Comparison of meperidine and fentanyl for prevention of shivering during spinal anesthesia

Abstract

Background: Shivering associated with spinal anesthesia is a frequent event, and the reported median incidence of shivering related to neuraxial anesthesia is up to 55% (Crowley and Buggy, 2008). The mechanism of shivering in patients undergoing spinal anesthesia is not clear, but hypothermia due to redistribution of heat caused by vasodilation below the level of a neuraxial block is suggested. Spinal anesthesia also impairs the thermoregulation system by inhibiting vasoconstriction. Shivering increases oxygen consumption, metabolic rate, lactic acidosis, carbon dioxide production, plasma catecholamines, and cardiac output. Shivering movement may interfere with monitoring of hemodynamics as well as increasing patient discomfort and distress. Therefore, it is very important to prevent shivering during spinal anesthesia.
Methods: Six hundred and fifty patients, using American Society of Anesthesiologists physical status I or II, aged 40-75 years scheduled for elective urologics surgery under spinal anesthesia were investigated. Patients with ASA physical status >II, Obesity (BMI>28kg/m2) Parkinson’s disease, dysautonomia or Rayaud‘s syndrome, ischemic heart disease or cerebrovascular disease requiring blood transfusion during surgery were excluded from the study. Patients were randomly divided into two groups; Meperidine (Group M, n =325) and fentanyl (Group F, n = 325) groups. Group M and F received meperidine 0.4 mg/kg or fentanyl 1.5 mcg/kg, respectively, in 100 ml of isotonic saline intravenously. All drugs were infused for 15 min by a blinded investigator before spinal anesthesia. Blood pressures, heart rates, body temperatures and side effects were checked before, during and after spinal anesthesia.
Results: The incidences and scores of shivering were not similar between the two groups. Shivering was seen in 15 (4.61%) patients who received meperidine, while in the fentanyl group, shivering occurred in 108 patients (33.2%). In the meperidine group compared with the fentanyl group, it was seen that there is significance in preventing intraoperative and postoperative shivering in recovery without increasing the side effects (P <0 .001). Blood pressure, body temperature and arterial oxygen saturation did not have a clinically significant change and they were not different between the two groups. Side effects of opioids were unremarkable.
Conclusion: We conclude that meperidine infusion in the periopertaive period significantly reduced shivering associated with spinal anaesthesia in urologic procedures. Meperidine is a better alternative than fentanyl for preventing shivering in patients during spinal anaesthesia (P<0.001) .

Keywords: Meperidine, fentanyl, shivering, spinal anesthesia.