Efficacy of Intravenous Butorphanol for Preventing Epidural-Related Maternal Fever (ERMF) During Epidural Labor...

The purpose of this research was to investigate whether intravenous low dose of butorphanol (1mg) at the onset of epidural analgesia (EA) can reduce the incidence of ERMF during labor.

Four hundred and twenty-four women, aged 18 to 40 years, BMI <=30 kg/m², more than 37 weeks' gestation, singleton pregnancy, American Society of Anesthesiology physical status I-II, normal maternal temperature and fetal heart rate, cervical dilation ≤ 3 cm, having EA were included in this double blinded randomized placebo-controlled trial. Women were randomized to receive intravenous butorphanol 1mL (Butor group) versus sterile saline 1mL (Con group), respectively. The primary outcome was the incidence of ERMF. Secondary outcomes included maternal temperature, pain score, the consumption of analgesic drugs, maternal and neonatal outcomes related to delivery.

A total of 424 subjects (212 subjects in Butor group and 212 subjects in Con group) were included in the final analysis. There was a significant decrease for the incidence of maternal fever in Butor group compared to Con group (37.3% versus 48.6%, P=0.019, T≥37.5°C; 6.1% versus 17.0%, P=0.000, T≥38.0°C). For secondary outcomes, butorphanol showed a protective effect in decreasing the sustained rise of maternal temperature from 2^th to 5^th hour after EA (P<0.05). And no statistical differences were noted in maternal pain scores and consumption of analgesic drugs (P>0.05). In addition, mild dizziness related to butrophanol was only appeared in few subjects in the first 2 hours after EA (P<0.05). No severe maternal or neonatal adverse effects were observed in all subjects.

A low dose of butorphanol intravenously used at the onset of EA in women undergoing vaginal delivery could effectively reduce the incidence of ERMF. Butorphanol may serve as a potential intervention for preventing ERMF in future.