Review Question - QID 109932

A 57-year-old man presents to the emergency department with shortness of breath. The patient was found unconscious on a train by the conductor at the last train station on the line. He has a past medical history of diabetes, hypertension, IV drug abuse, and a 22 pack-year smoking history. The patient smells of vomit and is minimally responsive. His temperature is 99.5°F (37.5°C), blood pressure is 100/58 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 90% on room air. Palpation of the patient's upper abdomen causes him to recoil his limbs. There are scars over the patient's antecubital fossae. The patient suddenly becomes tachypneic with an O2 saturation of 75% on 4L of 100% oxygen. A chest radiograph is taken and shown in Figure A. Which disease process is the most likely cause of this patient's presentation?