Murashige Tomotaka, Sakota Daisuke, Kosaka Ryo, Nishida Masahiro, Kawaguchi Yasuo, Yamane Takashi, Maruyama Osamu
Graduate School of Science and Technology, Tokyo University of Science, Chiba, Japan.
National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
Artif Organs. 2016 Sep;40(9):856-66. doi: 10.1111/aor.12799.
Plasma skimming is a phenomenon in which discharge hematocrit is lower than feed hematocrit in microvessels. Plasma skimming has been investigated at a bearing gap in a spiral groove bearing (SGB), as this has the potential to prevent hemolysis in the SGB of a blood pump. However, it is not clear whether plasma skimming occurs in a blood pump with the SGB, because the hematocrit has not been obtained. The purpose of this study is to verify plasma skimming in an SGB of a centrifugal blood pump by developing a hematocrit measurement method in an SGB. Erythrocyte observation using a high-speed microscope and a bearing gap measurement using a laser confocal displacement meter was performed five times. In these tests, bovine blood as a working fluid was diluted with autologous plasma to adjust the hematocrit to 1.0%. A resistor was adjusted to achieve a pressure head of 100 mm Hg and a flow rate of 5.0 L/min at a rotational speed of 2800 rpm. Hematocrit on the ridge region in the SGB was measured using an image analysis based on motion image of erythrocytes, mean corpuscular volume, the measured bearing gap, and a cross-sectional area of erythrocyte. Mean hematocrit on the ridge region in the SGB was linearly reduced from 0.97 to 0.07% with the decreasing mean bearing gap from 38 to 21 μm when the rotational speed was changed from 2250 to 3000 rpm. A maximum plasma skimming efficiency of 93% was obtained with a gap of 21 μm. In conclusion, we succeeded in measuring the hematocrit on the ridge region in the SGB of the blood pump. Hematocrit decreased on the ridge region in the SGB and plasma skimming occurred with a bearing gap of less than 30 μm in the hydrodynamically levitated centrifugal blood pump.
血浆撇取是一种在微血管中排出的血细胞比容低于进料血细胞比容的现象。在螺旋槽轴承（SGB）的轴承间隙处对血浆撇取进行了研究，因为这有可能防止血泵的SGB中发生溶血。然而，尚不清楚在带有SGB的血泵中是否会发生血浆撇取，因为尚未获得血细胞比容数据。本研究的目的是通过开发一种在SGB中测量血细胞比容的方法，来验证离心血泵的SGB中是否存在血浆撇取现象。使用高速显微镜观察红细胞，并使用激光共聚焦位移计测量轴承间隙，共进行了五次。在这些测试中，将作为工作流体的牛血用自体血浆稀释，以将血细胞比容调整至1.0%。调节电阻器，以在2800转/分钟的转速下实现100毫米汞柱的压头和5.0升/分钟的流速。使用基于红细胞运动图像、平均红细胞体积、测量的轴承间隙和红细胞横截面积的图像分析，测量SGB中脊区域的血细胞比容。当转速从2250转/分钟变为3000转/分钟时，随着平均轴承间隙从38微米减小到21微米，SGB中脊区域的平均血细胞比容从0.97%线性降低至0.07%。在间隙为21微米时，获得了93%的最大血浆撇取效率。总之，我们成功测量了血泵SGB中脊区域的血细胞比容。在流体动力学悬浮离心血泵中，SGB的脊区域血细胞比容降低，且当轴承间隙小于30微米时会发生血浆撇取现象。
