Definition of Flail Chest
Flail chest is a clinical finding characterized by paradoxical movement of a chest wall segment during respiration, resulting from a contiguous segment of 3 or more consecutive ribs fractured at 2 or more places. 1
Key Distinction: Clinical vs. Radiographic Finding
- Flail chest is the clinical finding of paradoxical chest wall movement with respirations 1
- Flail segment is the radiographic finding of the anatomic injury pattern (≥3 consecutive ribs fractured at ≥2 sites) 1
- This distinction is critical and not universally recognized among clinicians, leading to confusion in patient management 1
Clinical Presentation
- Patients typically present with rapid breathing, respiratory distress, and visible paradoxical chest wall movement 2
- The affected chest wall segment moves inward during inspiration and outward during expiration (opposite of normal chest wall mechanics) 2
- Patients may develop shock, particularly when combined with underlying pulmonary contusion 2
Epidemiology and Significance
- Flail chest occurs in approximately 2-4% of blunt chest trauma cases 3
- Field diagnosis is rare, with only 0.002% of trauma patients and 0.02% of chest injury patients having documented flail chest 1
- Mortality ranges from 10-15% 3
- Trauma patients with flail chest have significantly increased risk of respiratory failure and mortality compared to those with simple rib fractures 1
Important Clinical Caveat
The terminology "chest wall instability or deformity" is often used in field triage settings because the specific diagnosis of "flail chest" is rarely made by EMS providers in the field environment 1. The broader terminology ensures identification of severe chest wall injuries requiring transport to the highest level trauma center 1.