Effects of Intravenous Ketamine, Butorphanol and Fentanyl for the Management of Intraoperative Shivering under Spinal Anaesthesia- A Randomised Clinical Trial

Introduction: Neuraxial block can cause intraoperative shivering. Though, so many drugs have been studied for treatment of shivering, none has been found ideal. N-methyl-D-aspartate (NMDA) antagonist like ketamine, k-opioid receptor agonist butorphanol and μ receptors agonist fentanyl have shown antishivering effect but each one has its own demerits.

Aim: To examine the efficacy of ketamine, butorphanol, and fentanyl in suppressing shivering under spinal anaesthesia in elective lower abdomen and lower limb surgery.

Materials and Methods: The double-blind, randomised trial was conducted between June 2011 to September 2013. A total of 90 patients, posted for surgery under spinal anaesthesia, were randomly allocated into three groups of 30 each. After giving spinal anaesthesia, patients who developed shivering (grade 3 or more), lasting for more than 3 minutes, the study drugs were administered. Patients in Group I received ketamine (0.5 mg/kg), Group II received butorphanol (0.02 mg/kg) and Group III received fentanyl (1 μg/kg), intravenously. Time taken to control shivering, sedation and any side-effects nausea and vomiting were assessed. The dose was given over 60 seconds and the time duration for the complete disappearance of shivering was noted (after the drug administration) at 2 min, 5 min, 10 min, 20 min, and 30 min. The sedation score was determined after 10 minutes of administering drug. Comparison of the observations among different groups was done and statistically analysed using Fisher-exact test, ANOVA, Chi-square test.

Results: Shivering control time was much shorter in Group II (3.6±1.20 min) than in Group I (3.867±1.676 min), but significantly longer in Group III (5.467±2.047 min). Mean age of Group I, II and III was 37.6, 34, 36.7 respectively. Reappearance of shivering was substantially more common in Group III (20%) than in Groups-I (0%) and II (0%).

Conclusion: Ketamine, buterophanol and fentanyl are equally effective for controlling shivering at 10 minutes after the administrating of study drugs but butorphanol is faster acting, followed by ketamine and then fentanyl to control of shivering.