The opioid sparing effect of erector spinae plane block for various surgeries: A meta-Analysis of randomized-controlled trials

INTRODUCTION: The erector spinae plane block (ESPB) is a newer fascial plane block which has been broadly applied for postoperative analgesia after various surgeries, but the effectiveness in these populations is not well established. EVIDENCE ACQUISITION: A systematic database search was conducted in PubMed, PMC, Embase, and Scopus for randomized controlled trials (RCTs) comparing ESPB with control, placebo, or other blocks. The primary outcome was intravenous opioid consumption in milligram morphine equivalents 24 h after surgery. Standardized mean differences (SMDs) with 95% confidence intervals (CI) were calculated using a random-effects model. EVIDENCE SYNTHESIS: A total of 29 RCTs were included. An analysis was conducted by subgroups differentiated by surgery type, no block vs. ESPB, and other blocks vs. ESPB. ESPB was effective in reducing opioid consumption against no block for breast surgery (SMD-1.13; 95% CI), thoracic surgery (SMD-3.00; 95% CI), and vertebral surgery (SMD-1.78; 95% CI). ESPB was effective against alternative blocks for breast surgery (vs. paravertebral, SMD-1.07; 95% CI) and abdominal surgery (SMD-1.77; 95% CI). ESPB showed moderate effect in thoracic surgery against paravertebral (SMD 0.58; 95% CI) and against no block in abdominal surgery (SMD 0.80; 95% CI). In only one case did ESPB perform worse than another block: vs. PECS block for breast surgery (SMD 1.66; 95% CI). CONCLUSIONS: ESPB may be a useful addition to the multimodal analgesic regimen for a variety of surgeries especially when the alternative is no block. Unanswered questions include determining of the mechanism of action, refining of the EPSB technique, and establishing recommended local anesthetic dose and volume.