A 45-year-old man comes to the physician in January for a health maintenance examination. He reports a 4-month history of fatigue and mild depression. Vitals are normal. Laboratory studies show:
Hemoglobin 15 g/dL
pH 7.38
pCO2 46 mmHg
HCO3– 29 mEq/L
Which of the following is the most likely diagnosis?
Carbon monoxide poisoning
Cardiac shunt
Cor pulmonale
Obstructive sleep apnea
Salicylate poisoning
