Intraarticular Ketamine Extended the Duration of Lidocaine Analgesia. A Comparative Study with Bupivacaine in Patients Undergoing Knee Arthroscopic Surgeries

Background: The duration of lidocaine analgesia is shorter than that of bupivacaine. This study was designed to evaluate the efficacy of ketamine in extending the duration of intraarticular lidocaine 1% analgesia to reach that of bupivacaine 0.25%. Also, to evaluate the pain scores, tramadol consumption and the associated side effects. Methods: This randomized double-blind study was conducted on sixty patients ASA I and II and undergoing arthroscopic knee surgeries. The patients were allocated into 3 groups: ketamine-lidocaine group: where ketamine 1mg/kg was added to 20ml of intraarticular lidocaine 1%; lidocaine group: where 20ml of intraarticular lidocaine 1% was given and bupivacaine group: where 20ml of bupivacaine 0.25% was given. The duration of postoperative analgesia, the pain scores and total analgesic consumption in 24 hours were compared. Also, the hemodynamics and the occurrence of side effects were reported. Results: The duration of analgesia was prolonged and the pain scores at 4 hour were reduced in ketamine-lidocaine and bupivacaine treated groups when compared to lidocaine only group. However, no significant difference was detected between the groups as regards tramadol requirements in the 24 hours of the study period. The occurrence of vomiting was comparable between the studied groups. Conclusion: When ketamine 1mg/kg was added to intraarticular 20ml of lidocaine 1% it prolongs its duration to reach that of bupivacaine 0.25% in the same volume without significant side effects. However, the total analgesic needs in 24 hours were similar in the three studied groups.