Simultaneous Washout of Helium and Sulfur Hexafluoride in Healthy Subjects and Patients with Chronic Bronchitis, Bronchial Asthma, and Emphysema1
- 1 October 1977
- journal article
- research article
- Published by American Thoracic Society in American Review of Respiratory Disease
- Vol. 116 (4) , 649-660
- https://doi.org/10.1164/arrd.1977.116.4.649
Abstract
Simultaneous multiple-breath washout curves of helium and sulfur hexafluoride were obtained for 39 healthy subjects, 29 patients with chronic bronchitis, 14 subjects with emphysema, and 12 patients with bronchial asthma. During the first breaths of the washout, the end-tidal concentration of helium was higher than that of sulfur hexafluoride. This end-tidal helium and sulfur hexafluoride partial pressure difference decreased toward zero (the “crossover point”) and became negative thereafter. In addition to the crossover point, the number of breaths and the cumulative expiratory volume for the washout down to 1 per cent of the inspired concentration were determined. In healthy subjects the crossover point appeared after 4 to 5 breaths; and washout down to 1 per cent of the inspired helium concentration was reached after 48 breaths. In subjects with chronic bronchitis the crossover point was reached after a mean of 8.3 breaths; 101 breaths were needed for the washout down to 1 per cent of the inspired heliu...Keywords
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