Continuous Extradural Infusion of 0.0625% or 0.125% Bupivacaine for Pain Relief in Primigravid Labour

Abstract

The efficacy of an extradural infusion of 0.0625% or 0.125% bupivacaine was studied in 98 primigravid mothers in active labour. No special measures were taken to posture the mother (except to avoid aorto-caval compression). The study regimen included a control group (no infusion) receiving intermittent top-ups (0.25%. bupivacaine 8-10 ml), two groups receiving bupivacaine 6.25 mg h-1 infusion in different concentrations (0.0625% and 0.125%), a fourth group receiving 0.125% bupivacaine 12.5 mg h-1 infusion, and a fifth group receiving 0.125% bupivacaine 18.75 mg h-1 infusion. The optimum infusion rate was 0.125% bupivacaine 10 ml h-1, at which 69% of primigravid mothers required none or only one "top-up" of 0.25% bupivacaine 8-10 ml during a mean duration of 7.1 h labour. In the group who had no extradural infusion, only 32% of mothers managed with one or no top-up. The median interval between top-ups was increased from 145 min in the no infusion group to 245 min in those mothers receiving 0.125% bupivacaine 10 ml h-1 by infusion. Increasing the rate of infusion to 15 ml h-1 did not improve the results. Spread of local anaesthetic to higher levels was limited (less than T5) so that testing sensory loss at the T5-6 level at 2-hourly intervals should detect accidental spinal blockade resulting from inadvertent intrathecal infusion.

Comparison of Plasma Bupivacaine Concentrations During Continuous Extradural Infusion for Labour

“…The continuous infusion of local anaesthetic for extradural analgesia uses more local anaesthetic than the intermittent top-up technique [7,8]. As plasma concentrations at delivery were not significantly greater, these findings suggest differences in drug uptake and distribution between the two types of administration [7,9].…”

A Comparison of Analgesia and Foetal Outcome in Term Parturients With and Without Low Dose Combined Spinal Epidural Labour Analgesia

“…8 Li et al studied the efficacy of bupivacaine by reducing the concentration from 0.25% down to 0.0625% as bolus. 9 Purdy et al compared 0.5%, 0.375% and 0.25% bupivacaine given as bolus doses. 10 They observed that by reducing the concentration, the quality of analgesia was not affected, and lower concentrations of local anaesthetics minimized or prevented the motor block.…”

COMPARATIVE CLINICAL STUDY BETWEEN EPIDURAL AND COMBINED SPINAL EPIDURAL ANALGESIA ON LABOUR WITH 0.125% BUPIVACAINE AND 20μG FENTANYL

“…Li et al studied the efficacy of bupivacaine by reducing the concentration from 0.25% upto 0.0625% as bolus. 11 Purdy et al compared 0.5%, 0.375%, 0.25% bupivacaine given as bolus. 12 They observed that by reducing the concentration, quality of analgesia did not differ.…”