Comparison of efficacy of three subanesthetic doses of ketamine in allaying procedural discomfort during establishment of subarachnoid block: A randomized double-blind trial

BACKGROUND: Procedural discomfort is experienced by patients during the establishment of subarachnoid block even after good preoperative counseling and adequate premedication. To enhance comfort, procedural sedation that would provide good analgesia, faster recovery, and amnesia is necessary. MATERIALS AND METHODS: Patients with American Society of Anesthesiologists Status I and II posted for elective surgeries under subarachnoid block were premedicated with injection midazolam 0.05 mg/kg and preloaded with 10 ml/kg ringer lactate solution. They were randomized into three groups of 30 each. Group K0.3 received ketamine 0.3 mg/kg, Group K0.4 received ketamine 0.4 mg/kg and Group K0.5 received ketamine 0.5 mg/kg intravenously. University of Michigan sedation score, ease of positioning, prick response, verbal response, hallucinations, recall of procedure, and patient satisfaction were evaluated. RESULTS: There was statistically significant difference in sedation among the three groups. Increased dose necessitated help of two persons to position the patient, which showed statistically significant difference. Verbal response was seen early in Group K0.3 (4.67 ± 2.84 min). There was no recall of experience of subarachnoid block procedure in any of the groups in spite of back muscle contraction or patient movement. Hence, all patients in all three groups were satisfied and were willing to undergo subarachnoid block, if the situation arises. CONCLUSION: Ketamine in the dose of 0.3 mg/kg provided sufficient sedation for allaying procedural discomfort due to less sedation, less positional difficulty, early verbal response, no hallucinations, no recall of performance of procedure, and good patient satisfaction.