Effect of Ketamine Supplementation in Axillary Plexus Blockade: A Comparative Study.

Introduction: Axillary brachial plexus block is a widely used regional anesthesia technique for below-elbow surgeries. The use of adjuvant medications can influence block characteristics and postoperative pain experience. This randomized, prospective, single-blind comparative study aimed to evaluate whether ketamine, administered intravenously or regionally with ropivacaine, affects postoperative analgesia, rebound pain, and the onset time of sensory and motor block.

Methods: A randomized, prospective, single-blind comparative study was performed in patients undergoing ultrasound-guided axillary brachial plexus block for below-elbow surgery. Participants were assigned to three groups: group 1 (control, ropivacaine alone), group 2 (intravenous ketamine plus ropivacaine), or group 3 (regional ketamine plus ropivacaine). Onset of sensory and motor block, postoperative pain intensity using the numerical rating scale (NRS), need for rescue analgesia, and adverse effects during the first 24 hours were recorded and compared.

Results: The study included 81 patients (49 men and 32 women) with a mean age of 44.27±17.61 years (range: 16-81 years). Among them, 28 patients were in group 1, 27 patients in group 2, and 26 patients in group 3. Univariate analysis showed that both regional and intravenous ketamine administration were associated with faster onset of blockade (p<0.0005) and significantly lower NRS scores than the local anesthetic alone, at 16, 20, and 24 hours after the end of surgery (p=0.049, p=0.009, and p=0.006, respectively). No statistically significant difference was observed in motor block scores (p=0.329) and postoperative opioid (tramadol) intake (p=0.888) among the three groups.

Conclusions: Intravenous and regional addition of ketamine to ropivacaine solution improved postoperative analgesia equally by attenuating rebound pain and reducing the onset time of sensory and motor block. More high-quality studies are needed to fully elucidate the role of ketamine in axillary brachial plexus block.