A 48-year-old woman with severe obesity and a 40 pack-year smoking history presents with morning headaches and daytime somnolence. Vital signs show BP 148/92 mmHg, HR 102 bpm, RR 18/min, SpO2 88% on room air. She reports progressive dyspnea and denies orthopnea. Arterial blood gas while awake reveals pH 7.33, PaCO2 58 mmHg, and PaO2 66 mmHg. Chest X-ray shows hyperinflation without focal infiltrates. Which of the following best explains this patient's gas exchange abnormality?
- A)Right to left shunt from pulmonary arteriovenous malformations
- B)Loss of elastic recoil causing dynamic airway collapse
- C)Selective diffusion limitation due to thickened alveolar walls
- D)Chronic alveolar hypoventilation causing hypercapniaGABARITO
- E)Acute increase in physiologic dead space from thromboembolism
Explicação
Chronic alveolar hypoventilation causing hypercapnia is correct. Obesity hypoventilation syndrome produces daytime hypercapnia and hypoxemia because excessive body mass impairs chest wall mechanics and ventilatory drive. Morning headaches and somnolence are co... Ver explicação completa e trilha adaptativa →