A 36-year-old man comes to the office due to chronic, mild dyspnea and fatigue. The patient also says that his mind seems "foggy" all the time and he is not able to think clearly. He has no significant past medical history and does not take any medication. He lives a sedentary lifestyle and has smoked a half-pack of cigarettes a day for 5 years. Blood pressure is 140/85 mm Hg, pulse is 84/min, and respirations are 18/min. BMI is 32 kg/m². Lung auscultation is unremarkable. Chest x-ray is normal. Arterial blood gas analysis shows partial pressure of oxygen (PaO₂) is 66 mm Hg and partial pressure of carbon dioxide (PaCO₂) is 58 mm Hg. His estimated alveolar to arterial oxygen gradient is 10 mm Hg. Which of the following best explains this patient's laboratory findings?

Question

Quizplus · Accepted Answer

Eductional Objective: Obesity hypoventilation syndrome commonly presents with chronic fatigue, dyspnea, and difficulty concentrating. Patients will have BMI >30 kg/m² and arterial blood gas while awake showing evidence of hypoventilation, including hypercapnia (PaCO₂ >45 mm Hg) and usually hypoxemia (PaO₂ <75 mm Hg). The expected alveolar to arterial oxygen gradient is normal (4-15 mm Hg) with hypoventilation.

A 36-Year-Old Man Comes to the Office Due to Chronic