Acute Respiratory Failure And Hypoxemia Practice Test

A 65-year-old man with chronic systolic heart failure presents with sudden severe dyspnea, orthopnea, and cough productive of pink frothy sputum after missing diuretics. Vitals: HR 122/min, BP 190/110 mm Hg, RR 34/min, SpO2 80% on room air. Exam shows diffuse crackles, S3, and elevated JVP. ABG on nonrebreather: pH 7.49, PaCO2 30 mm Hg, PaO2 58 mm Hg. Chest X-ray shows bilateral alveolar infiltrates and cardiomegaly. Potential causes of acute hypoxemia include pulmonary edema, pneumonia, pulmonary embolism, and COPD exacerbation. What is the most likely cause of hypoxemia in this patient?

A 65-year-old man with HFrEF (EF 25%) and long-standing hypertension presents with 2 hours of severe dyspnea and anxiety. He reports orthopnea, waking up gasping, and coughing up pink frothy sputum. Medications include furosemide (missed for 3 days), lisinopril, and carvedilol. Vitals: T 36.8°C, HR 118/min, BP 178/102 mm Hg, RR 32/min, SpO2 82% on room air. He sits upright and uses accessory muscles. Exam shows cool extremities, diffuse crackles to apices, and an S3 gallop; no wheezing. JVP is elevated and there is 2+ pitting edema. Initial labs: BNP 1450 pg/mL, troponin negative, WBC 9,000/µL. ABG on 6 L/min nasal cannula: pH 7.47, PaCO2 31 mm Hg, PaO2 55 mm Hg. Chest X-ray shows bilateral perihilar “bat-wing” opacities, cardiomegaly, and small bilateral pleural effusions. ECG shows sinus tachycardia. Potential causes of acute hypoxemia considered include pneumonia, pulmonary embolism, COPD exacerbation, and cardiogenic pulmonary edema. Which of the following is the most appropriate initial management?