uk-dipimc MCQ (SBA): Flail Chest

A 52-year-old male is trapped in a vehicle following a head-on collision at approximately 60 mph. Fire and rescue are performing extrication. The patient is conscious but complaining of severe chest pain and difficulty breathing. On examination, there is paradoxical movement of the right chest wall. SpO2 is 88% on air, respiratory rate is 32, and heart rate is 118 bpm. What is the most likely diagnosis?