A 45-year-old man sustains blunt chest trauma with three or more adjacent ribs fractured in two places each, producing a free-floating segment that moves paradoxically with respiration. The single most important cause of his hypoxaemia is:

• A Paradoxical airflow between the injured and uninjured lung
• B Underlying pulmonary contusion of the lung beneath the flail segment ✓
• C Mechanical splinting leading to hypoventilation from pain alone
• D Displacement of fractured rib ends lacerating the pleura

Explanation

Modern studies show the flail segment itself contributes little to hypoxaemia; the dominant lesion is pulmonary contusion of the underlying lung, which causes alveolar haemorrhage, oedema and shunting. Treatment is therefore directed at aggressive analgesia, chest physiotherapy and ventilatory support when contusion progresses rather than at mechanical stabilisation of ribs. Pain splinting worsens things but is secondary, and paradoxical airflow is an old concept largely disproved. Recognising contusion also warns of delayed deterioration over 24 to 48 hours.

Reference: Sabiston Textbook of Surgery, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.