Q. A 69-year-old man presented to the outpatient department in respiratory distress and claims “I just can’t stop coughing especially in the mornings.” The patient states he gradually started coughing a few years ago. Recently, he noticed sputum over the last month. The patient has smoked 20 cigarettes per day since law school, which he became a habit and a way to reduce stress. His vitals are normal with the exception of a raised respiratory rate of 22/min. On examination, there are coarse inspiratory crackles and hype- resonant lung fields. Chest x-ray shows a flattened diaphragm with increased bronchovesicular markings. What is the most likely diagnosis?