Analysis: For each SBW, the inspired and expired volumes, inspiratory and expiratory times, and the breath hold time were measured . RV was calculated by measuring the mass of helium inhaled and exhaled to determine the mass of helium remaining in the lung, as previously described . It was assumed that the mean helium concentration…
Study group: Twenty-one smokers and 21 nonsmokers were recruited from the community and hospital personnel. In both groups as previously reported , subjects denied recent respiratory symptoms. Spirometric testing revealed that the forced vital capacity (FVC), the forced expired volume in 1 s (FEV1) and the maximal mid-expiratory flows (FEF25-75) were within the 95% confidence…
The difference between the two types of manoeuvres was thought to be caused by differences in the relative contributions of several types of ventilation inhomogeneity. For SBWvc manoeuvres, a dominant mechanism of nonuniform gas distribution was convective dependent, topographical ventilation inhomogeneity due to asynchronous emptying of large regions with unequal specific ventilations . In contrast…
Smoking is associated with inflammation and fibrosis in small airways and alveoli , and vascular deficiency emphysema . Using conventional vital capacity single breath washout (SBWvc) manoeuvres without breath holding, abnormalities in the phase III slope of nitrogen were found in healthy smokers which correlated with pathological changes in the small airways .
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