Carlie Wilson, MS4
Article: Luftig, et al. “Successful emergency pain control for posterior rib fractures with ultrasound-guided erector spinae plane block.” American Journal of Emergency Medicine 2018; 36: 1391-96.
The idea: Recommendations for pain management of rib fractures include a combination of regional anesthesia (RA) and pharmacotherapy. Traditional RA techniques such as epidurals, paravertebral and intercostal blocks are technically complex with significant potential complications and are generally not used in the ED. US guided thoracic plane blocks are superficial, safer and easier to perform making them more suitable for ED patients. In 2010, the serratus anterior plane block technique was introduced. While this block effectively treats pain associated with lateral and anterior chest wall trauma, there is unreliable coverage for posterior rib fractures. The erector spinae plane block (ESPB) targets the posterior thorax making it a more suitable treatment for posterior traumatic injury. This paper presents the first description of ESPB utilized for pain control in the ED.
Background: Ribs are innervated by thoracic spinal nerves, which branch into ventral and dorsal rami. Ventral rami become intercostal nerves that innervate the lateral and anterior chest wall while dorsal rami innervate the posterior chest wall. The ESPB targets the erector spinae plane, which lies between the transverse processes of the spine and the overlying erector spinae muscles. Local anesthetic injected into this plane spreads anteriorly to anesthetize the ventral ramus as well as cephalocaudal extending 3 vertebral levels above and 4 levels below the injection point. This results in extensive thoracic anesthesia to the posterior and a large portion of the anterior and lateral chest wall.
Cases: Three cases are cited in this article (ranging in age from 38 to 79), all with posterior rib fracture(s) who had severe chest wall pain prior to ESPB. Within 30 mins of performing the block, all patients had effective analgesia, able to breath and move with minimal pain.
Technique:
1. Position patient in prone or lateral decubitus position with patient lying on unaffected side.
2. For rib fractures, target the transverse process that coincides with the area the patient finds most painful. However substantial spread of local anesthetic allows for flexibility in block placement location.
3. Perform a survey scan to identify key bony structures. Using the linear transducer in the sagittal plane, place the probe over the midline to identify the vertebral spinous process (superficial hyperechoic structure in midline creating shadow). Slide probe 3cm laterally toward side to be blocked and identify the transverse process (next most superficial bony structure, more blunted, thicker and wider than rib with underlying pleura difficult to discern). Slide the probe beyond the target laterally over the costotransverse junction to differentiate between the transverse process and rib. The transverse process should abruptly disappear and the posterior rib will come into view (deeper, rounder, thinner with highly visible pleura).
4. Stabilize probe over the transverse process and identify a needle insertion site 1-2cm above or below the probe. After sterile prep, place a local anesthetic skin wheal at the insertion site, insert the block needle at a 30-45 degree angle until the needle tip is visible. Continue advancing the needle with in-plane US guidance to the posterior surface of the targeted transverse process (firm end point upon contacting bone).
5. Gradually inject a total of 20-40mL of local anesthetic, observing the anechoic fluid spread to separate the erector spinae muscle from the transverse process in the erector spinae plane. Trunk anesthesia usually develops within 30 min.
Risks and Limitations: The major risk is local anesthetic systemic toxicity, which can be avoided by using dilute anesthetic (e.g. 40mL of 25% bupivacaine). Theoretically the needle could cause a pneumothorax or puncture the epidural space (however this would require significant operator error as the target transverse processes act as a shield to deeper structures). Limitations include positioning (especially in severely injured patients) and body habitus (poor candidate if >5cm of tissue from skin to transverse process).
The takeaway: Posterior rib fractures are common and can be exceedingly painful with limited options for pain management in the ED. Early, aggressive pain management with regional anesthesia is a crucial element of rib fracture management to optimize pulmonary function and reduce opioid-related complications. Although it seems that more research is needed, this article suggests that ESPB offers a highly favorable efficacy, feasibility and safety profile requiring only a single extrathoracic injection to provide significant trunk analgesia. The authors advocate that this technique should be incorporated into ER care of patients with posterior rib fractures.