Rupert Kelly, a 68-year-old man, presents with a 6-month history of worsening shortness of breath and headaches. His past history is essentially negative. He denies any history of asthma or cardiovascular disease. He does describe a 50-pack year history of smoking. He has a chronic cough that is worse in the morning and is non-productive of sputum. Although he generally does not exercise, he has noticed increased shortness of breath when climbing more than one flight of stairs. He reports fatigue and drowsiness despite 8 or more hours of sleep per night. His wife comments that he snores loudly and sometimes seems to stop breathing.