Air inside of blood vessels is a phenomenon known as gas embolism. During the past years, studies have been performed to assess the influence of air bubbles in microcirculation. In this study, we investigated the flow of bubbles in a microchannel network with several bifurcations, mimicking part of a capillary system. Thus, two working fluids were used, composed by sheep red blood cells (RBCs) suspended in a Dextran 40 solution with different hematocrits (5% and 10%). The experiments were carried out in a polydimethylsiloxane (PDMS) microchannel network fabricated by a soft lithography. A high-speed video microscopy system was used to obtain the results for a blood flow rate of 10 µL/min. This system enables the visualization of bubble formation and flow along the network. The results showed that the passage of air bubbles strongly influences the cell's local concentration, since a higher concentration of cells was observed upstream of the bubble, whereas a lower local hematocrit was visualized at the region downstream of the bubble. In bifurcations, bubbles may split asymmetrically, leading to an uneven distribution of RBCs between the outflow branches.

中文翻译：

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微通道网络中血液流动中的气泡：对局部血细胞比容的影响。

血管内的空气是一种称为气体栓塞的现象。在过去的几年中，已经进行了研究以评估气泡在微循环中的影响。在这项研究中，我们研究了具有几个分叉的微通道网络中气泡的流动，模拟了毛细管系统的一部分。因此，使用了两种工作液，它们由悬浮在具有不同血细胞比容（5％和10％）的Dextran 40溶液中的绵羊红细胞（RBC）组成。实验在通过软光刻制造的聚二甲基硅氧烷（PDMS）微通道网络中进行。高速视频显微镜系统用于以10 µL / min的血流速度获得结果。该系统可以可视化气泡沿网络的形成和流动。结果表明，气泡的通过强烈影响细胞的局部浓度，因为在气泡的上游观察到较高的细胞浓度，而在气泡的下游区域观察到较低的局部血细胞比容。在分叉中，气泡可能不对称地分裂，导致流出分支之间的RBC分布不均匀。