A 49-year-old man has had increasing dyspnea for the 4 years. He has an occasional cough with minimal spu- production On physical examination, his lungs are hy- perresonant with expiratory wheezes. Pulmonary function tests show increased total lung capacity(TLC) with slightly increased FVC and decreased FEV, and FEV,/FVC ratio Arte- rial blood gas measurement shows pH of 7.35: Po2, 65 mm Hg; and Pco,, 50 mm Hg. Which of the following disease processes should most often be suspected as a cause of these findings?