Comparative Effectiveness of Preoperative Paravertebral Block for Post-Mastectomy Reconstruction: A Systematic Review of the Literature

Introduction: Paravertebral block (PVB) has emerged as a viable strategy for improving postoperative outcomes in breast surgery; however, it is unclear whether these benefits extend to recipients of post-mastectomy reconstruction (PMR). Methods: A systematic search of the PubMed, EMBASE, Web of Science and Cochrane Library electronic databases was conducted for all studies matching the a priori inclusion criteria (inception to 1 March 2017). Independent assessment by two reviewers, in stages, of the title/abstract and full text was performed. Data relating to study design, patient characteristics, PVB medications and technique, and outcomes, including pain, opioid consumption, length of stay (LOS), postoperative nausea and vomiting (PONV), and PVB-related complications was abstracted. Results: Of the 1243 identified articles, nine met the inclusion criteria, accounting for 936 patients (PVB, n = 518; non-PVB, n = 418) in two randomized controlled trials (RCT) and seven retrospective cohort studies. Of these studies, six described PVB for prosthetic PMR, and three described PVB for autologous PMR. Overall, there is a subtle trend towards improved pain control, less opioid requirement and shorter LOS, while PONV was largely unchanged in patients receiving PVB for PMR. In two studies, technical failure was reported at 7.4 and 10%, although no study reported a PVB-related complication. Study quality varied, and risk of bias in the included studies was high. Heterogeneity precluded a meta-analysis. Conclusions: Although recent reports and RCTs advocate for PVB use in PMR, our review highlights significant heterogeneity and knowledge gaps that must be addressed in order for PVB to become part of the optimal anesthetic protocol in PMR.