A 60-year-old woman is admitted to hospital because of hypotension and respiratory distress. Vitals are: temperature 101 F, HR 110, RR 26, BP 80/50. A 3/6 systolic murmur is auscultated. Pulmonary artery catheterization shows cardiac output of 6.5 L/min (NR 4-5) and pulmonary capillary wedge pressure of 13 mm Hg (NR 5-16). Laboratory studies show:
Hemoglobin 13 g/dL
Leukocytes 19,000/μL
pH 7.27
PCO2 20 mm Hg
PO2 65 mm Hg
Which of the following is the most likely mechanism for this patient’s respiratory failure?
