Effects of Bupivacaine Induced Motor Blockade During the Second Stage of Labor

Summary

The aim of this study is to measure the effects of bupivacaine administered via epidural catheters on indices of motor blockade ascertained during the second stage of labor. This is a randomized, double-blind, controlled trial designed to address the primary research question: Does bupivacaine lengthen the second stage of labor? The secondary research question is: Is there other evidence of motor blockade attributable to bupivacaine during the second stage of labor?

The investigators know from prior studies that the length of the second stage in nulliparous women delivered at Parkland Hospital without epidural analgesia is 28 minutes. The investigators hypothesize in this now proposed study that epidural analgesia with bupivacaine will significantly increase this baseline from 28 minutes to 37 minutes or more (a 33% increase) thus implicating motor blockade. Baseline data for the Bromage and Breen scores during the second stage as well as the uterine contractility data are not available as these indices of motor blockade have not here-to-fore been studied in this context.

Currently at Parkland Hospital, 82% of nulliparous women undergoing induction of labor at term receive continuous epidural infusions with bupivacaine during the first and second stages of labor. Such women will be identified when admitted for scheduled inductions at Parkland. After informed consent is obtained standard management of labor induction will be provided. Those consented women reaching 8 cm cervical dilation will be randomized. Group I will receive bupivacaine plus fentanyl via epidural catheter during the second stage (i.e. 10 cm dilation) and Group II will receive only fentanyl infusion via epidural catheter (see study procedure below). Both the patient and the caregiver will be blinded as to whether the patient is in the bupivacaine plus fentanyl arm or the fentanyl only arm. To detect a 33% increase (from 28 minutes to 37 minutes) in the primary outcome the investigators need a total of 310 women enrolled in the study (or 155 per arm). Assuming a 30% consent rate and given that approximately 1000 women meet the inclusion criteria each year at Parkland, the investigators project that this study could be completed in 12 months.

Conditions

• Pregnancy

Interventions

DRUG

Epidural Bupivacaine plus fentanyl

The subjects will receive 0.125% bupivacaine with fentanyl 2 mcg/mL at a rate of 10 mL/hr.

DRUG

Epidural fentanyl

The subjects will receive epidural fentanyl 10 mcg/mL with the rate of 10mL/hr.

Sponsors & Collaborators

• University of Texas Southwestern Medical Center

  lead OTHER

Principal Investigators

• Kenneth Leveno, MD · UT Southwestern Medical Center

• Lisa Moseley · UT Southwestern Medical Center

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

16 Years

Max Age

44 Years

Sex

FEMALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2009-09-30

Primary Completion

2012-07-31

Completion

2013-07-31

Countries

• United States

Study Locations