Comparison Of Analgesic Effect Of Different Concentrations Of Dexmedetomidine Combined With Ropivacaine On Continuous Adductor Tube Block After Total Knee Arthroplasty

Objective:To compare the analgesic effect of different concentrations of dexmedetomidine combined with ropivacaine on continuous adductor canal block(ACB)after total knee arthroplasty(TKA).Method:There were 150 patients who underwent the first unilateral TKA operation,regardless of sex,aged from 60 to 75 years old,ASA I-III grade.The patients were randomly divided into 5 groups(nasty 30): R group: 0.2% ropivacaine group;D1group: dexmedetomidine 0.5ug/ml combined with 0.2% ropivacaine;D2 group:dexmedetomidine 1.0ug/ml combined with 0.2% ropivacaine;D3 group:dexmedetomidine 1.5ug/ml combined with 0.2% ropivacaine;D4 group:dexmedetomidine 2.0ug/ml combined with 0.2% ropivacaine).The method of anesthesia was adductor canal block combined with general anesthesia.before anesthesia induction,the five groups were treated with ultrasound-guided ACB and perineural catheter.0.33% ropivacaine 10 ml was injected into adductor canal as load.Routine anesthesia induction was performed after 10 minutes.Total intravenous anesthesia was used during the operation.4mg ondansetron was injected intravenously 15 minutes before the end of the operation.After the operation,the ACB analgesia pump was turned on,the background dose was 4ml,the locking time was 0.5 hours,the duration was 48 hours,and holding the VAS score was ≤ 3.When the VAS score was more than 3,the nerve block pump should be given priority by the patient.If it was ineffective after 15 minutes,30 mg of Pentazoxine was injected intravenously.The VAS scores of resting and passive motion(knee joint passive flexion 45°)were recorded at 4,8,12,24,36 and 48 hours after operation.The first time of getting out of bed after operation and the time of 90° active flexion of knee joint were recorded.The number of self-controlled administration and the number of cases of using remedial analgesics within 48 hours were recorded.Adverse reactions such as nausea and vomiting,pruritus,hypotension(blood pressure drop > 20%),bradycardia(HR < 60 beats/ minutes)and excessive sedation(Ramsay score 5 or 6)were recorded.Result:There was no significant difference in VAS score at different time points among the five groups at rest(P > 0.05).During passive exercise,the VAS score in D1 group was lower than that in R group(P < 0.05),and the VAS score in D2,D3 and D4 groups was lower than that in D1 group(P < 0.05).There was no significant difference in VAS score between D2、D3 and D4 groups(P > 0.05).The first time of getting out of bed after operation and the 90 °active flexion of knee joint in group D2 were significantly shorter than those in the other groups(P < 0.05).The frequency of patient-controlled administration and the number of cases of additional analgesia in group R and D1 were higher than those in group D2,D3 and D4(P < 0.05).No adverse reactions such as excessive sedation,infection of catheterization site,nerve injury and local anesthetic poisoning were found in the five groups.Conclusion:For patients after total knee arthroplasty,self-controlled adductor canal block with dexmedetomidine 1.0ug/ml combined with 0.2% ropivacaine can provide a better analgesic effect and help to improve the prognosis.