Rebreathing and steady state pulmonary Do2, in the dog and in inhomogeneous lung models

Impaired lung diffusing capacity for nitric oxide and alveolar-capillary membrane conductance results in oxygen desaturation during exercise in patients with cystic fibrosis

“…However, it has been previously demonstrated that the heterogeneity of alveolar gas composition is diminished when measurements of diffusion capacity of the lungs are conducted using the rebreathe rather than the breathe hold method, because of the opportunity for better mixing. As such, the effects of functional inhomogeneities are reduced, although not completely suppressed because ventilation cannot be sufficiently increased [47]. Finally, in regards to the potential influence of hyperinflation on the assessment of DLCO, work by Baldi et al explored the influence of hyperinflation (using pulmonary function testing) and CT scanning for degree of emphesyma on DLCO.…”

Pulmonary Diffusing Capacity for Carbon Monoxide by Rebreathing in Awake Dogs

“…unequal distribution of VA, Dl and Q to Va-The effects of inhomogen eities on Dlo2 determined by rebreathing have been estimated for two-compartment lung models and shown to be considerable in spite of the homogenizing effect of re breathing [16], Corresponding calcula tions for rebreathing Dlco have not been performed, but the effects should be slightly less because the variance of 0 , if not excessive, is expected to have little ef fect. In any case, the effect of disregarding the presence of functional inhomogenei ties is underestimation of Dlco-(4) In theory, inequalities of VA/V A and Dl/V a should produce deviations of He and CO tracings from monoexponential time course.…”