Effect of intrathecal morphine compared with truncal nerve blocks on postoperative analgesia in adults : A meta-analysis of randomized controlled trials.

BACKGROUND

Balancing effective postoperative analgesia with reduced opioid use is crucial in the context of the opioid crisis.

OBJECTIVE

This meta-analysis compares intrathecal morphine (ITM) and truncal nerve blocks (TNBs) to address this challenge.

METHODS

Randomized controlled trials (RCTs) comparing ITM with TNBs were included. Databases searched included CENTRAL, Embase, PubMed, Scopus and Web of Science. Primary outcomes were total opioid consumption within 24 h postoperatively, with secondary outcomes including 48‑h opioid use, pain intensity and postoperative nausea and vomiting (PONV). Effect sizes were estimated using a random effects model with mean difference (MD), standardized mean difference (SMD), or relative risk (RR) and 95% confidence intervals (CIs).

RESULTS

In total, 13 RCTs involving 834 participants were included. The use of ITM significantly reduced opioid consumption at 24 h (SMD: -1.27, 95% CI -2.32, -0.21, P = 0.0185) and 48 h (SMD: -1.01, 95% CI -1.89, -0.13, P = 0.0248) and also lowered resting pain scores at 12 h (MD: -1.05, 95% CI -1.74, -0.36, P = 0.0029) and 24 h (MD: -0.62, 95% CI -1.07, -0.18, P = 0.0062) postoperatively. For dynamic pain, ITM was more effective than TNB at 12 h (MD: -1.33, 95% CI -2.09, -0.57, P = 0.0006) and 24 h (MD: -0.59, 95% CI -1.05, -0.13, P = 0.0128); however, ITM was associated with a higher incidence of PONV (RR: 3.26, 95% CI 1.55, 6.83, P = 0.0018).

CONCLUSION

In comparison to TNBs the use of ITM in relatively high dosages (5-10 μg/kg) provides statistically superior analgesia and reduces opioid use within 24 h postoperatively but its association with increased PONV warrants cautious interpretation and further study.