PULMONARY MICROCIRCULATORY HEMODYNAMICS

血液在肺毛细血管中停留的时间是主要的 肺部气体交换效果的决定因素。因此， 改变这种接触时间的生理机制可能会起到重要作用 监管职能。例如，在运动过程中，一些因素会减少 接触时间，以便每单位有更多的红细胞穿过毛细血管 时间，从而加强气体交换。然而，如果运输时间变成 速度太快，可能会导致动脉低氧血症。显而易见的重要性是 了解肺微循环血流动力学是如何调节的 引发了大量研究，但之前的调查人员被迫 使用间接技术，在红细胞毛细血管方面 传输时间，将肺视为单一的、同质的实体。在……里面 事实上，很可能是内部压力和流量的地区差异 肺脏在毛细血管转运方面存在区域差异。使用中 我们最近开发的活体视频荧光显微技术，我们 建议直接确定红血球所需的时间长度 细胞穿越肺毛细血管，并评估如何通过时间 作为生理变量的函数的变化(肺动脉和 静脉压、心输出量和肺毛细血管复张)。 特别强调研究减少运输时间的机制。 以增加气体交换。最后，我们将确定 荧光素标记中性粒细胞的滞留和通过时间 细胞是正常的和激活的。

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.