Rouffiac Valérie, Peronneau Pierre, Guglielmi Jean-Paul, Del-Pino Muriel, Lassau Nathalie, Levenson Jaime
Laboratoires Innothera, Arcueil, France.
Ultrasound Med Biol. 2003 Jun;29(6):789-99. doi: 10.1016/s0301-5629(03)00033-4.
We have previously established new ultrasonic indexes for erythrocyte aggregation using a Couette device, and validated them toward the Rayleigh's theory and reproducibility. Two hydrodynamic protocols were applied on various suspensions and their aggregation degrees were characterized by: 1. for the decreasing shear rates protocol: the power P(US) at the nominal frequency of the transducer used; 2. for the kinetic protocol: aggregation times (latency and half-rise times), variation between initial disaggregated state (Vo) and final aggregated state (V(inf)) and AI(US), which is the integral of the kinetic curve over time. The objective of the present study was to demonstrate the ability of these indexes to characterize the aggregation dynamics of suspensions with various levels of aggregation induced by concentrations of dextran 70 kD (Dx) of 10, 20 and 40 g/L added to washed red cells resuspended in saline solution. The results showed a maximum of backscattered power (P(US)) for Dx = 40 g/L with the decreasing shear rates protocol. We measured a final aggregation level (V(inf)), a minimal aggregation time (T(m)) and a maximal value of AI(US) for Dx = 40 g/L with the aggregation kinetics protocol. On the other hand, viscosity is increased with dextran concentration. These evolutions of the ultrasound (US) indexes and viscosity with dextran concentrations are consistent with literature reports. In addition, a particularly interesting phenomenon of US backscattering enhancement was observed for kinetics with no null final shear rate, which has never before been reported in such a precise manner. By another way, each of the dextran suspensions was tested on the laser erythroaggregometer that is presently considered as the "gold standard" method for erythrocyte characterization. The laser indexes (aggregation time T(a), aggregation indexes AI(10s) and AI(60s)), deduced from a kinetic protocol, have similar significance to the US ones. Statistical comparisons have been done between laser and ultrasonic indexes and significant correlations (0.001 < p < 0.01) were obtained. The set of results allowed us to conclude that ultrasonic indexes are suitable markers for the erythrocyte aggregation.
我们之前使用库埃特装置建立了用于红细胞聚集的新超声指标，并根据瑞利理论和可重复性对其进行了验证。在各种悬浮液上应用了两种流体动力学方案，其聚集程度通过以下方式表征：1. 对于剪切速率降低方案：所用换能器标称频率下的功率P(US)；2. 对于动力学方案：聚集时间（延迟时间和半上升时间）、初始解聚状态(Vo)和最终聚集状态(V(inf))之间的变化以及AI(US)，AI(US)是动力学曲线随时间的积分。本研究的目的是证明这些指标能够表征添加了10、20和40 g/L的70 kD右旋糖酐（Dx）浓度的悬浮液在不同聚集水平下的聚集动力学，这些悬浮液添加到重悬于盐溶液中的洗涤红细胞中。结果表明，在剪切速率降低方案中，Dx = 40 g/L时反向散射功率（P(US)）最大。在聚集动力学方案中，我们测量了Dx = 40 g/L时的最终聚集水平（V(inf)）、最小聚集时间（T(m)）和AI(US)的最大值。另一方面，粘度随右旋糖酐浓度增加。超声（US）指标和粘度随右旋糖酐浓度的这些变化与文献报道一致。此外，对于最终剪切速率不为零的动力学，观察到了一种特别有趣的超声反向散射增强现象，此前从未以如此精确的方式报道过。另一方面，在目前被视为红细胞表征“金标准”方法的激光红细胞聚集仪上对每种右旋糖酐悬浮液进行了测试。从动力学方案推导的激光指标（聚集时间T(a)、聚集指数AI(10s)和AI(60s)）与超声指标具有相似的意义，并对激光指标和超声指标进行了统计比较，获得了显著相关性（0.001 < p < 0.01）。这组结果使我们得出结论：超声指标是红细胞聚集的合适标志物
