A 54-year-old woman has progressive exertional dyspnoea. Spirometry shows a forced expiratory volume in one second of 2.4 L (reference greater than 2.0 L) and a normal FEV1/FVC ratio. Total lung capacity is normal, but diffusion capacity for carbon monoxide is 55% of predicted. Haemoglobin is 82 g/L (reference 120–160 g/L), and high-resolution computed tomography shows no interstitial lung disease. Which change most directly accounts for the reduced measured diffusion capacity?
Keep going with ten more like this one.
Practise moreMore from Biomedical Science
See allA 23-year-old man has recurrent episodes of muscle cramps during intense exercise. During an episode, plasma lactate rises from 1.2 to 1.5 mmol/L (reference 0.5…
Foundations · middle twist
A laboratory technician is found unconscious in a poorly ventilated garage. Arterial blood shows pH 7.39, PaO2 13.0 kPa (reference 10.7–13.3 kPa), and PaCO2 5.1…
Mechanisms of disease · common
A 68-year-old man develops sudden pleuritic chest pain and tachypnoea after prolonged immobility. Arterial blood gas analysis on room air shows pH 7.48, PaCO2 3…
Mechanisms of disease · common
A patient with profuse watery diarrhoea caused by enterotoxin receives an oral solution containing sodium and glucose. Before treatment, stool output is high an…
Foundations · common
A 7-month-old infant becomes lethargic after an overnight fast during gastroenteritis. Blood glucose is 1.9 mmol/L (reference 3.5–6.0 mmol/L), beta-hydroxybutyr…
Foundations · niche