Thoracic paravertebral blocks in abdominal surgery - a systematic review of randomized controlled trials.

Thoracic paravertebral blocks (TPVBs) have an extensive evidence base as part of a multimodal analgesic strategy for thoracic and breast surgery and have gained popularity with the advent of ultrasound guidance. However, this role is poorly defined in the context of abdominal surgery. We performed a systematic review of randomized controlled trials, to clarify the impact of TPVB on perioperative analgesic outcomes in adult abdominal surgery. We identified 20 published trials involving a total of 1044 patients that met inclusion criteria; however there was significant heterogeneity in terms of type of surgery, TPVB technique, comparator groups and study quality. Pain scores and opioid requirements in the early postoperative period were generally improved when compared with systemic analgesia, but there was insufficient evidence for any definitive conclusions regarding comparison with epidural analgesia or other peripheral block techniques, or the benefit of continuous TPVB techniques. The reported primary block failure rate was 2.8% and the incidence of complications was 1.2% (6/504); there were no instances of pneumothorax. TPVB therefore appears to be a promising analgesic technique for abdominal surgery in terms of efficacy and safety. But further well-designed and adequately powered studies are needed to confirm its utility, particularly with respect to other regional anaesthesia techniques.