Kim Sangho, Kong Robert L, Popel Aleksander S, Intaglietta Marcos, Johnson Paul C
Department of Bioengineering, University of California, San Diego, La Jolla, California 92093-0412, USA.
Microcirculation. 2006 Apr-May;13(3):199-207. doi: 10.1080/10739680600556878.
The cell-free layer between the erythrocyte column and the vessel wall is an important determinant of hydrodynamic resistance in microcirculatory vessels. The authors report a method for continuous measurement of the width of this layer.
The light intensity of a linear array of pixels perpendicular to the vessel axis is continuously determined from a video image of a microcirculatory vessel. A threshold level based on Otsu's method is used to establish the interface between the cell-free layer and the erythrocyte column. To test the method, video images at 750-4500 frames/s were obtained from venules and arterioles in rat spinotrapezius muscle at normal and reduced arterial pressures before and after induction of erythrocyte aggregation with Dextran 500. The current measurements were compared to manual measurements of the same images.
Values obtained by the manual and the new methods were in agreement within the 95% confidence limit by the Bland-Altman analysis and within 90-95% range by the correlation coefficient (R2). The more frequent measurements reveal substantial, rapid variations in cell-free layer width and changes in mean values with alteration of arterial pressure and red cell aggregability.
A new, computer-based technique has been developed that provides measurements of rapid, time-dependent variations in the width of the cell-free layer in the microcirculation.
红细胞柱与血管壁之间的无细胞层是微循环血管中流体动力阻力的重要决定因素。作者报告了一种连续测量该层宽度的方法。
从微循环血管的视频图像中连续确定垂直于血管轴的像素线性阵列的光强度。基于大津法的阈值水平用于确定无细胞层与红细胞柱之间的界面。为了测试该方法，在使用右旋糖酐500诱导红细胞聚集之前和之后，在正常和降低的动脉压下，以750 - 4500帧/秒的速度从大鼠斜方肌的小静脉和小动脉获取视频图像。将当前测量结果与相同图像的手动测量结果进行比较。
通过布兰德 - 奥特曼分析，手动测量和新方法获得的值在95%置信限内一致，通过相关系数（R2）在90 - 95%范围内一致。更频繁的测量揭示了无细胞层宽度的大量、快速变化以及随着动脉压和红细胞聚集性改变而出现的平均值变化。
已开发出一种新的基于计算机的技术，可测量微循环中无细胞层宽度的快速、随时间变化的情况。
