Simultaneous measurement of blood pressure and RBC aggregation by monitoring on–off blood flows supplied from a disposable air-compressed pump

Abstract

Haematological diseases significantly increase RBC aggregation. Specifically, RBC aggregation is considerably varied by haematological factors including cellular properties, and suspending medium properties. Thus, in order to ensure consistent measurement of RBC aggregation, it is necessary to measure RBC aggregation and blood pressure simultaneously. Here, a method for simultaneously measuring RBC aggregation and blood pressure is demonstrated by analyzing blood flows supplied from a disposable air-compressed pump. A microfluidic device is composed of two parallel microfluidic channels (i.e., PBS channel and blood channel), an inlet, and outlets. After the PBS channel is filled with the PBS solution, the outlets of the PBS channel are completely closed with two pinch valves. Under varying blood flow rates of the disposable pump, the blood pressure index (PI) is quantified by analyzing the image intensity of RBCs in the PBS channel. Thereafter, at stasis, the RBC aggregation index (AI) is calculated by analyzing the image intensity of blood in the blood channel. First, under a constant blood flow-rate of a syringe pump, the image intensity of RBCs collected in the PBS channel (I_PC) is linearly proportional to blood pressure estimated in the blood channel (P_BC). Second, with respect to variations in the blood flow-rate of the proposed pump, the I_PC and P_BC decrease gradually over time. Two blood pressure indices (PI [P_BC], and PI [I_PC]) are obtained by averaging temporal variations in the P_BC and I_PC, respectively. The results of the regression analysis indicate that the coefficient of the linear regression yields a higher value of R² = 0.9051. Subsequently, the PI (I_PC) is effectively used to estimate blood pressure. Finally, the variations in blood pressure and RBC aggregation are obtained by using aggregation-enhanced blood samples and deformability-reduced blood samples. Thus, the proposed method leads to consistent variations in the PI and AI, when compared with the previous results. The experimental demonstrations indicate that two indices (PI and AI) are effectively used to simultaneously quantify blood pressure and RBC aggregation.