Acute Respiratory Failure And Hypoxemia Practice Test

A 70-year-old woman with obesity hypoventilation syndrome presents with lethargy and dyspnea. Vitals: RR 8/min, SpO2 85% on room air. ABG: pH 7.30, PaCO2 60 mm Hg, PaO2 56 mm Hg, HCO3− 25 mEq/L. Chest X-ray shows low lung volumes. Potential causes of hypoxemia include hypoventilation, PE, pneumonia, and heart failure. What is the most likely diagnosis based on the clinical presentation?

A 70-year-old woman with obesity hypoventilation syndrome (BMI 44 kg/m²) and untreated obstructive sleep apnea presents with 2 days of worsening lethargy and dyspnea. Family reports she has been “hard to wake up” and snores loudly. She denies chest pain and fever. Vitals: T 36.9°C, HR 96/min, BP 132/78 mm Hg, RR 10/min, SpO2 86% on room air. She appears drowsy with shallow breathing. Exam shows no wheezes or crackles; mild bilateral ankle edema. Initial labs: BMP normal, HCO3− 24 mEq/L. ABG on room air: pH 7.29, PaCO2 62 mm Hg, PaO2 58 mm Hg. Chest X-ray shows low lung volumes without infiltrate. Potential causes of acute hypoxemia include hypoventilation, pulmonary embolism, pneumonia, and heart failure. Which of the following is the best initial treatment?