Epidural clonidine combined with bupivacaine for analgesia in labor. Effects on mother and neonate.

Abstract

A double-blind study was conducted to assess the efficacy and the safety of epidural clonidine combined with bupivacaine for analgesia during labor. Two groups of pregnant healthy women were allocated randomly to receive either 10 mL 0.125% bupivacaine plain solution (group B, n = 10) or with 75 micrograms clonidine (group B + C, n = 12). Visual analog scale (VAS) scores were measured over 30 minutes after each epidural injection. Patients were monitored with an automated blood pressure device (Dinamap and a pulse oximeter), and fetal heart rate was measured with a cardiotocograph. Plasma clonidine concentrations were measured at birth in mothers and in the umbilical cord by radioimmunoassay. Visual analog scale scores were significantly lower in patients who received clonidine. Patients required a second epidural injection after 55 +/- 9 minutes in group B and 127 +/- 11 minutes in group B + C (P < .05). Visual analog scale scores were also significantly lower in group B + C than in group B, after the second injection. Decreases in arterial blood pressure were comparable in the two groups, and no patient experienced arterial oxygen desaturation or bradycardia. Fetal heart rate was decreased in group B + C at the time of the second injection. The duration of labor after epidural administration was prolonged in group B + C patients compared to group B (282 +/- 43 minutes and 169 +/- 26 minutes, respectively, P < .05). Apgar scores at 1 and 5 minutes were similar in both groups. Plasma clonidine concentrations were, respectively, 0.31 +/- 0.16 ng/mL 60 minutes after the first injection and 0.62 +/- 0.13 ng/mL at birth in mothers while plasma umbilical cord concentrations were 0.56 +/- 0.12 ng/mL. The study documents that clonidine improves epidural bupivacaine analgesia during labor and demonstrates transfer of the drug across the placenta. Therefore, a more extensive study is required to determine the incidence of possible side effects of clonidine in neonates.