A 22-year-old previously healthy man presents with acute dyspnea and wheezing. Vital signs: BP 118/76 mmHg, HR 112/min, RR 28/min, temperature 37.2°C, SpO2 92% on room air. Chest X-ray shows hyperinflation without infiltrates. Spirometry reveals FEV1 of 58% predicted. He denies fever and recent infection. He uses albuterol inhaler occasionally but takes no daily controller medications. Which of the following best describes the ventilation-perfusion ratio at the lung apex compared with the base during acute bronchospasm?
- A)Approximately equal at apex and base because both are zero at end expiration
- B)Zero at the apex because alveoli are maximally expanded
- C)Lower at the apex because perfusion exceeds ventilation there
- D)Higher at the apex because perfusion decreases more than ventilationGABARITO
- E)Infinite at the base because perfusion is greatest there
Explicação
Both ventilation and perfusion are greater at the lung bases, but perfusion falls more dramatically than ventilation toward the apex. Therefore the V Q ratio is highest at the apex. This produces relatively higher alveolar oxygen and lower alveolar carbon diox... Ver explicação completa e trilha adaptativa →