GAS PHASE DIFFUSION LIMITATION IN THE LUNG

虽然气体穿过肺部的扩散被普遍认为是有害的， 一个重要的运输过程，大多数肺气体交换模型 假设扩散的气相成分不影响 测量肺气体交换。 该项目将采用跟踪 静脉内或通过静脉内给药的各种惰性气体的量 吸入途径，以进一步研究我们的初步发现， 高分子量从肺中消除的效率较低， 与较低分子量的气体相比，我们发现 气相扩散限制。 因为数量上的差异 观察到的是小，数据将首先获得的温度和 Ostwald所需的血红蛋白氧饱和度校正 将使用的每种惰性示踪气体的分配系数。 一 静脉输注惰性气体的生理死腔的测量 气体将与相同气体被 通过吸入途径给药，以证实尚未证实的 假设气体交换对称。 这个实验将是 重复使用80%的氦气吸入气体混合物，以确定是否 与室内空气相比，用He-O2观察到的较大的（A-a）DO2也将 吸入的惰性微量气体 为了确认 我们观察到的惰性气体的分子量依赖性损伤 消除不代表气相扩散限制，我们将重复 这些研究使用三种痕量惰性气体，使用He-O2环境气体，以及 还重复通过吸入器施用痕量惰性气体的研究， 路线 最后是对温度、血红蛋白氧含量 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， 确定我们早期关于从大气中主动消除二氧化碳的报告 肺可以解释的基础上，我们以前未能解释， 这些新发现的因素。 拟议的研究将提供 关于这种气相扩散运输的量级的定量数据 在正常的气体交换过程中的机制，将提供一些数据， 目前的气体交换理论模型， 正在开发中，并将提供一种 提高所获得的用于多个惰性气体的数据的精确度， 气体消除技术

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.