///2017 Abstract Details
2017 Abstract Details2019-08-02T15:54:53-05:00

Association Between Bolus Rate and Duration of Adequate Labor Analgesia

Abstract Number: BP-05
Abstract Type: Original Research

Elizabeth M S Lange M.D.1 ; Cynthia A Wong MD2; Suman Rao MD3; Wilmer Davila BS4; Paloma Toledo MD, MPH5


Programmed intermittent boluses of local anesthetic have been shown to be superior to continuous infusions for maintenance of labor analgesia. One suggested mechanism is improved spread of the local anesthetic within the epidural space. An in vitro study found that higher programmed intermittent epidural infusion delivery speeds generate higher epidural pressures. The objective of this study was to determine if higher delivery speeds result in a longer duration of adequate analgesia than lower delivery speeds. We hypothesized that a higher-speed bolus would result in a longer duration of adequate analgesia.


Nulliparous women with a singleton pregnancy, admitted to labor and delivery for spontaneous or induced labor, and at a cervical dilation of ≤5cm at request for neuraxial analgesia, were eligible for this double-blind randomized controlled study. Combined spinal-epidural analgesia was initiated with an intrathecal dose of 25mcg fentanyl. The maintenance epidural solution was bupivacaine 0.625 mg/mL with fentanyl 1.95 mcg/mL. Programmed intermittent boluses of 10 mL administered every 60 minutes were given using a CADD-Solis pump, starting 30 minutes after intrathecal injection. Patients in the high-delivery speed group received the timed bolus at a rate of 300 mL/h. The bolus speed in the low-speed group was 100 mL/h. The primary outcome was time to first request for supplemental analgesia.


Patient characteristics were similar in both groups (Table 1). Epidural analgesia was initiated at a similar cervical dilation in both groups. There was no difference in the number of patients that required supplemental analgesia, or in the time to first request for supplemental analgesia between the groups. Mode of delivery, motor block at delivery, and overall satisfaction with labor analgesia was also similar between the two groups.


While there was a trend towards longer duration of adequate analgesia in the higher delivery speed group, there was no difference between the groups. As clinical outcomes were similar between the groups, either bolus delivery speed should be acceptable for clinical care. Future work should determine the optimal bolus volume and timing interval when using programmed intermittent bolus analgesia.

SOAP 2017