Key points

• Flail chest is a severe thoracic injury that can cause significant respiratory compromise, primarily due to associated pulmonary contusion rather than mechanical instability alone.
• The hallmark sign is paradoxical chest wall movement, but this may not always be visible.
• Flail chest is unlikely to be the only injury; a high index of suspicion for associated injuries (pneumothorax, hemothorax, intra-abdominal trauma) is essential.
• Management focuses on pain control, optimizing oxygenation, and careful monitoring & treatment of associated injuries.

Overview

Flail chest is defined as ≥3 consecutive ribs each fractured in ≥2 places, creating a free-floating chest wall segment that moves paradoxically during respiration.

It is frequently accompanied by pulmonary contusion, which is the primary driver of respiratory compromise rather than the mechanical instability alone.

Recognition and assessment

The classic sign is paradoxical chest wall movement - the flail segment moves inward on inspiration and outward on expiration. Paradoxical motion may not be visible due to patient positioning, muscle splinting, or patient habitus (obesity, large muscle mass, breast tissue).

Assessment priorities include:

• Chest wall palpation for tenderness, crepitus, and deformity
• Auscultation for decreased air entry (concurrent pneumothorax/hemothorax is common)
• SpO₂ monitoring and end-tidal CO₂ where available
• High index of suspicion for associated injuries: pulmonary contusion, pneumothorax, hemothorax, intra-abdominal trauma

Interventions

Analgesia

Multimodal analgesia should be initiated as early as possible.

• Patients may attempt to splint their chest wall with shallow breathing due to pain, which can exacerbate hypoventilation and lead to atelectasis and pneumonia.
• Attempt to provide effective pain control while minimizing respiratory depression.

Oxygenation and ventilation

• Supplemental high-flow oxygen should be provided, as is standard for all patients with significant trauma.
• For spontaneously breathing, alert, and cooperative patients with marginal respiratory status, noninvasive positive-pressure ventilation (CPAP) can serve as internal pneumatic splinting and has been shown to reduce rates of intubation, atelectasis, and pneumonia compared to obligatory mechanical ventilation.

Positioning

If spinal precautions allow, position the patient with the head of the bed 90 degrees; sitting upright can reduce work of breathing. If lateral positioning is necessary, position the injured side up.

References

1. Surgical Stabilization of Rib Fractures (SSRF): The WSES and CWIS Position Paper
   Sermonesi G, Bertelli R, Pieracci FM, et al.
   World Journal of Emergency Surgery : WJES. 2024;19(1):33. doi:10.1186/s13017-024-00559-2
2. Management of Pulmonary Contusion and Flail Chest: An Eastern Association for the Surgery of Trauma Practice Management Guideline
   Simon B, Ebert J, Bokhari F, et al.
   The Journal of Trauma and Acute Care Surgery. 2012;73(5 Suppl 4):S351-61. doi:10.1097/TA.0b013e31827019fd
3. The 2023 WSES Guidelines on the Management of Trauma in Elderly and Frail Patients
   De Simone B, Chouillard E, Podda M, et al.
   World Journal of Emergency Surgery : WJES. 2024;19(1):18. doi:10.1186/s13017-024-00537-8
4. Blunt Thoracic Trauma: Recent Advances and Outstanding Questions
   Parry NG, Moffat B, Vogt K.
   Current Opinion in Critical Care. 2015;21(6):544-8. doi:10.1097/MCC.0000000000000251
5. Prehospital Trauma Compendium: Traumatic Pneumothorax Care: Position Statement and Resource Document of NAEMSP
   Lyng JW, Ward C, Angelidis M, et al.
   Prehospital Emergency Care. 2024;1-21. doi:10.1080/10903127.2024.2416978
6. Thoracic Trauma WSES-AAST Guidelines
   Coccolini F, Cremonini C, Moore EE, et al.
   World Journal of Emergency Surgery : WJES. 2025;20(1):78. doi:10.1186/s13017-025-00651-1
7. Prehospital Decompression of Pneumothorax: A Systematic Review of Recent Evidence
   Robitaille-Fortin M, Norman S, Archer T, Mercier E.
   Prehospital and Disaster Medicine. 2021;36(4):450-459. doi:10.1017/S1049023X21000509
8. 2024 American Heart Association and American Red Cross Guidelines for First Aid
   Hewett Brumberg EK, Douma MJ, Alibertis K, et al.
   Circulation. 2024;150(24):e519-e579. doi:10.1161/CIR.0000000000001281
9. Early Surgical Stabilization of Multiple Rib Fractures and Flail Chest Is Associated With Better Outcomes Compared With Nonoperative Management
   Kwon J, Zakhary B, Coimbra BC, Sarani B, Coimbra R.
   The Journal of Trauma and Acute Care Surgery. 2025;01586154-990000000-01119. doi:10.1097/TA.0000000000004770
10. The pre-hospital management of life-threatening chest injuries: a consensus statement
    Caroline Leech, Keith Porter, Richard Steyn, Colville Laird, Imogen Virgo, Richard Bowman, & David Cooper
    The Royal College of Surgeons of Edinburgh [archived 2024-05-25]
11. Flail Chest Management
    Regional Paramedic Program for Eastern Ontario. 2024 [archived 2026-02-19]