Improving Analgesic Efficacy and Safety of Thoracic Paravertebral Block for Breast Surgery: A Mixed-Effects Meta-Analysis.

BACKGROUND While most trials of thoracic paravertebral nerve blocks (TPVB) for breast surgery show benefit, their effect on postoperative pain intensity, opioid consumption, and prevention of chronic postsurgical pain varies substantially across studies. Variability may result from use of different drugs and techniques. OBJECTIVES To examine the use of TPVB in breast surgery, and to determine which method(s) provide optimal efficacy and safety. STUDY DESIGN Mixed-Effects Meta-Analysis. METHODS We conducted a systematic review of randomized trials comparing TPVB to no intervention using random-effects models. To evaluate the contributions of various techniques, clinical approaches were included as moderators in mixed-effects models. RESULTS A total of 24 randomized controlled trials (RCTs) with 1,822 patients were included. Use of TPVB decreased postoperative pain scores at rest and movement at the first 2, 24, 48, and 72 hours. TPVB modestly decreased intraoperative and postoperative opioid consumption, reduced nausea and vomiting, and shortened hospitalization, but to a probably clinically irrelevant degree. Blocks also appeared to reduce the incidence of chronic postsurgical pain at 6 months. Adding fentanyl to the TPVB improved pain at rest (at 24, 48, and 72 hours) and movement (at 24 and 72 hours). Multilevel blocks provided better postoperative pain control, but only during movement (at 2, 48, and 72 hours). Fewer procedural complications (especially hypotension, epidural spread, and Horner's syndrome) occurred when anatomical landmarks were supplemented with ultrasound guidance. LIMITATIONS The number of studies available was limited in the meta-analytic model of incidence of chronic post-surgical pain. CONCLUSION TPVB reduces postoperative pain and opioid consumption, and has a limited beneficial effect on the quality of recovery. From all the techniques that were evaluated, only the addition of fentanyl, and performing multilevel blocks were associated with improved acute analgesia. TPVB may reduce chronic postsurgical pain at 6 months.