Parascapular Sub-Iliocostalis Plane Block: Comparative Description of a Novel Technique for Posterior Rib Fractures.

We describe a new analgesic technique, parascapular sub-iliocostalis plane block (PSIP), for lateral-posterior rib fractures as an alternative to other regional techniques in a high-risk patient who suffered a decompensation of her cardiorespiratory function after posterior chest trauma. We performed a continuous ultrasound-guided left PSIP block in the sub-iliocostalis plane next to the fourth rib to optimize analgesia and minimize complications. The patient had total pain relief with marked improvement in her cardiorespiratory condition. No complications were reported. The efficacy of the PSIP block may potentially depend on different mechanisms of action: (1) direct action in the fracture site by craniocaudal myofascial spread underneath the erector spinae muscle (ESM); (2) spread to deep layers through tissue disruption caused by trauma, to reach the proximal intercostal nerves; (3) further medial spread through deeper layers to the midline to block the posterior and ventral spinal nerves; (4) medial spread below the ESM, to reach the posterior spinal nerves (more reliably than rhomboid intercostal / sub-serratus [RISS] block); and (5) lateral spread in the sub-serratus (SS) plane to reach the lateral cutaneous branches of the intercostal nerves; while avoiding significant negative hemodynamic effects associated with techniques such as the paravertebral block (PVB), erector spinae plane (ESP) block or its variations, or thoracic epidural analgesia (TEA). A comparative comprehensive overview of the regional techniques described for posterior chest trauma is presented, including TEA, PVB, ESP block, retrolaminar block, mid-point to transverse process block, costotransverse foramen block, RISS, and serratus anterior plane (SAP) block.