GAS PHASE DIFFUSION LIMITATION IN THE LUNG

虽然气体在肺部的扩散被普遍认为是 一种基本的运输过程，大多数肺气体交换模型 假设扩散的气相成分不影响 肺气体交换的测量。该项目将采用TRACE 各种惰性气体的静脉注射或由 吸入途径以进一步调查我们的初步发现 高分子量在肺中的清除效率较低 与低分子气体的比较，发现我们已经将 到气相扩散限制。因为数量上的差异 观测到的数据很少，将首先获得关于温度和 Ostwald所需的血红蛋白氧饱和度校正 将使用的每种惰性痕量气体的分配系数。一个 静脉输注惰性气体生理死腔的测量 气体将与相同气体为 通过吸入途径给药以确认尚未证实的 气体交换对称性的假设。这项实验将是 重复使用80%氦吸入气体混合物来确定 与室内空气相比，用He-O2观察到的(A-a)DO2更大也将 由吸入的惰性痕量气体表现出来。试图确认 我们观察到的惰性气体分子量依赖性损伤 消除确实代表了气相扩散的限制，我们将重复 这些研究使用He-O2环境气体对三种痕量惰性气体进行研究，以及 也要重复研究通过吸入来管理微量惰性气体 路线。最后对温度、血红蛋白和氧气进行了修正 饱和度和气相扩散限制将应用于数据 用标准的多重惰性气体消除技术获得 确定我们之前关于主动消除二氧化碳的报告是否 肺脏可以根据我们以前未能解释的基础上解释 这些新发现的因素。拟议的研究将提供 气相扩散运移大小的定量数据 机制在正常的气体交换过程中，将提供多个数据 考虑两种对流的现有气体交换理论模型 和扩散，正在开发中，将提供一种手段 提高用于多重惰性的数据的精确度 气体排除技术。

While diffusion of gases across the lung is universally acknowledged to be an essential transport process, most models of pulmonary gas exchange assume that the gas phase component of diffusion does not influence measurements of pulmonary gas exchange. This project will employ trace amounts of various inert gases administered either intravenously or by the inhaled route to further investigate our preliminary findings that gases of high molecular weight are less efficiently eliminated from the lung in comparison with gases of lower molecular weight, finding we have attributed to gas phase diffusion limitation. Because the quantitative differences observed are small, data will first be obtained on the temperature and hemoglobin oxygen saturation corrections that are required for the Ostwald partition coefficients of each inert trace gas that will be used. A measurement of physiological dead space for an intravenously infused inert gas will be compared to an equivalent calculation made when the same gas is administered by the inhaled route to confirm the as yet undemonstrated assumption of the symmetry of exchange of gases. This experiment will be repeated utilizing an 80% Helium inhaled gas mixture to determine whether the larger (A-a) DO2 observed with He-O2 compared with room air will also be manifested by the inhaled inert trace gas. In an attempt to confirm that our observed molecular weight dependent impairment of inert gas elimination does represent gas phase diffusion limitation, we will repeat these studies with three trace inert gases using an He-O2 ambient gas, and also repeat the studies administering the trace inert gases by an inhaled route. Finally the corrections for temperature, hemoglobin oxygen saturation, and gas phase diffusion limitation will be applied to data obtained with the standard multiple inert gas elimination technique to determine whether our earlier report of active elimination of CO2 from the lung can be explained on the basis of our previous failure to account for these newly discovered factors. The proposed studies will provide quantitative data on the magnitude of this gas phase diffusive transport mechanism during normal gas exchange, will provide data for a number of current theoretical models of gas exchange incorporating both convection and diffusion that are under development and will provide a means of improving the precision of data obtained for use with the multiple inert gas elimination technique.