Dilute Versus Concentrated Epidural Bupivacaine in Labor

Analgesia Requirement and Maternal Satisfaction Following Epidural PCA in Nulliparous Labor: the Effect of a Four-Fold Change in Local Anesthetic Concentration.

This study studies labor epidural analgesia and compares dilute (0.0625%) with concentrated (0.25%) bupivacaine.

We hypothesize that patients randomize to receive the concentrated drug will require more drug, will have a more profound motor block, will be more likely to require instrumental delivery and will be less satisfied than those receiving dilute epidural drugs.

This study examines the effect of two different local anesthetic concentrations used for epidural analgesia in labor. Patients are randomized to receive epidural bupivacaine, either as a concentrated (0.25%), or a dilute (0.0625%) solution, both administered by patient-controlled epidural analgesia (PCEA).

Inclusion Criteria:

• nulliparity, active spontaneous labor, cervical dilatation greater than 2cm and less than 5 cm, request for epidural analgesia, age between 18 to 40, American Society of Anesthesiologists (ASA) physical status I or II, body weight less than 110kg, gestational age greater than 36 completed weeks, singelton pregnancy and vertex presentation

Exclusion Criteria:

• narcotic administration in the previous 3 hours, non-reassuring fetal heart rate tracing at any stage in labor prior to enrollment, previous uterine surgery, pre-eclampsia and the inability to adequately understand the consent process.