Optimal Bupivacaine Dose for Initiation of Labor Epidural Techniques

The primary objective of our study is to use a biased coin up-down allocation methodology to estimate the dose of bupivacaine required to achieve initial effective comfort in 90% of patients (ED90) via the epidural (DPE or EPL) technique in women undergoing labor induction or augmentation; we hypothesize that we will be able to determine the ED90 of bupivacaine for each technique with adequate precision to inform the optimal doses.

Inclusion criteria

• Parturient with no major co-morbidities
• Singleton, vertex gestation at term (37-42 weeks)
• Less than or equal to 5 cm dilation
• Desire to receive epidural labor analgesia
• Numerical Rating Scale greater or equal to 5 (NRS 0-10, where 0 = no pain, and 10 = worst pain imaginable), at time of epidural labor analgesia request.

Exclusion criteria

• Current or historical evidence of clinically significant disease or condition, including diseases of pregnancy (i.e preeclampsia, gestational diabetes)
• Any contraindication to the administration of an epidural technique
• History of hypersensitivity or idiosyncratic reaction to an amide local anesthetic agent
• Current or historical evidence of a disease which may result in the risk of a cesarean delivery (i.e. history of uterine rupture). NB: Exception-trial of labor after cesarean delivery (TOLAC) will be eligible.
• Evidence of anticipated fetal anomalies