Uneven ventilation in advanced silicosis. A study using the single-breath oxygen test

Intrapulmonary gas distribution was studied in 18 patients with conglomerate silicosis using the standardized single-breath O2 test. To avoid the influence of chronic bronchitis and emphysema only patients without obstructive ventilatory impairment were tested. An increased N 2 gradient was found in 10 patients; the mean value in patients was highly significantly greater than that of normal subjects of similar age and smoking habits. The pathogenesis and physiological consequences of this ventilation unevenness are discussed.