A 67-year-old man with severe lobar pneumonia presents with profound hypoxemia (SpO2 78% on room air). Vital signs show BP 142/88, HR 118, RR 28, Temp 39.2°C. Chest X-ray demonstrates left lower lobe consolidation with air bronchograms. Bronchoscopy reveals complete obstruction of a segmental bronchus by purulent material while perfusion to that region remains intact. He denies recent chest pain. Which of the following best describes the ventilation-perfusion physiology in the affected region?
- A)Pure hypoventilation with a normal A a gradient across the whole lung
- B)Reduced diffusion only with preserved ventilation and perfusion
- C)V Q ratio of 1 representing normal gas exchange
- D)V Q ratio of infinity representing dead space
- E)V Q ratio of 0 representing shunt physiologyGABARITO
Explicação
Perfusion without ventilation creates a shunt, which has a V Q ratio of 0. In lobar pneumonia or airway obstruction, blood passes through nonventilated alveoli and remains poorly oxygenated, causing hypoxemia that is often less responsive to supplemental oxyge... Ver explicação completa e trilha adaptativa →