Wang P M, Fike C D, Kaplowitz M R, Brown L V, Ayappa I, Jahed M, Lai-Fook S J
Center for Biomedical Engineering, University of Kentucky, Lexington 40506.
J Appl Physiol (1985). 1992 Jun;72(6):2420-7. doi: 10.1152/jappl.1992.72.6.2420.
In a previous study, direct measurements of pulmonary capillary transit time by fluorescence video microscopy in anesthetized rabbits showed that chest inflation increased capillary transit time and decreased cardiac output. In isolated perfused rabbit lungs we measured the effect of lung volume, left atrial pressure (Pla), and blood flow on capillary transit time. At constant blood flow and constant transpulmonary pressure, a bolus of fluorescent dye was injected into the pulmonary artery and the passage of the dye through the subpleural microcirculation was recorded via the video microscope on videotape. During playback of the video signals, the light emitted from an arteriole and adjacent venule was measured using a video photoanalyzer. Capillary transit time was the difference between the mean time values of the arteriolar and venular dye dilution curves. We measured capillary transit time in three groups of lungs. In group 1, with airway pressure (Paw) at 5 cmH2O, transit time was measured at blood flow of approximately 80, approximately 40, and approximately 20 ml.min-1.kg-1. At each blood flow level, Pla was varied from 0 (Pla less than Paw, zone 2) to 11 cmH2O (Pla greater than Paw, zone 3). In group 2, at constant Paw of 15 cmH2O, Pla was varied from 0 (zone 2) to 22 cmH2O (zone 3) at the same three blood flow levels. In group 3, at each of the three blood flow levels, Paw was varied from 5 to 15 cmH2O while Pla was maintained at 0 cmH2O (zone 2).(ABSTRACT TRUNCATED AT 250 WORDS)
在之前的一项研究中，通过荧光视频显微镜对麻醉兔的肺毛细血管转运时间进行直接测量，结果显示胸部充气会增加毛细血管转运时间并降低心输出量。在离体灌注兔肺中，我们测量了肺容积、左心房压力（Pla）和血流对毛细血管转运时间的影响。在恒定血流和恒定跨肺压条件下，将一团荧光染料注入肺动脉，并通过视频显微镜在录像带上记录染料通过胸膜下微循环的过程。在回放视频信号时，使用视频光分析仪测量小动脉和相邻小静脉发出的光。毛细血管转运时间是小动脉和小静脉染料稀释曲线平均时间值的差值。我们在三组肺中测量了毛细血管转运时间。在第1组中，气道压力（Paw）为5 cmH2O，在血流分别约为80、约40和约20 ml·min-1·kg-1时测量转运时间。在每个血流水平，Pla从0（Pla小于Paw，区域2）变化到11 cmH2O（Pla大于Paw，区域3）。在第2组中，在恒定的Paw为15 cmH2O时，在相同的三个血流水平下，Pla从0（区域2）变化到22 cmH2O（区域3）。在第3组中，在三个血流水平的每一个水平上，Paw从5变化到15 cmH2O，而Pla保持在0 cmH2O（区域2）。（摘要截断于250字）
