title: The sloping alveolar plateau at synchronous ventilation.
abstract: We performed model calculations on the slope of the alveolar plateau at single breath washout of helium (He) and sulphurhexafluoride (SF6). Calculations wre carried out on an extensible axis-symmetric lung model, which was synchronously ventilated either equally or unequally. The calculated slopes of the alveolar plateau were small (<0.3%), which is in agreement with the results of other investigators. However, calculations carried out on a synchronously equally ventilated axis-asymmetric lung model related to the terminal lung unit (acinus), yielded slopes for the alveolar plateau ranging from 0 up to 14% per liter between 1.2 and 1.8 1 expired volume. Even with a post inspiratory apnea of 1 s, we still found slopes ranging from 0--4%. Our findings are in contrast to the conclusions of Engel et al. (1979), who ascribe the slope of the alveolar plateau to asynchronous unequal ventilation.
mesh_terms: D003201:Computers; D005652:Functional Residual Capacity; D006801:Humans; D008953:Models, Anatomic; D011650:Pulmonary Alveoli / Q000502:physiology*; D012123:Pulmonary Ventilation; D012126:Respiratory Dead Space; D014692:Ventilation-Perfusion Ratio