Dobbe Johannes G G, Streekstra Geert J, Strackee Jan, Rutten Marcel C M, Stijnen Johannes M A, Grimbergen Cornelis A
Department of Medical Technological Development, Academic Medical Center. University of Amsterdam, P.O. Box 22700, 1 100 DE Amsterdam, The Netherlands.
IEEE Trans Biomed Eng. 2003 Jan;50(1):97-106. doi: 10.1109/TBME.2002.807319.
Syllectometry is a measuring method that is commonly used to assess red blood cell (RBC) aggregability. In syllectometry, light is incident on a layer of whole blood initially exposed to shear flow. The backscattered light is measured after abruptly stopping the driving mechanism. The resultant time-dependent intensity plot is called the syllectogram. Parameters that quantify RBC aggregability are obtained by analyzing the syllectogram. As we will show in this paper, the upstroke in the initial part of the syllectogram contains the information for measurement of RBC-shape recovery in whole blood as well. To estimate RBC-shape recovery, we extended the existing two-exponential mathematical representation of the syllectogram by a third exponent that describes the upstroke. To investigate the feasibility of RBC-shape recovery measurement from the upstroke, we derived an analytical model of the flow decay that follows after abruptly stopping the driving mechanism. The model reveals that for large gaps the flow decay may interfere with the true RBC-shape recovery process. These theoretical findings were confirmed by velocity measurements in a Couette-type aggregometer. Syllectograms obtained using large gaps differ in many respects from those obtained using small gaps. As predicted by our model large gaps show a prolonged apparent shape-recovery time-constant. Moreover, a delayed intensity peak, a reduced upstroke of the intensity peak and a considerable increase of the half-life parameter are observed. The aggregation indices for large gaps are lower than for small gaps. This paper yields a better understanding of the velocity and shear-rate decay following upon abruptly stopping the driving mechanism. A better mathematical representation of the syllectogram and recommendations for a maximum gap width enables both RBC-shape recovery and aggregation measurements in whole blood using syllectometry.
血细胞聚集测量法是一种常用于评估红细胞（RBC）聚集性的测量方法。在血细胞聚集测量法中，光线入射到最初暴露于剪切流的全血层上。在突然停止驱动机制后测量反向散射光。所得的随时间变化的强度图称为血细胞聚集图。通过分析血细胞聚集图可获得量化红细胞聚集性的参数。正如我们将在本文中展示的，血细胞聚集图初始部分的上升段也包含了全血中红细胞形状恢复测量的信息。为了估计红细胞形状恢复情况，我们通过描述上升段的第三个指数扩展了现有的血细胞聚集图的双指数数学表示。为了研究从上升段测量红细胞形状恢复的可行性，我们推导了驱动机制突然停止后流动衰减的解析模型。该模型表明，对于较大间隙，流动衰减可能会干扰真正的红细胞形状恢复过程。这些理论发现通过在库埃特型聚集仪中的速度测量得到了证实。使用大间隙获得的血细胞聚集图在许多方面与使用小间隙获得的不同。正如我们的模型所预测的，大间隙显示出明显更长的形状恢复时间常数。此外，还观察到强度峰值延迟、强度峰值上升段减小以及半衰期参数显著增加。大间隙的聚集指数低于小间隙。本文有助于更好地理解驱动机制突然停止后的速度和剪切速率衰减。对血细胞聚集图进行更好的数学表示以及对最大间隙宽度的建议，使得能够使用血细胞聚集测量法在全血中同时进行红细胞形状恢复和聚集测量。
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