The goal of this observational study is to learn about the long-term effects of the serratus anterior plane block (SAPB) in adult patients who suffered multiple unilateral anterolateral rib fractures within 24 hours of patient presentation to the emergency department. The main question it aims to answer is:

Does the SAPB for multiple anterolateral rib fractures demonstrate reduction in patient morbidity and mortality, including incidence of pneumonia, length of hospital stay, discharge disposition, and death, as compared to standard analgesic regimens.

The SAPB will be performed if a physician trained in the SAPB is available within 24 hours of injury. If a trained physician is not available and the patient meets inclusion criteria, they will receive parental analgesia with opioid therapy. They will be followed until date of hospital discharge, up until 60 days.

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

The study population will include a cohort of patients presenting within 24 hours of injury with two or more unilateral, anterior or lateral rib fractures requiring opioid analgesia that would be admitted to the trauma service at a single urban level 1 trauma center. The authors anticipate recruitment of 200 participants over the course of a study duration of 1 year.

The study protocol, Statistical Analysis Plan (SAP), and Informed Consent Form (ICF) will be shared.

Data requests can be submitted starting 10 months after article publication and the data will be made accessible for up to 12 months. Extensions will be considered on a case-by-case basis

Access to trial IPD can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA).