Title :
Mechanisms of intrapulmonary gas mixing: models and experimental evidence
Author_Institution :
Dept. of Physiol., Max Planck Inst. for Exper. Med., Gottingen, West Germany
Abstract :
Incomplete mixing of inspired gas with lung-resident gas is reflected in the steady change of gas concentration of respiratory or inert gases late in expiration (sloping alveolar plateau). The mechanisms underlying mixing inefficiency have been studied experimentally in anesthetized, mechanically ventilated dogs, utilizing single-breath washout of insoluble and soluble inert gases (He/SF/sub 6/ and C/sub 2/H/sub 2//CHClF/sub 2/) applied by inspired air or mixed venous blood, each pair of test gases exhibiting equal solubility but differing diffusivity. On the basis of simplified lung models the following mechanisms contributing to incomplete intrapulmonary gas mixing were identified: unequal distribution of ventilation associated with sequential emptying of lung regions, diffusion-dependent series inhomogeneity (stratification), ventilation-perfusion inhomogeneity, and continuing gas exchange.<>
Keywords :
lung; physiological models; pneumodynamics; Freon 22; He-SF/sub 6/ mixture; acetylene; anaesthetised mechanically ventilated dogs; continuing gas exchange; diffusion-dependent series inhomogeneity; diffusivity; expiration; gas concentration; inert gases; inspired air; inspired gas incomplete mixing; intrapulmonary gas mixing; lung regions; lung-resident gas; mixed venous blood; mixing inefficiency; respiratory gases; sequential emptying; simplified lung models; single-breath washout; sloping alveolar plateau; solubility; stratification; ventilation; ventilation-perfusion inhomogeneity;
Conference_Titel :
Engineering in Medicine and Biology Society, 1988. Proceedings of the Annual International Conference of the IEEE
Conference_Location :
New Orleans, LA, USA
Print_ISBN :
0-7803-0785-2
DOI :
10.1109/IEMBS.1988.94729
