Erector Spinae Plane Block vs Paravertebral Block for Pain Management in Fractured Ribs

Rib fractures occur most commonly because of blunt thoracic trauma and occur in up to 12% of all trauma patients. Rib fractures themselves pose a significant healthcare burden with its associated morbidity, long term disability, and mortality. Pulmonary morbidity is increased in these patients as a result of diminished gas exchange from fracture induced pulmonary injury and from inadequate analgesia compromising both ventilation and pulmonary mechanics. Various factors affect outcome and mortality after rib fractures. These include the number of ribs fractured, preexisting comorbidities, advanced age, and level of associated pain. Of these, pain is a significant modifiable factor.

Adequate analgesia is paramount in enhancing pulmonary hygiene aimed at preventing atelectasis and pneumonia. Systemic analgesia is usually sufficient in younger patients with fewer undisplaced fractures without a flail segment. Regional techniques are particularly useful in elderly patients (>65 years of age), patients with multiple rib fractures (MRFs), and in patients with severe pain or compromised pulmonary function. Conventional regional techniques used to manage rib fractures include epidural analgesia, paravertebral block (PVB), intercostal, and intrapleural block.

In 2010 Truitt et al. introduced a novel technique whereby local anesthetic (LA) infiltration superficial to the posterior ribs via tunneled catheters successfully controlled rib fracture pain. Since then, multiple thoracic RA (Regional Anesthesia) techniques have been developed that use ultrasound-guided (USG) LA (local anesthetic) injections into fascial planes from the thoracic spinal lamina to the sternum to anesthetize various regions of the thorax.

Some of the conventional regional techniques, particularly epidural analgesia and PVB, may not be feasible in the presence of anticoagulation, multisystem trauma, or in patients unable to be optimally positioned. Recently, several ultrasound-guided (USG) myofascial plane blocks (both single injection and continuous catheter techniques) have been described (e.g. The serratus anterior plane (SAP) block and the erector spinae plane (ESP) block) , which offer the advantages of being less invasive technique and provide adequate analgesia after rib fractures.

ESP block is a novel myofascial plane block recently introduced into clinical practice. It has been successfully utilized in the management of pain after both rib fractures and surgery of the abdomen and thorax, and in the management of chronic thoracic pain. In contrast to the SAP block, the ESP block has the ability to provide analgesia to both the anterior and posterior hemithorax, making it particularly useful in the management of pain after extensive thoracic surgery or trauma (anterior, lateral, and posterior chest wall). Innervation of the ribs and adjoining tissue is primarily through thoracic spinal nerves. After emerging from the spinal cord and traversing through the intervertebral foramina, the thoracic spinal nerves split into ventral and dorsal rami. The ventral rami continue as intercostal nerves innervating the lateral and anterior chest wall, whereas the dorsal rami innervate the posterior chest wall after exiting the paravertebral space.

The ESP block is directed at the erector spinae myofascial plane, which is located on the posterior chest wall between the anterior surface of the erector spinae muscle and oriented cephalocaudally to the posterior surface of the spinal transverse process. Local anaesthetic injected in this plane can block the dorsal rami as they traverse the erector spinae plane, producing anesthesia to the posterior hemithorax. Local anaesthetic also spreads anteriorly and cephalocaudally in the erector spinae plane. Ventral rami and intercostal nerves are blocked by anterior spread, providing analgesia to ribs and periosteum as well as large cutaneous areas of the lateral and anterior chest wall (by blockade of lateral and anterior branches of the intercostal nerves). Cephalocaudal spread provides anesthesia to at least three segments above and four segments below the injection site; a single injection can result in extensive thoracic anesthesia.

PVB has been shown to be as effective as epidural analgesia in managing multiple rib fractures (MRFs). A recent randomized trial has shown that PVB is superior to intravenous patient-controlled analgesia (IVPCA) in providing better analgesia and improving pulmonary function with MRFs.

Unilateral sensory, motor, and sympathetic block can be achieved when local anaesthetic is injected into the paravertebral space. As this space communicates with the intercostal space laterally and the epidural space medially, a 5-6 dermatome sensory block is possible with a single injection of 20 ml of local anaesthetic. Compared with epidural analgesia, PVB is relatively easy to perform, produces less sympathetic blockade, does not cause urinary retention or pruitis, and allows for an unimpeded neurological assessment. However, there is a small risk for pneumothorax, vascular puncture, pleural puncture and a possibility of toxicity due to the rapid absorption of Local Anaesthetic. TPB can be given by using surface landmarks, nerve stimulator guidance or Ultrasound Guidance (USG). A review suggested that USG blocks are more successful and safe than other techniques.