Review Question - QID 214204

A 60-year-old man presents to the base camp clinic with dyspnea and shortness of breath. He is on an expedition to hike and see the world. After ascending to base camp, he became profoundly short of breath and began coughing. The patient has a past medical history of chronic obstructive pulmonary disease and heart failure with preserved ejection fraction. His temperature is 99.5°F (37.5°C), blood pressure is 177/98 mmHg, pulse is 120/min, respirations are 33/min, and oxygen saturation is 80% on room air. Physical exam is notable for bilateral crackles, wheezes, jugular venous distention, and bilateral pitting lower extremity edema. The patient becomes progressively more confused and is unable to stand or walk on his own. He is transferred by helicopter to the nearest hospital. The patient's chest radiograph upon arrival at the hospital (left) and 3 hours later (right) are seen in Figure A. Which of the following is the most likely diagnosis in this patient?