Evaluation of optical propagation in blood for noninvasive detection of prethrombus blood condition.

: This article evaluates the optical propagation to detect a "prethrombus" blood noninvasively. Thrombosis is still an inevitable issue in use of blood pumps, and it is required to predict thrombus formation as early as possible. We focused on the red blood cell (RBC) aggregation that is one of the features of thrombogenic process. First, by using a computer simulation, we calculated the optical propagations in blood for the RBC aggregation and nonaggregation blood. This simulation is based on the Monte-Carlo method and attempts to calculate the optical characteristics of the blood stochastically. In our simulation, the optical propagation with the RBC aggregation showed a different characteristic from that of the nonaggregation. Next, we examined the optical propagation in bovine blood with various activated whole blood clotting time (ACT). The blood mixed with sodium citrate was circulated by a blood pump. The ACT was adjusted between 1,000 and 50 seconds by controlling the ratio of calcium chloride solution to sodium citrate. We confirmed the RBC aggregation by using microscopic images and microthromboses in the pump directly. As a result, we evaluated that the change of the optical propagation has a correlation with thrombogenic process just as it was observed in our computer simulation. Our data indicate that the measurement of optical propagation can detect a prethrombous blood condition with RBC aggregation. Our study will help to establish optical technologies to detect prethrombous continuously and noninvasively.