What defines a flail chest?

Flail chest is characterized specifically by the phenomenon where two or more ribs are broken in two or more places, creating a segment of the chest wall that moves independently from the rest of the thoracic cage during breathing. This abnormal segment, often referred to as a "flail segment," can lead to compromised ventilation and significant respiratory distress. When the chest rises, the flail segment may be drawn inward instead of outward, which disrupts normal respiratory mechanics.

A flail chest is a serious injury that typically occurs due to blunt trauma, and recognizing its presence is critical for effective management. The other options, while related to chest trauma, do not encapsulate the contradictory movement of the thoracic wall that characterizes a flail chest. An open chest wound, severe bruising, or a punctured lung can all occur with trauma, but they do not define the specific mechanics and implications of a flail chest injury.