Evidence-based Practice and Quality Improvement
Background and Goal of Study: Thoracic paravertebral blocks are performed for unilateral postoperative analgesia in breast surgery since 1995. Aim of the present quantitative systematic review was to assess efficacy and possible adverse effects of paravertebral blocks alone or in combination with general anaesthesia compared with other analgesic treatments in women undergoing breast surgery.
Materials and Methods: Included were all randomised controlled trials investigating the efficacy and safety of paravertebral blocks in comparison to other analgesic and anaesthetic strategies for women undergoing breast surgery. The systematic search, data extraction, critical appraisal and pooled analysis were performed according to the PRISMA statement. Relative risk (RR), mean difference (MD) and the consecutive 95% confidence intervals (CI) were calculated using the Revman® as statistical software.
Results and Discussion: Fourteen randomised controlled trials (published between 1999–2009) including 867 patients met the inclusion criteria. There was a significant difference in severe postoperative pain scores between paravertebral blocks alone and general anaesthesia at <2h (MD: -2.68; 95% CI: -3.33 - -2.02; P < 0.0001), 2–24h (MD: -2.34; 95% CI: -3.38 - -1.30; P < 0.0001) and 24–48h (MD: -1.62; 95% CI: -3.09 - 0.16; P < 0.00001) after surgery. Similarly, lower pain scores were observed for combined paravertebral blocks with general anesthesia compared to general anaesthesia alone for <2h (MD: -1.32; 95% CI: -1.75 - -0.9; P < 0.0001), 2–24h (MD: -1.90; 95% CI: -2.28 - -1.52; P < 0.00001), 24–48h (MD: -1.80; 95% CI: -2.92 - 0.68; P = 0.002) after surgery. Furthermore, women undergoing breast surgery with a paravertebral block alone required postoperatively a lower total amount of systemic morphine at 0–24h (MD: -3.59; 95% CI: -6.28 - -0.89; P = 0.009). The RR for adverse events like nerval damage, transient horner syndrome, vascular pucture or pneumothrax following paravertebral block were very low.
Conclusion(s): There is considerable evidence that paravertebral blocks in addition to a general anaesthesia or alone may provide a better postoperative pain control with little adverse effects compared to other analgesic treatment strategies in women undergoing breast surgery. However, these results were limited by clinical heterogeneity due to the application of different surgical techniques and the use of diverse types and doses of local anaesthetics.