Monitoring of thrombus formation in mock extracorporeal circulation system using electrical impedance spectroscopy

Extracorporeal blood flow devices such as artificial ventricular assistance devices, heart-lung machines, and etc. are widely used in clinic medicine for many years. However, the thrombus formation is still a major concern for these devices. Hence, thrombus real-time monitoring is very essential in these devices. Currently, there are few studies based on optical, ultrasonic and electrical measurement principles for the real-time thrombus detection in the extracorporeal blood flow circulation. The red blood cells (RBCs) concentration has been measured by using the optical measurement method. However, the optical measurement for thrombus formation is impossible in the case of various biocompatible coating in the channel wall. Additionally, the ultrasonic method has some inherent limitation such as the inability to differentiate air emboli from thrombus. The electrical method seems better alternative to the both methods. Asakura et al. reported thrombus formation detection using permittivity measurement. However, the permittivity based detection has frequency sensitivity. Determining a suitable frequency range for each application is a difficult task as it depends upon the samples and the nature of the progress of the thrombus formation process. Cole-Cole analysis is the method to analyzer properties of blood on whole frequency range by using four parameters of the relaxation frequency, the resistance at zero frequency, the resistance at infinite frequency, and shape factor. In this study, thrombus formation results of the thrombus formation experiment in flowing condition were reported. To compare with the present blood coagulability measurement, Activated Clotting Time (ACT) result was also reported. Additionally, temporal change in coagulation factor fibrinogen quantity was represented to consider its effects on thrombus formation results.