Comparison Of Postoperative Analgesic Effect Between Intravenous Dexmedetomidine Assisted Femoral Nerve Block And Sciatic Nerve Combined With Femoral Nerve Block In Patients Undergoing Total Knee Arthroplasty

Background and Objectives: Total knee arthroplasty（TKA）is a severe traumatic procedure,and patients often experience severe pain after surgery.Severe pain can lead to delays in postoperative rehabilitation exercise and discharge.A femoral nerve block（FNB）combined with a sciatic nerve block（SNB）is widely used in TKA.However,the injury of the sciatic nerve after SNB is clinically reported,which seriously affects the quality of life.As an anesthetic adjuvant,dexmedetomidine（DEX）could reduce inflammation,attenuate stress response,and relieve pain.We hypothesized that dexmedetomidine assisted FNB can provide adequate postoperative analgesia for TKA patients.Therefore,we designed this study to compare the postoperative analgesic effect between dexmedetomidine assisted FNB and SNB combined with FNB in TKA.Methods: Eighty-eight patients undergoing TKA were included and randomly divided into two groups:（1）DF group: FNB（20ml 0.375% ropivacaine）,SNB（20ml saline） combined with DEX intravenously（0.6μg/kg before surgery,followed by DEX0.2–0.4μg/kg/h until articular closure）;（2）SF group: FNB（20ml 0.375% ropivacaine）,SNB（20ml 0.375% ropivacaine）combined with normal saline intravenously.All patients received general anesthesia and multimodal analgesia routinely.The primary endpoint was the pain visual analog scale（VAS）score during activities at postoperative24 hours,and the secondary outcome included VAS pain score at other time points,the incidence of adverse events,the use of the perioperative drug,the length of hospital stay,etc.Results: There was no significant statistical difference in VAS pain scores during activities at postoperative 24 hours,and no statistical difference in VAS pain scores at rest and exercise at other time points.There was no significant statistical difference between the two groups in the proportion of patients with the need for remedial analgesia 48 hours after surgery,and the mean duration of analgesia for patients with rescue analgesic requests was comparable between the two groups: 25.4 ± 6.3 hours in the DF group vs 24.8 ± 6.4 hours in the SF group（two-sample t-test,P=0.738）.The total intraoperative dose of sufentanil,the maintenance dose of propofol,and the dose of postoperative remedial analgesic was similar between the two groups（all P >0.05）.Patients in the SF group had a higher incidence of intraoperative hypotension and a higher incidence of ephedrine use（P =0.001）,while there was no statistical difference in the proportion of other vasoactive drugs.But the duration of extubation was significantly longer in the DF group than in the SF group（P < 0.001）.There were no significant statistical differences in the incidence of adverse events and the detail of postoperative rehabilitation.None of the patients had neurological damage.Conclusions: DEX assisted FNB could provide effective analgesia similar to SNB combined with FNB in TKA.