Hijikata Wataru, Maruyama Takuro, Suzumori Yuki, Shinshi Tadahiko
1 School of Engineering, Tokyo Institute of Technology, Tokyo, Japan.
2 Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.
Proc Inst Mech Eng H. 2019 May;233(5):562-569. doi: 10.1177/0954411919838738. Epub 2019 Mar 20.
Ventricular assist devices assist in blood circulation and form a crucial component of artificial hearts. While it is important to measure parameters such as the flow rate, pressure head and viscosity of the blood, implanting additional devices to do such measurements is inadvisable. To this end, we demonstrate the adaptation of a ventricular assist device for the purpose of measuring blood viscosity. Such an approach eliminates the need for additional dedicated viscometers in artificial hearts. In the proposed method, the blood viscosity is measured by applying radial vibrational excitation to the impeller in a ventricular assist device using its magnetic levitation system. During the measurement, blood is exposed to a combination of a low shear rate (≈100/s) generated by the radial vibration of the impeller and a high shear rate (>10,000/s) generated by the impeller's rotation. The apparent viscosity of blood depends on the shear rate, so we determined which shear rate was the dominant one in the proposed method. The measurement results showed that the viscosity measured by the proposed method was in good agreement with the reference viscosity measured with a high shear rate. The mean absolute deviation in the measurements using the proposed method and those obtained using a concentric cylindrical viscometer at a high shear rate was 0.12 mPa s for four samples of porcine blood, with viscosities ranging from 2.32 to 2.75 mPa s.
心室辅助装置有助于血液循环，是人工心脏的关键组成部分。虽然测量诸如血流量、压头和血液粘度等参数很重要，但植入额外的装置来进行此类测量并不可取。为此，我们展示了一种用于测量血液粘度的心室辅助装置的改装。这种方法消除了人工心脏中额外专用粘度计的需求。在所提出的方法中，利用心室辅助装置中的磁悬浮系统对叶轮施加径向振动激励来测量血液粘度。在测量过程中，血液会受到叶轮径向振动产生的低剪切速率（≈100/s）和叶轮旋转产生的高剪切速率（>10,000/s）的综合作用。血液的表观粘度取决于剪切速率，因此我们确定了在所提出的方法中哪种剪切速率起主导作用。测量结果表明，所提出的方法测量的粘度与高剪切速率下测量的参考粘度吻合良好。对于四个猪血样本，在所提出的方法测量值与使用同心圆柱粘度计在高剪切速率下测量值之间的平均绝对偏差为0.12 mPa·s，这些样本的粘度范围为2.32至2.75 mPa·s。
