Maternal and Neonatal Fentanyl and Bupivacaine Concentrations After Epidural Infusion During Labor

Abstract

Labor analgesia using continuous epidural infusions of low-dose bupivacaine and fentanyl may be maintained for many hours. We examined the potential for drug accumulation in both mother and neonate after these long-term infusions. Pregnant women receiving a 10-mL/h continuous infusion of labor analgesia with 0.125% bupivacaine and 2 micrograms/mL of fentanyl were evaluated. Maternal venous and umbilical venous drug concentrations were measured at delivery. Umbilical artery blood gases were obtained. Scanlon neurobehavioral testing was performed on all infants. Length of infusion times varied from 1 to 15 h. Maternal and neonatal drug concentrations remained relatively constant throughout the infusion period. All umbilical blood gas values and neurobehavioral scores were within normal limits. In conclusion, even when maintained for many hours, continuous infusion labor analgesia does not appear to result in significant fetal drug accumulation. No adverse neonatal effects were seen.

Advances in labor analgesia

“…Their short duration of action (60 to 90 minutes) is overcome by maintaining analgesia with a continuous epidural infusion. Doses commonly used for initiation and maintenance of neuraxial analgesia have been shown to be safe for both the mother and neonate 81,82. In contrast, neuraxial morphine has a much slower onset (30 to 60 minutes) and longer duration of action (12 to 24 hours) 83.…”

Practical Management of the Mother-Infant Nursing Couple

“…Infants whose mothers received bupivacaine epidural anesthesia were described to be less alert and have less ability to orient over the first month of life. Measurable effects on the neonate' s neurobehavior were seen in the study by Murray et al, 112 but not in the study by Bader et al, 15 who observed epidurals of fentanyl and bupivacaine from 1 to 15 hours of infusion and saw no signs of accumulation in the cord blood and no adverse neonatal effects, as measured by umbilical artery blood gases and neurobehavioral scores. Murray et al 112 reported similar results using the Brazelton Scale and mother-infant interaction during feeding and mothers' perception of their infants.…”

“…The question of duration of epidural anesthesia was investigated by Bader et al, 15 who found that maternal venous and umbilical venous levels of fentanyl and bupivacaine were relatively constant whether the epidural lasted 1 hour or up to 15 hours. Total doses varied between 27 and 200 mg for bupivacaine and 22 to 300 mg for fentanyl.…”

Complete relief of CRPS-associated pain during magnesium infusion in a patient with postpartum preeclampsia

“…Additionally, it is possible that hypermagnesemia potentiated analgesic effects of residual systemic fentanyl. A similar epidural fentanyl regimen has been reported to produce mean maternal plasma concentrations of 0.17 ng/mL, regardless of duration of infusion,8 and presence of plasma fentanyl, with an elimination half-life of more than 190 min, has been shown to persist for a long time after even a single epidural dose 9…”