Minimum effective local anesthetic dose of intra-articular ropivacaine with dexmedetomidine for analgesia in patients undergoing knee arthroscopy / 临床麻醉学杂志

ABSTRACT

Objective To observe the minimum effective local anesthetic dose of intra-articular ropivacaine with dexmedetomidine for analgesia after knee arthroscopy in patients.Methods Seventy-two patients (35 males,37 females,aged 60-75 years,ASA grade Ⅰ or Ⅱ)undergoing knee arthro-scopy under total intravenous anesthesia were randomly divided into two groups (n =36 each)ropiv-acaine group (group R)and ropivacaine with dexmedetomidine group (group DR);Ropivacaine was injected intra-articularly in group C,and dexmedetomidine 1 μg/kg with ropivacaine was injected intra-articularly in group DR.ED50 of ropivacaine was determined by the sequence method.VAS score3 two hours after operation was rated as effective.The initial dose was 3 mg and according to the effective or ineffective results in previous patient,a dose of ropivacaine was decreased or increased 1.1 times to the previous patient.BP,HR,VAS Score,and OAA/S score were recorded five minutes preoperatively(T0 ),1 h (T1 ),2 h (T2 ),3 h (T3 ),6 h (T4 ),12 h (T5 ),24 h (T6 ),and 48 h (T7 ) after operation in two groups.Results There was no significant difference between the two groups with regard to the BP,HR,VAS Score,and OAA/S score.ED50 of ropivacaine for analgesia after knee arthroscopy was 0.31% (95%CI 0.30%-0.32%),and ED50 of ropivacaine with dexmedetomi-dine for analgesia after knee arthroscopy was 0.14% (95% CI 0.14%-0.1 5%). Conclusion Intra-articular administration of ropivacaine with dexmedetomidine could provide superior postoperative analgesia.The dose of ropivacaine for analgesia after knee arthroscopy should be reduced when combined with dexmedetomidine in patients.