A 50-year-old man Shahid K. John has had increasing dyspnea for the past 3 years with associated occasional cough but little sputum production. Auscultation reveals that his lungs are hyper-resonant and is associated with expiratory wheeze. Pulmonary function tests reveal increased total lung capacity (TLC) and slightly increased FVC. There is decreased FEV1 and FEV1/FVC ratio also. ABG analysis reveals pH of 7.35, pO2 of 60 mm Hg and pCO2 of 48 mm Hg. What is the most likely diagnosis?