Ultrasound-guided fascial plane blocks of the chest wall: a state-of-the-art review

Ultrasound-guided fascial plane blocks of the chest wall are increasingly popular alternatives to established techniques such as thoracic epidural or paravertebral blockade, as they are simple to perform and have an appealing safety profile. Many different techniques have been described, which can be broadly categorised into anteromedial, anterolateral and posterior chest wall blocks. Understanding the relevant clinical anatomy is critical not only for block performance, but also to match block techniques appropriately with surgical procedures. The sensory innervation of tissues deep to the skin (e.g. muscles, ligaments and bone) can be overlooked, but is often a significant source of pain. The primary mechanism of action for these blocks is a conduction blockade of sensory afferents travelling in the targeted fascial planes, as well as of peripheral nociceptors in the surrounding tissues. A systemic action of absorbed local anaesthetic is plausible but unlikely to be a major contributor. The current evidence for their clinical applications indicates that certain chest wall techniques provide significant benefit in breast and thoracic surgery, similar to that provided by thoracic paravertebral blockade. Their role in trauma and cardiac surgery is evolving and holds great potential. Further avenues of research into these versatile techniques include: optimal local anaesthetic dosing strategies; high-quality randomised controlled trials focusing on patient-centred outcomes beyond acute pain; and comparative studies to determine which of the myriad blocks currently on offer should be core competencies in anaesthetic practice.