Evaluation of adjuvant rasemic ketamine in terms of effectiveness and neurotoxicity in sciatic nerve blockade

Objective: The aim of this study was to determine whether different doses ofketamine in combination with bupivacaine has effect on block durations in a rat modelof sciatic nerve blockade without causing nerve damage.Materials and Methods: Sixty-four Sprague-Dawley, female rats were includedinto study. Rats were anesthetized with eter and then the sciatic nerves were exposed bylateral incision on posterior approach. The test dose was injected beneath the fasciasurrounding the nerve without any damage to epineurium and perineurium. The groupsaccording to the test doses were: Sham group (n=8); Saline group (n=8), 0.2 mL saline;Bup group (n=8), 0.1 mL 0.5% bupivacaine+0.1 mL saline; Ket0.5 group (n=8), 0.1 mLketamine 0.5 mg/kg+0.1 mL saline; Ket1 group (n=8), 0.1 mL ketamine 1 mg/kg+ 0.1mL saline; BupKet0.5 group (n=8), 0.1 mL 0.5% bupivacaine+ 0.1 mL ketamine 0.5mg/kg; BupKet1 group (n=8), 0.1 mL 0.5% bupivacaine ve 0.1 mL ketamine 1 mg/kg.The durations of proprioceptive, sensorial and motor blockade were evaluated by aninvestigator blinded to the study groups. After neurobehavioral examination, the sciaticnerves were removed at either 24 hours or 14 days and were analyzed for perineuralinflammation and nerve damage.Results: Ketamine (0,5 mg/kg) in combination with bupivacaine prolonged thedurations of proprioceptive, motor and sensorial block durations about %41, % 23, %33rates, respectively. Ketamine (1mg/kg) combination with bupivacaine prolonged thedurations of proprioceptive, motor and sensorial block durations about %45, % 37, %31rates, respectively. While sole injection of ketamine to the sciatic nerve did not develop46motor block, provided a shorter proprioceptive block than other groups and a similarduration for sensorial block. It was seen that the changes in durations of block were notdose-dependent. There were no statistical difference between groups according toneurotoxicity.Conclusion: We think that ketamine may be a good adjuvant agent and therasemic form can be safe in peripheral nerve blocks.Key words: Sciatic nerve blockade, Rasemic ketamine, Bupivacaine,Neurotoxicity.