Efficacy and safety of paravertebral blocks in breast surgery: a meta-analysis of randomized controlled trials

Thoracic paravertebral blocks (PVBs) are successfully performed for pain management after breast surgery. The aim of the present quantitative systematic review was to assess the efficacy and adverse events of PVB in women undergoing breast surgery. The systematic search, data extraction, critical appraisal, and pooled analysis were performed according to the PRISMA statement. The relative risk (RR), mean difference (MD), and their corresponding 95% confidence intervals (CIs) were calculated using the RevMan((R)) statistical software for dichotomous and continuous outcomes, respectively. Pain scores were converted to a scale ranging from 0 (no pain) to 10 (worst pain). Fifteen randomized controlled trials (published between 1999 and 2009) including 877 patients met the inclusion criteria. There was a significant difference in worst postoperative pain scores between PVB and general anaesthesia (GA) at < 2 h (MD: -2.68; 95% CI: -3.33 to -2.02; P < 0.00001), 2-24 h (MD: -2.34; 95% CI: -2.42 to -1.12; P < 0.00001), and 24-48 h (MD: -1.75; 95% CI: -3.19 to 0.31; P=0.02). Accordingly, lower pain scores were observed for combined PVB with GA compared with GA alone for < 2 h (MD: -1.87; 95% CI: -2.53 to -1.21; P < 0.00001), 2-24 h (MD: -2.21; 95% CI: -3.07 to -1.35; P < 0.00001), and 24-48 h (MD: -1.80; 95% CI: -2.92 to 0.68; P=0.002). The RR for the reported adverse events (e.g. pneumothorax) was low. There is considerable evidence that PVB in addition to GA or alone provide a better postoperative pain control with little adverse effects compared with other analgesic treatment strategies.