Intravenous injection of butorphanol prevents shivering of parturients undergoing cesarean section under epidural anesthesia: a randomized controlled trial

Abstract

Background The objective of this study was to assess the inhibitory effect of intravenous injection of butorphanol on the shivering in those parturients who underwent cesarean section (CS) under epidural anesthesia (EA). Methods 160 parturients planned for elective CS under EA were enrolled and finally 155 of them were included in this trial and randomly allocated to 4 groups. Before epidural anesthesia, parturients in Group A, B and C were respectively injected 7.5μg/kg, 5μg/kg and 2.5μg/kg butorphanol (100ug/ml) while none in Group D was given any drug. The incidence, duration and intensity of shivering, hemodynamic parameters of parturients, Apgar score of neonates, analysis of blood gas of umbilical cord and adverse events were recorded. Results The demographic characteristics of parturients of the four groups were similar. Compared with the control group (Group D), statistically significant attenuation of shivering was seen in the parturients of Group A and Group B. The incidence, intensity and duration of shivering of the Group A and Group B were all lower than those of the control group, but there was no statistical difference in the incidence, severity or duration time of shivering among groups receiving butorphanol. No patient displayed grade 4 shivering. There were no significant differences among the groups with mean arterial pressure (MAP), heart rate (HR), pulse oxygen saturation (SpO2), respiratory rate (RR) after administration of butorphanol. The incidences of most adverse effects such as nausea and vomiting, respiratory depression, and hypotension were also not seen statistical difference among the four groups. However, compared with other three groups, sedation parameter increased in Group A. Compared with Groups C and Group D, incidences of dizziness increased in Group A and Group B. There was no significant difference in Apgar score, PH, PCO2, PO2, HCO3- and lactic acid value among the newborns of the four groups. Conclusion The prophylactic administration of intravenous butorphanol 0.75μg/kg or 0.5μg/kg is effective on inhibiting shivering and can be safely used in parturients undergoing CS under EA, but 0.5μg/kg is more suitable because of less sedation. Dizziness of parturients should be monitored whichever dose is used.