The objective is to evaluate if high-dose epidural fentanyl (100 micrograms) is more
effective at providing pain relief during the late first stage (>8 cm cervical dilation)
and second stage of labor until the time of delivery compared to low-dose epidural
fentanyl (20 micrograms). In this study, anesthetic care will be provided to a subject by
an experienced anesthesia provider according to standard hospital care. If the subject
has adequate pain relief from the continuous epidural infusion, then a study investigator
will record the verbal pain score and document any other side effects at hourly intervals
beginning at >8cm cervical dilation, but no additional epidural medications will be
administered. If pain relief becomes inadequate during the late first or second stage of
labor (>8cm cervical dilation) and a manual epidural bolus is required, then the subject
will be randomly assigned to one of two groups (like flipping a coin): one group will
receive lower dose epidural fentanyl (20 micrograms) combined with local anesthetic; and
one group will receive higher-dose epidural fentanyl (100micrograms) combined with the
same amount of local anesthetic. Both doses are used frequently on labor and delivery and
are considered to be safe based on available evidence. If there is not sufficient pain
relief from the epidural medication given, then an experienced anesthesia provider will
assess if another epidural dose may be effective and this additional epidural medication
will be given at the discretion of the anesthesia provider. An experienced anesthesia
provider will be available at all times during the study to assess pain and provide
epidural medications. All patients participating in the study will have their pain scores
assessed every hour as soon as the cervical dilation is noted to be >8cm; at the time of
randomization; and at 10, 20, 30 and 60 minutes after the epidural dose is administered.
The presence of any side-effects such as itching, shivering, nausea, vomiting, low blood
pressure, slow respiratory rate or lower extremity muscle weakness will also be collected
at hourly intervals as soon as the cervical dilation is noted to be >8cm. Subject
satisfaction (1-100 rating scale) with anesthetic care provided will be assessed on
postpartum day # 1 during routine follow-up visit.