The role of serratus anterior plane and pectoral nerves blocks in cardiac surgery, thoracic surgery and trauma: a qualitative systematic review.

Serratus anterior plane and pectoral nerves blocks are recently described alternatives to established regional anaesthesia techniques in cardiac surgery, thoracic surgery and trauma. We performed a systematic review to establish the current state of evidence for the analgesic role of these fascial plane blocks in these clinical settings. We identified relevant studies by searching multiple databases and trial registries from inception to June 2019. Study heterogeneity prevented meta-analysis and studies were instead qualitatively summarised and stratified by type of surgery and comparator. We identified 51 studies: nine randomised control trials; 13 cohort studies; 19 case series; and 10 case reports. The majority of randomised controlled trials studied the serratus anterior plane block in thoracotomy or video-assisted thoracoscopic surgery, with only two investigating pectoral nerves blocks. The evidence in thoracic trauma comprised only case series and reports. Results indicate that single-injection serratus anterior plane and the pectoral nerves blocks reduce pain scores and opioid consumption compared with systemic analgesia alone in cardiothoracic surgery, cardiac-related interventional procedures and chest trauma for approximately 6-12 h. The duration of action appears longer than intercostal nerve blocks but may be shorter than thoracic paravertebral blockade. Block duration may be prolonged by a continuous catheter technique with potentially similar results to thoracic epidural analgesia. There were no reported complications and the risk of haemodynamic instability appears to be low. The current evidence, though limited, supports the efficacy and safety of serratus anterior plane and the pectoral nerves blocks as analgesic options in cardiothoracic surgery.