What occurs during a flail chest injury?

In the case of a flail chest injury, a segment of the chest wall becomes detached from the surrounding thoracic cage. This typically occurs when two or more adjacent ribs are broken in multiple places, resulting in a section of the rib cage that is no longer securely attached to the rest of the chest. This detachment leads to a paradoxical movement of that segment of the chest wall during respiration.

During inhalation, the injured portion moves inward due to negative pressure in the thoracic cavity, while the rest of the chest expands. Conversely, during exhalation, this segment will bulge outward. This paradoxical movement can severely impair ventilation and lead to respiratory distress, which requires immediate medical attention.

The critical aspect of identifying a flail chest is understanding that it involves the detachment of a segment of the rib cage, rather than merely a presence of fractures. Thus, recognizing this distinguishes it from other chest wall injuries that may not cause such significant mechanical dysfunction of breathing.