Comparison of the Effects of Four Subdoses of Dextroketamine to Reduce Pain during Posterior Brachial Plexus Block: A Randomized Double Blind Study

BACKGROUND The needle puncture produces discomfort during regional anesthesia. Sedation and local anesthesia are used to promote analgesia and amnesia. The main objective of this study was to compare the efficacy of four subanesthetic doses of dextroketamine for pain relief during brachial plexus block via the posterior approach. MATERIALS AND METHODS Patients American Society of Anesthesiology I and II programed for elective surgery under brachial plexus block were distributed at randomized into four groups of twenty patients. Group A received dextroketamine 0.1 mg/kg, Group B received dextroketamine 0.15 mg/kg, Group C received dextroketamine 0.2 mg/kg, and Group D received dextroketamine 0.25 mg/kg. Sedation, facility to positioning, reaction to pinprick, nystagmus, hallucination, tachycardia, elevation of systolic blood pressure or cardiac rate, reduction in SpO2 (<96%), apnea, airway obstruction, collateral effects, and patient satisfaction were monitored. RESULTS There is a positive correlation between increasing dose of ketamine and the degree of sedation and easiness to position the patient on the table. There exists a negative correlation associated between increasing the dose of ketamine and the response to pinprick, as also to the incidence of hallucination. CONCLUSION Dextroketamine in doses of 0.1 mg/kg provide sufficient sedation to maintain the patient in position for brachial plexus block and for the relief of pain in 55% of them during the procedure, without hemodynamic variation. The pain relief and collateral effects are dose-dependent.