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Background and Aims Axillary brachial plexus block is an effective and safe method of anesthesia for forearm, wrist and hand surgeries. The addition of adjuvant drugs, such as ketamine, to peripheral nerve blocks prolongs and enhances their effect. The present study aimed at investigating the role of ketamine administration route in the onset time and duration of nerve block and at examining the impact of ketamine supplementation on postoperative analgesia and incidence of rebound pain after block resolution.

Methods Eighty-one patients were included in this single-blind comparative study, divided into Group 1 (Control), Group 2 (IV) and Group 3 (Regional). All three groups received 30 ml of ropivacaine 0.5% regionally. In addition, Group 2 received a bolus dose of 30 mg ketamine intravenously, while Group 3 received 30 mg ketamine regionally. Time of establishment of sensory and motor blockade, the degree of blockade, duration of analgesia, patients‘ postoperative pain intensity (in Numerical Rating Scale-NRS), dose of opioid administered postoperatively and possible side effects of the blockade were recorded.

Results Both regional and intravenous ketamine supplementation of ropivacaine were associated with faster onset of blockade (p<0.0005) and lower rebound pain NRS scores at 16, 20 and 24 hours postoperatively than local anesthetic alone (p=0.049, 0.009 and 0.006, respectively.) No significant difference was observed in motor block scores and postoperative opioid intake among the three groups.

Conclusions Intravenous and regional addition of ketamine to ropivacaine solution for axillary branchial plexus block reduced the onset time of sensory and motor block and improved postoperative analgesia by attenuating rebound pain.