intrathecal fentanyl for prevention of shivering in spinal anesthesia in cesarean section

background: shivering is one of the common problems in spinal anesthesia. the objective of the present study was to evaluate the effect of intrathecal fentanyl (25 μg) on incidence and severity of intraoperative and postoperative shivering. methods: a double-blind randomized controlled study was conducted in eighty healthy women (asa physical status i) scheduled for elective cesarean section under spinal anesthesia. subjects were randomly divided into two equal groups. the patients received 12.5 mg (2.5ml) of 0.5% hyperbaric bupivacaine combined with 25 μg (0.5 ml) fentanyl in group f as a study group and 12.5 mg (2.5ml) of 0.5 % hyperbaric bupivacaine combined with 0.5 ml normal saline in group s as a control group. incidence of shivering during 30 and 60 minutes of surgery and recovery and complications were evaluated. results: the total incidence of shivering in group f was significantly lower than group s (10% in group f 75% in group s, p< 0.0001). almost all patients started shivering in the first hour after spinal anesthesia and the rate of shivering especially in second 30 minutes was higher than first 30 minutes in both groups. none in group f but 22 patients (55%) in group s had shivering during recovery and all of them reported shivering at the first 30 minute at recovery. the severity of shivering in group f was significantly lower than group s (p < 0.0001). conclusion: intrathecal bupivacaine combined with fentanyl is associated with a lower incidence and severity of shivering.