A 51-year-old man is evaluated for a 3-month history of worsening lower extremity edema. He has a 15-pack-year smoking history but reports no cough or sputum production.
BMI is 42. Breath sounds are diminished without wheezing. There is bilateral edema of the legs. Arterial pH is 7.36, PO2 is 52 mm Hg (6.9 kPa), and PCO2 is 53 mm Hg (7.0 kPa). Chest radiograph shows only reduced lung volumes.
Which of the following is the most likely diagnosis?
