Opioid-sparing effects of the thoracic interfascial plane blocks: A meta-analysis of randomized controlled trials

Background: Thoracic interfascial plane blocks and modification (PECS) have recently gained popularity for analgesic potential during breast surgery. We evaluate/consolidate the evidence on opioid-sparing effect of PECS blocks in comparison with conventional intravenous analgesia (IVA) and paravertebral block (PVB). Materials and Methods: Prospective, randomized controlled trials comparing PECS block to conventional IVA or PVB in patients undergoing breast surgery published till June 2017 were searched in the medical database. Comparisons were made for 24-h postoperative morphine consumption and intraoperative fentanyl-equivalent consumption. Results: Final analysis included nine trials (PECS vs. IVA 4 trials and PECS vs. PVB 5 trials). PECS block showed a decreased intraoperative fentanyl consumption over IVA by 49.20 mcg (95% confidence interval [CI] =42.67-55.74) (I² = 98.47%, P < 0.001) and PVB by 15.88 mcg (95% CI = 12.95-18.81) (I² = 95.51%, P < 0.001). Postoperative, 24-h morphine consumption with PECS block was lower than IVA by 7.66 mg (95% CI being 6.23-9.10) (I² = 63.15, P < 0.001) but was higher than PVB group by 1.26 mg (95% CI being 0.91-1.62) (I² = 99.53%, P < 0.001). Two cases of pneumothorax were reported with PVB, and no complication was reported in any other group. Conclusions: Use of PECS block and its modifications with general anesthesia for breast surgery has significant opioid-sparing effect intraoperatively and during the first 24 h after surgery. It also has higher intraoperative opioid-sparing effect when compared to PVB. During the 1^st postoperative day, PVB has slightly more morphine sparing potential that may however be associated with higher complication rates. The present PECS block techniques show marked interstudy variations and need standardization.