///2012 Abstract Details
2012 Abstract Details2019-08-02T19:38:42-06:00

Ultra-low versus Higher-Concentration Epidural Local Anesthetic Solutions in Labor: a Meta-Analysis of Outcomes

Abstract Number: T-12
Abstract Type: Original Research

Caitriona Murphy MB BCh BAO, FCARCSI1 ; Pervez Sultan MB BCh, FRCA2; Stephen Halpern MD MSc, FRCPC3; Brendan Carvalho MBBCh, FRCA, MDCH4

Introduction: While epidural analgesia does not increase the cesarean delivery rate compared to non-epidural techniques [1], the effect of epidural analgesia on the incidence of operative vaginal delivery is controversial. Current guidelines suggest that low concentrations of local anesthetics (<0.125% bupivacaine) are preferable to higher concentrations [2]. The purpose of this meta-analysis was to determine whether ultra-low concentration (ULC) infusions of local anesthetics are associated with a lower incidence of assisted vaginal delivery (AVD) than higher concentrations (HC).

Methods: We searched electronic databases (PUBMED,EMBASE, Ovid MEDLINE, CINAHL) and the Cochrane Central Register of Controlled Trials 2nd Quarter 2011 using MeSH terms and text words ropivacaine, bupivacaine, obstetric labor complications, instrumental and cesarean delivery. We included randomized controlled trials of laboring patients that compared ULC (defined as <0.1% epidural bupivacaine or <0.17% ropivacaine) with higher local anesthetic concentrations for maintenance of analgesia. The study quality was graded using the Jadad 5 point scale and allocation blinding[3]. The primary outcome was AVD. The odds ratio (OR) and 95% confidence interval (CI) was calculated using random effects modeling (Review Manager 5.0). An OR <1 favored ULC and a p value <0.05 was considered statistically significant.

Results: 16 studies met our criteria. 5 publications from the COMET study group were presented as one study. There were 1284 patients in the ULC group and 892 patients in the HC group that reported the primary outcome. The median quality score was 2 (range 1 to 5). 6 studies had blinded allocation and 7 studies were not blinded or not clearly outlined. There was a statistically significant reduction in the incidence of assisted vaginal delivery in the ULC group (OR=0.79, 95% CI=0.64-0.98, p=0.03) (Figure). There was no difference in the incidence of cesarean delivery (OR=0.95, 95% CI=0.77-1.18, p=0.65).

Conclusion: The use of ULC of local anesthetics for labor epidural analgesia maintenance reduced the incidence of AVD compared to HC solutions. We therefore recommend the use of ULC epidural analgesia whenever possible to optimize obstetric outcomes.


1. Anim-Somuah et al. Cochrane Database Syst Rev 2011;12:CD 000331

2. ASA Guidelines. Anesthesiology 2007;106:843-863

3. Jadad AR et al. Control Clin Trials 1996;17:1-12

SOAP 2012