Epidural Local Anesthetics Versus Opioid-Based Analgesic Regimens for Postoperative Gastrointestinal Paralysis, Vomiting, and Pain After Abdominal Surgery

A Cochrane Review

Joanne Guay, MD; Mina Nishimori, MD; Sandra L. Kopp, MD


Anesth Analg. 2016;123(6):1591-1602. 

In This Article


We included parallel randomized controlled trials (RCTs) in which an epidural containing a local anesthetic (with or without the addition of opioids) was added to general anesthesia and continued or not for postoperative analgesia or used for postoperative analgesia in 1 group, and where this group was compared with systemic or epidural opioid-based regimens in another group. We excluded quasi-randomized trials. We applied no language or publication status restriction. Those RCTs included adults (≥16 years old accepted) participants undergoing any abdominal surgery (open or laparoscopic) under general anesthesia. We excluded trials performed on children, trials performed outside the perioperative period (chronic pain, labor analgesia) and trials performed with participants undergoing surgery on other surgical sites (not abdominal surgery). Because some substances are not universally accepted as safe for injection in the epidural space, we did not retain in the analysis a trial (or subgroup) where anything else than an opioid or a local anesthetic or epinephrine was injected in the epidural space. We evaluated the differences between the treatment group and the control group on the following outcomes:

Primary Outcomes

  1. Postoperative paralytic ileus as measured by first passage of flatus.

Secondary Outcomes

  1. Postoperative paralytic ileus as measured by first passage of feces (stool).

  2. Pain scores (any ascending scale) on movement at 24 hours.

  3. Incidence of postoperative vomiting: number of participants who had experienced vomiting on day 1.

  4. Gastrointestinal anastomotic leak.

  5. Length of hospital stay.

  6. Hospital costs.

We searched the following electronic databases to identify potential studies: Cochrane Central Register of Controlled Trials (CENTRAL; 2014 Issue 12), MEDLINE (OVID) 1950 to December 2014; and EMBASE (OVID) 1974 to December 2014 (Supplemental Digital Content, Supplemental Appendix 1, https://links.lww.com/AA/B527). Two review authors (J.G. and Dr. Dat Nut Nguyen [D.N.N., left the review before its completion]) scanned the titles and abstracts of all reports identified by electronic searching, retrieved full texts of those articles and independently extracted data (J.G., D.N.N. or M.N.). We resolved disagreements by discussion, the help of a third author was never required. The methodological quality of the selected studies was evaluated with the Cochrane tool by 2 authors (J.G., D.N.N. or M.N.) from the report with no assumption. We rated as unclear an element for which there was not enough information contained in the report to allow us to make a clear judgment. We extracted events and total numbers of participants in each group for dichotomous data when available. We extracted mean, standard deviation (SD) and number of participants in each group for continuous data when available. If results were unavailable in our favored format or provided on different scales, we extracted data as P values and number of participants for each group. We also extracted sites and dates of data collection (for exclusion of duplicate publication) and factors required for heterogeneity exploration (see assessment of heterogeneity). We contacted authors for additional information when we did not have enough information from the published articles to extract the data. We made no imputation. We considered clinical heterogeneity before pooling results and examined statistical heterogeneity before carrying out any metaanalysis. We quantified statistical heterogeneity using the I2 statistic. We qualified the amount as low (< 25%), moderate (50%) or high (≥ 75%) depending of the value obtained for the I2 statistic.[8] We assessed publication bias with a funnel plot followed by Duval and Tweedie's trim and fill technique. We analyzed data with RevMan (https://ims.cochrane.org/revman/about-revman-5) and Comprehensive Meta Analysis Version 2.2.044 (www.Meta-Analysis.com) with fixed (I2 < 25%) or random-effects models (I2 > 25%). For standardized mean differences (SMDs) we considered 0.8 as the cutoff limit for a large effect.[9] For clinical equivalents, we multiplied the SMD by the SD of a study at low risk of bias and where a typical SD on a clinical scale was provided.[10] For results where the intervention produced an effect, we calculated the number needed-to-treat for additional beneficial outcome or the number needed-to-treat for additional harm based on the odds ratio. When results were negative, we also calculated the optimal information size in order to make sure that there were enough participants included in the retained studies to justify a conclusion on the absence of effect.[11] We explored any amount of heterogeneity >25% with the Egger's regression intercept (to eliminate a small-study effect), sensitivity analysis, sub-grouping or meta-regression as appropriate. A priori factors for heterogeneity were the: level of the epidural (thoracic versus lumbar); type of drug used (local anesthetic alone [concentration in lidocaine equivalent potency calculated as follows: lidocaine = 1, bupivacaine = 4, chloroprocaine = 1.5, dibucaine = 4, etidocaine = 4, levobupivacaine = 3.9, mepivacaine = 0.8, prilocaine = 0.9, procaine = 0.5, ropivacaine = 3 and tetracaine = 4[12]]) versus local anesthetic plus opioid (and type of opioid); timing (pre- versus post-surgical incision) and duration of administration (intraoperative only, <48 versus ≥ to 48 hours); site of surgery (bowel surgery, gynecologic, urologic or vascular); type of surgery (open versus laparoscopic); mean group age, American Society of Anesthesiologists physical status; and substance used and route of administration of analgesia in the control group (intravenous [with or without use of a patient controlled analgesia device] versus epidural [with or without the use of a patient controlled analgesia device] versus other routes). Sensitivity analysis (defined as excluding a study on the risk of bias or because it appeared as outlier on a forest plot) were performed. The quality of the body of evidence was judged according to the system developed by the GRADE working group[13] and presented in a "Summary of findings" table for the all our outcomes.