Traumatic rib fractures are very common with some estimates indicating a prevalence in more than one-third of blunt trauma patients and more than two-thirds of thoracic trauma patients. Poorly treated pain and overtreatment with opiates in these patients leads to splinting, rapid shallow breathing, ineffective cough, inability to clear secretions, poor mobility and high incidence of subsequent pneumonia. Startlingly, the incidence of pneumonia in the elderly is greater than 50% in those with six or more fractured ribs and their estimated mortality is 33%. It is estimated that each fractured rib in the elderly is associated with an additional 5% risk of mortality(1).
Because of the severity of the morbidity and mortality associated with rib fractures, it is imperative to offer effective treatment options to these patients. Many academic centers have even developed rib fracture protocols in an effort to standardize and optimize management. In addition to oral and parenteral opioids for pain management, thoracic epidurals and paravertebral catheters have been the gold standard regional technique. However, in recent years thoracic wall fascial plane blocks have been developed and are gaining traction in the treatment of rib fractures. Though the research thus far is somewhat limited, the erector spinae block and the serratus anterior block have been shown to be effective opioid-sparing regional techniques, especially when combined with an aggressive multimodal regimen. The aim of this discussion, thus, is to clarify when and how to best employ these techniques.
Multimodal analgesia usually provides sufficient pain relief in younger patients and those with three rib fractures or less. However, a regional anesthesia technique should be considered in patients that are 65 years and older, patients that have pain scores greater than 6 out of 10 at rest, patients with four or more rib fractures, and those with worsening symptoms after 48 hours of conservative management(2). Thoracic epidurals have traditionally been the most commonly used technique. Anesthesiologists are highly skilled at performing them, they do not require ultrasound guidance and they are effective at reducing pain scores and improving respiratory parameters. The local anesthetic solution infused though a thoracic epidural catheter blocks spinal nerves as they emerge from the spinal cord bilaterally so one catheter is useful for a patient with both left and right-sided fractures. An epidural, however, is not without risks as it can cause significant hypotension and is contraindicated in several scenarios that can be associated with a trauma patient such as elevations in intracranial pressure, coagulopathy, and spinal cord injury. Also, proper positioning for an epidural can be challenging and extremely painful for the patient.
Thoracic paravertebral blocks anesthetize the ventral and dorsal rami of ventral nerves in the paravertebral space and can achieve multilevel blockade with a single large volume injection or by infusion through a catheter. These blocks lower pain scores, decrease opioid requirements, and improve respiratory parameters, similar to a thoracic epidural. This technique is commonly used because it is relatively easy to perform and it does not require ultrasound-guidance. It also does not cause the sympathectomy and subsequent hypotension that is associated with a thoracic epidural and it is not as strictly limited in patients with coagulopathy. Disadvantages of paravertebral blocks are the risk of pneumothorax and vascular puncture. They are not ideally suited for patients with bilateral rib fractures and, similar to a thoracic epidural, proper patient positioning can be difficult.
Thoracic wall fascial plane blocks are simple to perform and are growing in popularity as an alternative regional technique for the treatment of rib fractures. The two most commonly performed for the treatment of rib fractures are the erector spinae block and the serratus anterior block. In an erector spinae block, local anesthetic is placed between the erector spinae muscle and the transverse process either with or without ultrasound guidance. Additionally, a catheter may be used for a continuous infusion. The theory behind the efficacy of this block is that the costotransverse ligament is permeable due to fenestrations, allowing the local anesthetic to reach the paravertebral space. Since the block needle does not need to be advanced past the transverse process, this block has less potential for complications when compared to a paravertebral block. The negligible risk for hypotension, motor block, vascular injury and inadvertent neuraxial spread make this block a very appealing option. This block is also not contraindicated in patients with an altered coagulation status. It can be easily performed with the patient in the lateral position. If placing a catheter is not an option, liposomal bupivacaine can be considered, although there is no data in the literature to support its efficacy in erector spinae blocks for treatment of pain due to rib fractures.
Serratus anterior blocks are an additional option to treat rib fracture pain and have been shown to reduce opioid use and improve pain scores in patients after thoracotomy and those suffering with rib fractures, though data is limited. This technique blocks lateral cutaneous branches of interscostal nerves in a continuous dermatomal fashion, either with high volume single injection of local anesthetic or with a continuous infusion catheter placed into the plane above or below the serratus anterior in the midaxillary line anywhere between the second and seventh ribs. This block only provides analgesia to the anterior two-thirds of the chest so it must be reserved for isolated anterior rib fractures. Similar to the erector spinae block, coagulopathies, neurologic damage, and other coexisting traumatic injuries do not preclude its use. A discreet advantage that sets this block apart from the others is that it can be performed while the patient is in the supine position avoiding uncomfortable repositioning of the patient. Again, liposomal bupivacaine can be used for this block since it is a fascial plane block, but data is limited.
In summary, traumatic rib fractures can be associated with tremendous morbidity and mortality, worsened by age, increasing number of rib fractures, and concurrent traumatic injuries. Effective analgesia with the use of regional techniques should be considered early. More comprehensive data is needed to study the effects of these fascial plane blocks on opioid use, hospital length of stay, and pulmonary complications. Given the drawbacks and potential contraindications of epidural and thoracic paravertebral blocks, the safety profile of the erector spinae and serratus anterior blocks are excellent alternatives for pain control in patients with multiple rib fractures.
