Comparison of efficacy of ketamine, midazolam and ketamine plus midazolam for prevention of shivering under spinal anaesthesia

Background: Ketamine and Midazolam have been reported to be effective for prevention and treatment of post-operative shivering following spinal anesthesia. The present study aimed at the comparison of i.v. ketamine, i.v. midazolam, midazolam and ketamine in combination, and placebo (saline) for the prevention of shivering in patients undergoing elective surgery under spinal anesthesia.Methods: This study was a double blinded, prospective, randomized controlled study of 120 cases between 18-60 years of age of either sex operated in the Uro-surgery department at KEM Hospital, Mumbai, after obtaining approval from institutional ethics committee and written informed consent from the patients.Results: Midazolam premedication reduces core body temperature by inhibiting tonic thermoregulatory vasoconstriction whereas, ketamine premedication increased core temperature. Core temperature remained unchanged in combination of the drugs which suggests that the thermoregulatory effects of a benzodiazepine receptor agonist and competitive receptor antagonist of NMDA oppose each other.Conclusions: This study concludes that use of a combination of ketamine plus midazolam was significantly superior to ketamine alone for the prevention of shivering.