Kang Yang Jun
Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju, South Korea.
Biomicrofluidics. 2018 Apr 9;12(2):024116. doi: 10.1063/1.5017052. eCollection 2018 Mar.
To evaluate variations of blood circulating in closed loops, hemorheological properties including blood viscosity and red blood cells (RBCs) are quantitatively measured with independent in-vitro instruments after collecting blood from a closed loop. But, most previous methods require periodic blood collections which induce several problems such as geometric differences between the fluidic channel and the in-vitro method, hemodilution, storage time, and unspecific blood flow rates. To resolve these issues, in this study, blood viscosity and RBC aggregation of blood circulating within a closed loop are measured with a microfluidic platform periodically and simultaneously. To demonstrate the proposed method, closed-loop circulation is established by connecting several components (peristaltic pump, air compliance unit, fluid divider, and reservoir) in series. In addition, to measure blood viscosity and RBC aggregation, a microfluidic platform composed of a microfluidic device, pinch valve, and syringe pump is created. During each period, blood viscosity and RBC aggregation are measured by monitoring blood flow at constant blood flow, and image intensity at stationary blood flow. The proposed method is first employed to evaluate the effect of hematocrits and dextran concentrations on the RBC aggregation and blood viscosity by using a syringe pump (i.e., specific blood flow-rate). The method is then applied to detect the blood viscosity and RBC aggregation under closed-loop circulation (i.e., unspecific blood flow-rate). From these experimental demonstrations, it is found that the suggested method can be effectively used to monitor the RBC aggregation and blood viscosity under closed-loop circulation. Since this method does not require periodic collection from closed-loop circulation or an additional procedure for estimating blood flow-rate with a syringe pump, it will be effectively used to monitor variations of blood circulating in extracorporeal bypass loops.
为了评估闭环中循环血液的变化，在从闭环采集血液后，使用独立的体外仪器对包括血液粘度和红细胞（RBC）在内的血液流变学特性进行定量测量。但是，大多数先前的方法需要定期采集血液，这会引发一些问题，如流体通道与体外方法之间的几何差异、血液稀释、储存时间以及非特定的血流速率。为了解决这些问题，在本研究中，使用微流控平台定期同时测量闭环内循环血液的血液粘度和RBC聚集。为了证明所提出的方法，通过串联连接几个组件（蠕动泵、空气顺应性单元、流体分配器和储液器）建立闭环循环。此外，为了测量血液粘度和RBC聚集，创建了一个由微流控装置、夹管阀和注射泵组成的微流控平台。在每个时间段内，通过在恒定血流下监测血流以及在静态血流下监测图像强度来测量血液粘度和RBC聚集。所提出的方法首先用于通过使用注射泵（即特定血流速率）评估血细胞比容和右旋糖酐浓度对RBC聚集和血液粘度的影响。然后将该方法应用于检测闭环循环下（即非特定血流速率）的血液粘度和RBC聚集。从这些实验演示中发现，所建议的方法可以有效地用于监测闭环循环下的RBC聚集和血液粘度。由于该方法不需要从闭环循环中定期采集血液或使用注射泵估计血流速率的额外程序，因此它将有效地用于监测体外旁路循环中循环血液的变化。
