Effects of dexmedetomidine on stress reaction and extubation quality in elderly patients undergoing total knee arthroplasty with general anesthesia

Objective To investigate effects of dexmedetomidine on stress reaction and extubation quality in elderly patients undergoing total knee arthroplasty(TKA)with general anesthesia.Methods Forty elderly patients with ASA Ⅰ-Ⅲ,aged 65-78years old,undergoing TKA with general anesthesia,were randomly divided into Dex group(group D)and normal saline group(group C).D exmedetomidine was given with 0.5μg/kg within 10min before anesthesia induction and followed with 0.4μg·kg-1·h-1 in group D.The equal volume of normal saline was infused in group C.HR,MAP were observed at the time before dexmedetomidine infusion(T0),10 min after dexmedetomidine infusion(T1),immediately after intubation(T2),skin incision(T3),implantation of bone cement immediately(T4),surgery completion(T5)and after extubation(T6).The plasma concentration of epinephrine and norepinephrine were detected at T0,T2and T6.The intraoperative use of vasoactive drug was recorded.The respiratory recovery time,revival time,extubation time,bucking score and restlessness score were compared.Results Compared with T0,MAP at T1-T5 in group D and at T3,T4 in group C were decreased significantly(P0.05),HR at T4,T5in group D were decreased(P0.05),the concentration of E and NE at T2 and T6 in group C were increased(P0.05).Compared with group C,MAP at T1-T6in group D were decreased,as well as HR at T2-T6(P0.05),the concentration of E and NE at T2 and T6 in group D were significantly decreased(P0.05).13(65%)cases scored 1 in bucking and 17(85%)scored 0-1 in restless in group D,that were more than those in group C which were 5(25%)and 12(60%)respectly(P0.05).There was no difference in respiratory time,revival time and extubation time between the two groups.Conclusion The application of dexmedetomidine in the aged receiving TKA with general anesthesia could maintain stable hemodynamic index,decrease stress reaction and prevent adverse reactions during intubation and extubation,not affect the wake-up time.