)group and control group(group C).Patients in group LD were given an intravenous infusion of 0.25?g/kg dexmedetomidine in 10 min before induction of anesthesia,and then received 0.25?g/(kg·h)dexmedetomidine consistently till 30 min before the end of the operation.Patients in group MD were given an intravenous infusion of 0.50?g/kg dexmedetomidine in 10 min before induction of anesthesia,and then received 0.50?g/(kg·h)dexmedetomidine consistently till 30 min before the end of the operation.Patients in group HD were given an intravenous infusion of 1.00?g/kg dexmedetomidine in 10 min before induction of anesthesia,and then received 1.00?g/(kg·h)dexmedetomidine consistently till 30 min before the end of the operation.Patients in group C were given corresponding volume saline.The hemodynamic changes of perianesthesia,the scores of improved OAA/S and VAS of rest pain and motion pain(at 10 min(T1),30 min(T2),1 h(T3),2h(T4),6h(T5),12h(T6),24h(T7))after extubation,the cumulative dose of analgesic in PCA and the incidences of adverse reactions for 24 h after surgery were observed and recorded.Results:1?There were no statistically significant differences among four groups in the aspects of fundamental state including age,sex,BMI(body mass index),operation time and extubation time.(P>0.05)2?Comparison of hemodynamic changes during anesthesia period?The fluctuation of blood pressure during placement of stomach tube and extubation were higher in group C and LD than other two groups,and the differences were statistically significant when compared with group C(P<0.05).?The changes of heart rate during placement of stomach tube and extubation were statistically significant higher in group C than group LD and MD(P<0.05).Patients in group HD had bradycardia in different degree when recevied an intravenous infusion of1.00?g/kg dexmedetomidine in 10 min(P<0.05).3?Comparison of VAS scores among four groups at each time point inactively:?Compared with group C,the VAS scores of patients in group LD at T1-T5 were statistically significant lower(P<0.05),and patients in group MD and HD at T1-T7 were statistically significant lower(P<0.05).?Compared with group LD,the VAS scores of patients in group MD at T1-T6 were statistically significant lower(P<0.05),and patients in group HD at T1-T7 were statistically significant lower(P<0.05).?Copmared with group MD,there were statistically significant lower scores of VAS in group HD at T1-T7(P<0.05).4?The VAS scores of motion pain in each group were 1 to 2 points higher at each time point than rest pain.But the comparisons among four groups were similar to the scores of VAS in inactive state.5?The scores of improved OAA/S among each group were in 1or 2 state,however,there were statistically significant lower scores in group C,LD and MD when compared with group HD(P<0.05).6?The cumulative dose of analgesic and the incidences of adverse reactions for 24 h after surgery in group LD,MD,and HD were statistically significant lower than group C(P<0.05).Conclusion:1?Intraoperative infusion of different doses of dexmedetomidine can relieve postoperative pain and attenuate high-dose remifentanil-induced hyperalgesia in different degree.2?Intraoperative infusion of high doses of dexmedetomidine(an intravenous infusion of 1.00?g/kg dexmedetomidine in 10 min before induction of anesthesia,and then received 1.00?g/(kg·h)dexmedetomidine consistently till 30 min before the end of the operation)will not be recommended because of its potential saftey risks.3?Intraoperative infusion of middle doses of dexmedetomidine can safely and efficiently relieve postoperative pain and attenuate high-dose remifentanil-induced hyperalgesia.Moreover,the quality of perioperative life and satisfaction of patients can also be increased.