PULMONARY MICROCIRCULATORY HEMODYNAMICS

血液在肺毛细血管中停留的时间 肺的气体交换效率的决定因素。 因此，委员会认为， 改变这种接触时间的生理机制可能起重要作用 监管职能。 例如，在运动过程中， 接触时间，以便每单位有更多的红细胞穿过毛细血管 时间，从而增强气体交换。 然而，如果过境时间变得 过快则会导致动脉血氧不足。 明显的重要性 了解肺微循环血液动力学是如何调节的 促使了大量的研究，但以前的研究人员被迫 使用间接技术，在红细胞毛细血管方面， 通过时间，考虑肺作为一个单一的，均匀的实体。 在 事实上，很可能区域内压力和流量的差异 肺毛细血管通过的区域性差异。 使用in 活体视频荧光显微技术是我们最近开发的， 建议直接确定红血球所需的时间长度 细胞穿过肺毛细血管，并评估通过时间 作为生理变量（肺动脉和 静脉压、心输出量和肺毛细血管募集）。 特别强调研究减少过境时间的机制 以增加气体交换。 最后，我们将确定 荧光素标记的中性粒细胞的隔离和通过时间， 细胞正常并被激活。

The time that blood spends in the pulmonary capillaries is a major determinant of the gas exchange effectiveness of the lungs. Consequently, physiologic mechanisms which alter this contact time may serve important regulatory functions. For example, during exercise some factors reduce contact time so that more red blood cells traverse the capillaries per unit time, thereby enhancing gas exchange. If, however, transit times become too rapid, arterial hypoxemia can result. The obvious importance of understanding how pulmonary microcirculatory hemodynamics are regulated have prompted numerous studies, but previous investigators have been forced to use indirect techniques and, in terms of red blood cell capillary transit time, to consider the lung as a single, homogeneous entity. In fact, it is likely that regional differences in pressure and flow within the lung give rise to regional differences in capillary transit. Using in vivo video fluorescence microscopy techniques recently developed by us, we propose to determine directly the length of time required for red blood cells to traverse pulmonary capillaries and to evaluate how transit time changes as a function of physiologic variables (pulmonary arterial and venous pressures, cardiac output, and pulmonary capillary recruitment). Specific emphasis is placed on studying mechanisms that reduce transit time in order to increase gas exchange. Finally, we will determine the site of sequestration and transit time of fluorescein labeled neutrophils when the cells are normal and activated.