Effect Of Different Administration Methods Of Dexmedetomidine Combined With Nerve Block On Postoperative Analgesia In Total Knee Arthroplasty

Background and Objectives: It has been reported that dexmedetomidine can significantly prolong the time of nerve block analgesia when used as an adjuvant of local anesthetics.However,it has not been reported whether perineural or systemic dexmedetomidine is more beneficial for postoperative recovery in patients undergoing total knee arthroplasty(TKA).To this end,we evaluated the effects of two different dexmedetomidine administration modes of perineural and systemic on postoperative analgesia in TKA patients.Methods: 1.The research object :We randomly assigned the patients undergoing TKA under general anesthesia combined with femoral nerve block(FNB)and sciatic nerve block(SNB)to one of three groups:(1)perineural dexmedetomidine group(DP): local anesthetic formula:0.25% Ropivacaine 40ml+dexmedetomidine 0.5μg/kg,intravenous solution 10 ml saline;(2)dexmedetomidine systemic intravenous administration group(DS): local anesthetic formula:0.25% ropivacaine 40 ml +1ml normal saline,intravenous solution dexmedetomidine 0.5μg/kg 10 ml;(3)Control group(C): local anesthetic formula: 0.25% ropivacaine 40 ml+1ml normal saline,Intravenous solution 10 ml saline.All intravenous solutions were infused 15 minutes before the operation.2.Observation indicators: Main outcome measures: The time to the first postoperative report of surgical site pain.Secondary outcome indicators: patients’ VAS score at rest and activity at 6,12,24,48 and 72 hours after surgery,patients’ need for postoperative recovery analgesia,satisfaction of pain control at 72 hours after surgery,time to get out of bed for early rehabilitation exercise for the first time after surgery,patients’ satisfaction of sleep on one day after surgery,Results: The average of first reported pain duration(26.0h [22.0 h —30.0 h])in the DP group was significantly longer than that in the DS group(22.4 h [18h to 26.8h])and the C group(22.9h [19.5h to 26.3h],p=0.001).For this result there was no significant difference between the DS and the C group.Compared with DS and C groups,patients in DP group had lower resting VAS scores at 24,48 and 72 hours after surgery,lower activity VAS scores at 12,24 and 48 hours after surgery,there was no significant difference between the DS and the C group.Compared with DS and C groups,the amount of postoperative opioids in DP group was also significantly reduced,and the number of postoperative rescue and analgesia was significantly reduced,with statistical difference(p < 0.05),there was no significant difference between the DS and the C group.The sleep satisfaction of patients in DP group on the first night after surgery and the satisfaction of pain control at 72 hours after surgery were both higher than those in DS group and C group,with statistical significance(p < 0.05),there was no significant difference between the DS group and the C group(p > 0.05).There were no significant differences in the time of the first functional exercise out of bed,postoperative adverse reactions(including postoperative delirium,postoperative nausea and vomiting,and limb numbness)among the three groups(p > 0.05).Conclusions: Perineural administration of dexmedetomidine can significantly prolong the time to first report pain after TKA,relieve postoperative pain,reduce postoperative opioid dosage,and improve postoperative sleep quality and satisfaction with pain control.