Assessment of Morbidity and Mortality Following Serratus Anterior Plane Block (SAPB) for Unilateral Rib Fractures

Rib fractures are a common complication of blunt thoracic trauma, reported in 10% of all injured trauma patients. They are associated with significant long-term disability, decreased quality of life, and increased patient morbidity and mortality. Pain from multiple rib fractures can result in reduced respiratory effort, atelectasis, inability to clear secretions, and a reduction in vital capacity. This, in turn, can result in hypoxemia, pneumonia, and acute respiratory failure. Adequate and early pain management is therefore crucial to provide symptomatic relief, decrease splinting, and prevent secondary respiratory complications.

While systemic analgesia, notably opioids, are frequently used in the emergency department (ED) for pain control, they are associated with poor side effect profiles. Opioids place patients at risk for delirium, chronic addiction, respiratory depression, and constipation. Traditional regional anesthesia techniques, including paravertebral, intercostal and epidural injections, are resource-intensive, time consuming, limited in dermatomal distribution and associated with significant potential complications (diaphragmatic complications, local anesthetic toxicity, vasovagal syncope, pneumothoraces). Such techniques are not feasible in the ED. Ultrasound-guided fascial plane blocks have thus emerged as an alternative tool for proper pain control in patients with rib fractures in the ED. Fascial plane blocks include the serratus anterior plane block (SAPB) and the erector spinae plane block (ESPB).

The SAPB has demonstrated efficacy in providing safe analgesia for anterolateral rib fractures, while the ESPB has demonstrated efficacy in pain relief of posterior rib fractures. A benefit of SAPB is that it can be performed in the supine position, in contrast to other regional anesthesia techniques. The SAPB utilizes a linear transducer to identify the serratus anterior muscle and instill local anesthetic into the fascial plane overlying the muscle. The anesthetic targets the lateral cutaneous branches of the intercostal nerves, with a wide distribution centered around T3-T8. The anesthetic may also block the long thoracic and thoracodorsal nerve if injected superficial to the serratus anterior muscle. Recent studies have demonstrated improvement in chest wall pain scores and incentive spirometry (IS) following SAPB in adult patients with rib fractures. No SAPB attributed complications have been reported, likely related to the clear landmarks of the procedure and injection of anesthetic into a compartment distant from major vasculature. To date, no studies have investigated the effects of SAPB on morbidity and mortality as compared to standard oral or intravenous (IV) analgesics in patients with multiple rib fractures. The authors aim to prospectively assess whether SAPB for multiple anterolateral rib fractures demonstrates reduction in key outcome measures as compared to standard analgesic regimens. The study is a prospective cohort study which will take place at a single urban level 1 trauma center.

For patients who meet inclusion and exclusion criteria, SAPB will be utilized as part of a multimodal analgesia strategy if an emergency physician trained in the procedure is present in the ED within 24 hours of injury. If a SAPB-trained emergency physician is not available, the patient will be placed in the non-SAPB group. Patients will be enrolled in the study by clinicians participating in their care who are involved in performance of the SAPB. Morbidity and mortality, the composite outcome measures, will be assessed through various primary outcome measures, each indexed separately (see Outcome Measures section).

Inclusion criteria

• Patients over 18 years of age being treated in the Emergency Department at Jacobi Medical Center
• Presenting within 24 hours of injury
• Patient with 2 or more unilateral, anterior or lateral rib fractures
• Able to provide consent (patient or health care proxy)
• Clinical team believes the patient will require inpatient admission at the time of enrollment

Exclusion criteria

• Patients in traumatic arrest or hemodynamic instability
• Patient expected to be discharged from the hospital within 24 hours
• Prisoner
• Pregnancy
• Children less than 18 years of age
• The patient is known or is suspected to be allergic to anesthetic
• Significant pain from another traumatic and distracting injury
• Patients without the ability to consent (or no health care proxy to consent)
• Patients with bilateral or posterior rib fractures