A 43-year-old woman presents with acute-onset pleuritic chest pain and dyspnea 4 days after pelvic surgery. Vital signs reveal HR 118 bpm, RR 28/min, BP 132/84 mmHg, SpO2 88% on room air. Arterial blood gas demonstrates pH 7.48, PaCO2 32 mmHg, PaO2 68 mmHg. CT pulmonary angiography shows wedge-shaped opacity. She denies calf pain. Which physiologic mechanism best explains the ventilation-perfusion mismatch in the affected lung units?
- A)Loss of surfactant causing alveolar collapse
- B)Global hypoventilation with normal A a gradient
- C)Perfusion without ventilation causing shunt
- D)Decreased diffusion from fibrotic thickening only
- E)Ventilation without perfusion causing increased dead spaceGABARITO
Explicação
Pulmonary embolism blocks perfusion to ventilated alveoli, creating dead space physiology with a very high V Q ratio. Reflex hyperventilation commonly produces respiratory alkalosis, and hypoxemia results from overall V Q mismatch. Recent surgery is a classic ... Ver explicação completa e trilha adaptativa →