Review Question - QID 213765

A 33-year-old man presents to the emergency department after a motor vehicle collision. He was the unrestrained driver in a high-speed collision into a telephone pole. The patient was thought to be intoxicated with multiple substances. His temperature is 99.0°F (37.2°C), blood pressure is 119/70 mmHg, pulse is 133/min, and respirations are 15/min. His oxygen saturation is 95% on room air. The patient's primary and secondary surveys are completed and are notable only for multiple abrasions over his chest and abdomen. The patient is intubated for his Glasgow Coma Scale of 7. A CT scan of the patient's head, neck, and torso is remarkable only for multiple bilateral rib fractures. The patient is admitted to the ICU. The following day, it is noted that his oxygen saturation is persistently dropping despite an increasing FiO2. A chest radiograph is performed as seen in Figure A. The patient is currently on a positive end-expiratory pressure (PEEP) of 7 mmHg and has a PaO2 of 80 mmHg and a FiO2 of 40%. Which of the following is the most likely etiology of this patient's symptoms?