The Analgesic Effect Of Different Doses Of Dexmedetomidine Combined With Ropivacaine For Adductor Canal Block After Knee Arthroplasty

Objective:To observe the value of different doses of dexmedetomidine combined with ropivacaine for adductor canal block on analgesia after knee joint replacement,and to vetify the effect of dexmedetomidine on the analgesic effect of local anesthetic,and to further explore the optimal dose of dexmedetomidine combined with ropivacaine for clinical application.Methods:A total of 120 patients who underwent unilateral knee arthroplasty in the operating room of the Affiliated Hospital of Qingdao University from March 2018 to September2018,were enrolled and randomly divided into four groups(A,B,C and D),30 patients in each group.All patients were given ultrasound-guidance adductor canal block at 30 min before the induction of the general anesthesia: the patients in group A were given0.375% ropivacaine 20 ml,the patients in group B were given 0.50?g/kg dexmedetomidine and 0.375% ropivacaine 20 ml,the patients in group C were given0.75?g/kg dexmedetomidine and 0.375% ropivacaine 20 ml,and the patients in group D were given 1.00 ?g/kg dexmedetomidine and 0.375% ropivacaine 20 ml.An intravenous analgesia pump was used for analgesia after surgery.The amount of sufentanil and propofol,the time for recovery of spontaneous breathing,emergence time and time for removal of LMA were recorded.Visual analogue scale(VAS)scores and Ramsay sedation scores were observed at 6h,12 h,24h and 48 h after surgery.The first pressing of intravenous analgesia pump was recorded.The amount of tramadol and the number of effective pressings of the intravenous analgesia pump were recorded within 48 h after surgery.The four groups were compared in terms of degree of satisfactions and incidence rate of adverse events after surgery.All datas were processed by SPSS 22.0 statistical software.The efficacy of different doses of dexmedetomidine combined with ropivacaine on analgesia in patients undergoing knee arthroplasty were analysed.Results:There were no obvious differences in the amount of sulfentnil and propofol,the time for recovery of spontaneous breathing,emergence time and time for removal of LMA in the four groups(P > 0.05).At 6h and 12 h after surgery,group B,C and D had a significantly lower VAS score than group A,group C and D had a significantly lower VAS score than group B(P < 0.05).There were no obvious differences in the Ramsay sedation scores between all groups at each time point after surgery(P > 0.05).Group B,C and D had a significantly lower amount of tramadol,the first and the number of effective pressings of the intravenous analgesia pump than group A within 48 h after surgery,the differences were significantly(P < 0.05).Group C and D had a significantly lower amount of tramadol and the first pressing and the number of effective pressings of the intravenous analgesia pump than group B,the differences were significantly(P < 0.05),but there was no difference between group C and group D(P > 0.05).Group B,C and D had a significantly higher degree of satisfaction than group A(P < 0.05).There were no significant differences incidence rates of postoperative hypotension,respiratory depression and bradycardia between the four groups(P > 0.05).Conclusion:Dexmedetomidine(0.75?g/kg)combined with ropivacaine(0.375%)20ml for adductor canal block can effectively alleviate pain after knee arthroplasty,and improve degree of patients satisfaction,and reduce the amount of analgesic drug used after surgery.