DOI: 10.4103/aam.aam_396_26 ISSN: 1596-3519

Evaluation of Analgesic Effects of Ketamine versus Dexmedetomidine as an Adjuvant to 0.2% Ropivacaine Infusion in Adductor Canal Block for Postoperative Analgesia following Unilateral Total Knee Replacement Surgery

Sahla Shamsudheen, Gokuldas Sekhara Menon, Nitu Puthenveettil

Abstract

Background:

Postoperative pain management is critical for recovery following total knee replacement (TKR). Significant pain following surgery is linked to TKR, and this discomfort might have a negative impact on the patient’s satisfaction, length of stay, and functional recovery. The adductor canal block (ACB) is preferred for its motor-sparing properties. This study compared the analgesic efficacy of ketamine and dexmedetomidine as adjuvants to ropivacaine infusion in ACB for patients undergoing unilateral TKR.

Methods:

In this prospective, randomized, comparative study, 44 patients (American Society of Anesthesiologists I–III) were divided into two equal groups. All received spinal anesthesia followed by an ultrasound-guided ACB with a catheter. Group A received 0.2% ropivacaine with ketamine (1 mg/kg) infusion, and Group B received 0.2% ropivacaine with dexmedetomidine (1 μg/kg) infusion at 8–10 mL/h for 24 h. Primary outcomes included a comparison of the requirement for rescue analgesia, while secondary outcomes included a comparison of pain scores, hemodynamic stability, and motor blockade.

Results:

The requirement for rescue analgesia was significantly higher in Group A (54.54%) compared to Group B (18.2%; P = 0.012). While numerical pain scores were generally comparable, Group B showed significantly lower pain at the 8 th h ( P = 0.045). Both groups maintained hemodynamic stability and demonstrated preserved motor power. Postoperative vomiting was significantly more frequent in Group A ( P = 0.035).

Conclusion:

Dexmedetomidine (1 μg/kg) is a more effective adjuvant than ketamine (1 mg/kg) for ropivacaine-based ACB, offering improved analgesia without adverse hemodynamic or motor effects.

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