Prophylactic use of intravenous ondansetron versus ketamine - midazolam combination for prevention of shivering during spinal anesthesia: A randomized double-blind placebo-controlled trial.

BACKGROUND: The aim of this study was to compare the efficacy intravenous (IV) ondansetron with ketamine plus midazolam for the prevention of shivering during spinal anesthesia (SA).

MATERIALS AND METHODS: Ninety patients, aged 18-65 years, undergoing lower extremity orthopedic surgery were included in the present study. SA was performed in all patients with hyperbaric bupivacaine 15 mg. The patients were randomly allocated to receive normal saline (Group C), ondansetron 8 mg IV (Group O) or ketamine 0.25 mg/kg IV plus midazolam 37.5 μg/kg IV (Group KM) immediately after SA. During surgery, shivering scores were recorded at 5 min intervals. The operating room temperature was maintained at 24°C.

RESULTS: The incidences of shivering were 18 (60%) in Group C, 6 (20%) in Group KM and 8 (26.6%) in Group O. The difference between Groups O and Group KM with Group C was statistically significant (P < 0.05). No significant difference was noted between Groups KM with Group O in this regard (P > 0.05). Peripheral and core temperature changes throughout surgery were not significantly different among three groups (P > 0.05). Incidence (%) of hallucination was not significantly different between the three groups (0, 3.3, 0 in Group O, Group KM, Group C respectively, P > 0.05).

CONCLUSION: Prophylactic use of ondansetron 8 mg IV was comparable to ketamine 0.25 mg/kg IV plus midazolam 37.5 μg/kg IV in preventing shivering during SA.