Analgaesic efficacy of single-injection serratus anterior plane block for breast surgery: A systematic review, meta-analysis and trial sequential analysis of randomised controlled trials

There is conflicting evidence regarding the analgaesic efficacy of single-shot serratus anterior plane block (SAP) for breast surgery. This meta-analysis aimed to evaluate the analgaesic efficacy of SAP compared with non-block care (NBC) and other regional blocks, i.e. paravertebral block (PVB) and modified pectoral nerve block (PECS block) for breast surgery. PubMed, Embase, Scopus, the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov were searched. We included randomized controlled trials reporting the use of the SAP block in adult breast surgery. The primary outcome was postoperative oral morphine equivalent (OME) consumption for up to 24 hours. Random-effects models were used to pool results and mean difference (MD), and odds ratio (OR) was calculated for continuous and dichotomous outcomes, respectively. GRADE guidelines were used to evaluate the strength of evidence, and trial sequential analysis (TSA) was performed to provide certainty to the conclusion. Twenty-four trials enrolling 1789 patients were included. Moderate strength evidence suggested that SAP provided a significant reduction in 24-hour OME compared with NBC [MD - 24.9 mg (95% CI - 41.54, -8.25; P < 0.001, I 2 = 99.68%)]. TSA ruled out the possibility of false-positive results. Subgroup analysis for the SAP demonstrated that the superficial plane approach was more effective in reducing opioid consumption than the deep approach. The odds of developing PONV were significantly lower in SAP compared to NBC. Compared with PVB and PECS, SAP block was not statistically different for 24-hour OME and time to first rescue analgaesia. Single-shot SAP reduced opioid consumption, prolonged analgaesia duration, lowered pain scores, and decreased the incidence of PONV compared to NBC. There was no statistically significant difference in the studied endpoints between SAP, PVB, and PECS blocks.