Comparison of prophylactic use of ketamine, tramadol, and dexmedetomidine for prevention of shivering after spinal anesthesia

BACKGROUND AND AIMS: Shivering after spinal anesthesia is a common complication and can occur in as many as 40%–70% of patients after regional anesthesia. This shivering, apart from its physiological and hemodynamic effects, has been described as even worse than surgical pain. The aim of the study was to evaluate and compare the effectiveness of prophylactic use of intravenous (IV) ketamine, dexmedetomidine, and tramadol for prevention of shivering after spinal anesthesia. MATERIAL AND METHODS: Two hundred American Society of Anesthesiologists physical status I and II patients subjected to spinal anesthesia were included in the study. The subjects were randomly divided into four groups to receive either ketamine 0.5 mg/kg IV or tramadol 0.5 mg/kg IV or dexmedetomidine 0.5 microgm/kg IV or 10 mL of 0.9% normal saline (NS). All the drugs/NS were administered as IV infusion over 10 min immediately before giving spinal anesthesia. Temperature (core and surface), heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure, peripheral oxygen saturation were assessed before giving the intrathecal injection and thereafter at 5 min intervals. Important side effects related to study drugs were also noted. RESULTS: Shivering after spinal anesthesia was comparatively better controlled in group receiving dexmedetomidine as compared to other groups (P = 0.022). However, the use of dexmedetomidine was associated with significant hypotension which responded to single dose of mephentermine (3 mg IV). Dexmedetomidine is a better agent for prevention of shivering after spinal anesthesia as compared to ketamine and tramadol. It also provides adequate sedation and improves the surgical conditions. CONCLUSION: Dexmedetomidine is effective and comparably better than tramadol or ketamine in preventing shivering after spinal anesthesia. Dexmedetomidine also provides sedation without respiratory depression and favorable surgical conditions. However, with its use a fall in blood pressure and heart rate is anticipated.