A comparison of prophylactic use of meperidine, meperidine plus dexamethasone, and ketamine plus midazolam for preventing of shivering during spinal anesthesia: a randomized, double-blind, placebo-controlled study.

Study Objectives: The aim of this study is to compare the efficacy of combination of meperidine and dexamethasone with that of placebo, meperidine alone, and the combination of ketamine and midazolam in preventing shivering during spinal anesthesia.

Design: This is a prospective, placebo-controlled study.

Setting: The setting is at an operating room of a university-based teaching hospital.

Patients: Two hundred American Society of Anesthesiologists I and II patients undergoing orthopedic and urologic surgery under spinal anesthesia were included.

Interventions: Subarachnoid anesthesia was performed by using 15mg of 0.5% hyperbaric bupivacaine. Patients were randomly allocated to receive saline (placebo, group C), meperidine 0.4mg/kg (group Me), ketamine 0.25mg/kg plus midazolam 37.5μg/kg (group KMi), and meperidine 0.2mg/kg plus dexamethasone 0.1mg/kg (group MeD). All drugs were given as an intravenous bolus immediately after intrathecal injection.

Measurements: During surgery and stay in the recovery room, shivering score, blood pressure, and some other adverse effects were recorded at 5-minute intervals. Axillary and tympanic temperatures were recorded at 15-minute intervals during the perioperative period.

Main Results: The incidence of shivering after 30minutes of spinal anesthesia in groups C, Me, KMi, and MeD was 64%, 20%, 20%, and 4%, respectively, which was significantly higher in group C compared with other groups (P<.0001). Regarding adverse effects, there was no significant difference between groups (P≥.2). Axillary temperature significantly increased in the 15th-120th-minute interval in groups Me, KMi, and MeD (P<.0001) and in group MeD was higher than that in other groups. Core temperature decreased in the 15th-120th-minute interval in group MeD, lower than that in other groups (P<.0001).

Conclusions: Prophylactic use of meperidine 0.2mg/kg plus dexamethasone 0.1mg/kg was more effective than meperidine 0.4mg/kg as a sole agent or the combination of ketamine 0.25mg/kg and midazolam 37.5μg/kg in preventing shivering resulting from spinal anesthesia.