- Definition
- Flail chest is a condition where a segment of the chest wall becomes free-floating due to fractures of ≥3 consecutive ribs in ≥2 places
- This segment moves independently from the rest of the thoracic cage
- Normal chest wall mechanics
- During inspiration: chest wall expands, diaphragm contracts downward, generating negative intrathoracic pressure
- Negative pressure draws air into lungs
- Chest wall and ribs move outward in unison
- Pathophysiology
- Disruption of the structural integrity of the chest wall
- Flail segment becomes detached from normal rib continuity
- During inspiration:
- Negative intrathoracic pressure pulls the flail segment inward (paradoxical movement)
- This reduces tidal volume and impairs effective ventilation
- During expiration:
- Positive intrathoracic pressure pushes the flail segment outward
- Further contributes to inefficient ventilation
- Respiratory consequences
- Ineffective ventilation due to paradoxical motion
- V/Q mismatch from poor alveolar ventilation
- Hypoxia from both hypoventilation and underlying pulmonary contusion (common co-injury)
- Increased work of breathing → respiratory fatigue