What Epidural Opioid Results in the Best Analgesia Outcomes and Fewest Side Effects after Surgery?: a meta-analysis of randomized controlled trials.
Review: The authors have performed a meta-analysis resulting in this investigation of 24 publications comparing epidural opioids used by infusion for at least 24 hours of postoperative analgesia . About 2/3's were studies of catheter congruent epidural placement (16/24) and most (?/24) used a local anesthetic agent combined by infusion with the compared opioid. Half the studies used opioid dosing deemed to be equi-analgesic (12/24) and three quarters (18/24) confirmed catheter placement. Two studies were in pediatric patients. The primary conclusion was that morphine was associated with more nausea and pruritis than fentanyl but analgesia measured by VAS was the same. Ten of the studies compared these two particular opioids. Comparative study of hydromorphone was lacking.
Epidural opioids are widely used for central neuraxial blockade and postoperative analgesia. However, differences in analgesic efficacy and side effect rates among individual opioids remain controversial.
We conducted a random-effects meta-analysis of randomized controlled trials that compared at least 2 continuous epidural infusions for acute postoperative analgesia over at least 24 hours. Individual study data were weighted by the inverse-variance method. Visual analog scale (VAS) pain scores were the primary outcome. Secondary outcomes included opioid side effects, such as pruritus, postoperative nausea and vomiting (PONV), sedation, hypotension, and respiratory depression.
Nineteen of the 24 trials included compared 2 of the following opioids: morphine, fentanyl, or sufentanil. The total subjects studied were 1513. Pooled analysis by type of surgery showed no clinically significant differences in VAS pain scores at any time after surgery. There were more PONV (OR = 1.91; 95% CI, 1.14-3.18; P = 0.014) and perhaps pruritus (OR = 1.64; 95% CI, 0.98-2.76; P = 0.162) with morphine compared to fentanyl. Total opioid consumption differed only in the trials comparing morphine and fentanyl, where patients in the morphine group required 1.2 mg (of morphine equivalent) less (95% CI, 0.27-2.18). Use of analgesic adjuncts was similar for all but 2 studies.
Analgesic outcome, in terms of VAS pain score, was similar between the epidural opioids studied. These similarities in analgesia may reflect the common practices of concurrently using epidural local anesthetics with the opioids and titrating infusion rates according to a patient's pain status. With respect to side effects, the incidence of PONV and possibly pruritus was higher with morphine compared with fentanyl, despite there being similar total opioid consumption between those groups.