///2009 Abstract Details
2009 Abstract Details2019-08-03T15:55:31-06:00

A randomized trial of the effect of manipulation of the programmed intermittent bolus volume and time interval on the extent of sensory blockade during epidural labor analgesia

Abstract Number: 167
Abstract Type: Original Research

Cynthia A Wong M.D.1 ; Amy I Lee M.D.2; Renee C Gora B.S., R.N.3; Mary J Ebarvia R.N.4; Robert J McCarthy PharmD.5

Introduction: Programmed intermittent epidural bolus (PIEB) administration of local anesthetic/opioid compared to continuous infusion decreases the total bupivacaine dose, need for manual boluses, and increases patient satisfaction during maintenance of epidural labor analgesia(1,2). The mechanism by which PIEB results in lower anesthetic consumption and requirement for supplemental analgesia is not known, but may involve better distribution of anesthetic solution within the epidural space (3,4). We hypothesized that a large volume administered every 60 min compared to smaller volumes administered every 30- or 15 min as PIEB would increase the extent and density of sensory blockade.

Methods: Nulliparas in spontaneous labor who requested analgesia at cervical dilation between 2- and 5-cm gave informed consent to participate in this IRB-approved randomized, double-blind trial. After initiation of CSE analgesia with intrathecal (IT) bupivacaine 1.25 mg/fentanyl 15 g and epidural lidocaine 45 mg/epinephrine 15 g, subjects were randomized to one of three groups to receive PIEB maintenance analgesia: Group 60 (10 mL q60 min), Group 30 (5 mL q30 min), or Group 15 (2.5 mL q15 min). The maintenance solution was bupivacaine 0.625 mg/mL with fentanyl 2 g/mL. Patients were allowed to self-administer 5 mL boluses every 10 min, and ask for supplemental analgesia if analgesia was inadequate. The extent of sensory blockade to cold( ice) was measured at 15 min and 3 h after the IT injection. Sensory thresholds (g) were determined at the T12, T10, T7, and T4 dermatomes using von Frye filaments before and 3 h after the IT injection. Data were compared between groups with the Kruskal-Wallis test. P < 0.05 was significant.

Results: There was no difference among groups in the sensory threshold at baseline. Pressure thresholds were increased at 3 h in all groups, but did not differ among groups (Table). Cephalad sensory levels to cold did not differ among groups at 15 min and 3 h post-IT injection.

Discussion: Possible explanations for this finding include 1) lack of association between PIEB and extent of sensory blockade, 2) inadequate sensitivity of measurement of sensory blockade, or 3) no difference in characteristics of epidural analgesia in women who receive large volume /interval vs. small volume/interval PIEB.


1.Anesth Analg 2006;102:904-9

2.Anesth Analg 2007;104:673-8

3.Anesthesiology 2005;103:126-9

4.Reg Anesth Pain Med 2002;27:150-6

SOAP 2009