Intrathecal opioids versus epidural local anesthetics for labor analgesia: A meta-analysis

Background and Objectives: Some anesthesiologists contend that intrathecal opioid administration has advantages over conventional epidural techniques during labor. Randomized clinical trials comparing analgesia and obstetric outcome using single-injection intrathecal opioids versus epidural local anesthetics suggest that intrathecal opioids provide comparable analgesia with few serious side effects. This meta-analysis compared the analgesic efficacy, side effects, and obstetric outcome of single-injection intrathecal opioid techniques versus epidural local anesthetics in laboring women. Methods: Relevant clinical studies were identified using electronic and manual searches of the literature covering the period from 1989 to 2000. Searches used the following descriptors: intrathecal analgesia, spinal opioids, epidural analgesia, epidural local anesthetics, and analgesia for labor. Data were extracted from 7 randomized clinical trials comparing analgesic measures, incidence of motor block, pruritus, nausea, hypotension, mode of delivery, and/or Apgar scores. Results: Combined test results indicated comparable analgesic efficacy 15 to 20 minutes after injection with single-injection intrathecal opioid administration. Intrathecal opioid injections were associated with a greater incidence of pruritus (odds ratio, 14.01; 99% confidence interval, 6.9 to 28.3), but there was no difference in the incidence of nausea or in the method of delivery. Conclusions: Published studies suggest that intrathecal opioids provide comparable early labor analgesia when compared with epidural local anesthetics. Intrathecal opioid administration results in a greater incidence of pruritus. The choice of technique does not appear to affect the method of delivery.