Association Between Bolus Rate and Duration of Adequate Labor Analgesia

Cervical dilation will be confirmed by a member of the obstetric team prior to epidural
catheter placement as is routinely done at our institution. A baseline pain visual analog
scale (VAS) score will be obtained using a 100-mm unmarked line with the end points labeled
"no pain" and "worst pain imaginable."

Labor analgesia will be initiated using CSE analgesia with 25 mcg of intrathecal fentanyl.
An epidural test dose will be performed as routine (1.5% lidocaine with epinephrine 1:200, 3
mL).

Labor analgesia will be maintained using timed-intermittent boluses of local anesthetic with
PCEA using the CADD-Solis pump (Smiths Medical). An unblinded anesthesia research nurse will
program the epidural pump and initiate the maintenance of labor analgesia.

Fifteen minutes following the intrathecal dose, a VAS score and a sensory level of analgesia
will be obtained. The following information will be obtained hourly until complete cervical
dilation (10 cm): VAS pain score, sensory level, a modified Bromage score (0 - no motor
paralysis; 1 - inability to raise extended leg, but able to move knee and foot; 2 -
inability to raise extended leg and to move knee, but able to move foot; 3 - inability to
raise extended leg or to move knee and foot).

The time to the first request for supplemental analgesia will be recorded on the study data
sheet. The time, type and volume of local anesthetic used, and VAS scores before and 15
minutes after the redose will be recorded.

All other clinical management will be as per routine, and study participation will not
interfere with anesthetic or obstetric care. Anesthesiologists will manage breakthrough pain
in the usual manner (assessment of stage of labor and extend/density of neuraxial blockade,
followed by the appropriate maneuver to reestablish adequate analgesia).

Following delivery, the patient will be asked to give one final VAS score and her overall
satisfaction with labor using a 100 mm unmarked line. Mode of delivery, as well as the
duration of the 1st and 2nd stage of labor will be recorded by study personnel.

Patient Controlled Epidural Analgesia (PCEA) pump utilization data will be downloaded from
epidural pumps after delivery. This will include the time to first PCEA request, the number
of PCEA demands, the number of times that PCEA boluses were delivered, the total amount of
local anesthetic consumed.

Inclusion Criteria:

- Nulliparous parturients who presents to the labor and delivery unit for an induction
of labor or who are in spontaneous labor, and request neuraxial labor analgesia at <4
cm cervical dilation are eligible to participate.

Exclusion Criteria:

- Patients who are not eligible to receive a combined spinal epidural (CSE) technique
with 25 mcg of intrathecal fentanyl, non-English speaking, who experience failed CSE
analgesia, need to have the epidural catheter replaced during labor, or who deliver
within 90 minutes of initiation of labor analgesia will be excluded from the study.