Connector sensors for permittivity-based thrombus monitoring in extracorporeal life support

Bioimpedance Analysis as Early Predictor for Clot Formation Inside a Blood-Perfused Test Chamber: Proof of Concept Using an In Vitro Test-Circuit

“…Hayashi et al investigated the dielectric response of static blood coagulation with human blood and established a proof of concept that DBCM can sensitively measure blood coagulation by detecting an increase in permittivity caused by red blood cell aggregation [ 18 ]. Sifuna et al investigated the utilization of DBCM for permittivity-based clot monitoring by integrating a connector sensor into a dynamic circuit in which swine blood circulated and compared its clot detecting capabilities with optical coherence tomography imaging [ 19 ]. The main difference to our study regarding the experimental setup was that we directly compared impedance analysis with pressure difference measurement for the first time.…”

“…In our test circuit, the test chamber was more susceptible to occlusion by blood clots compared to MO. Furthermore, studies have shown that hematocrit also affects bioimpedance analysis [ 18 , 19 ]. Another limitation of this study is that the test chambers containing the titanium fibers for impedance measurement were all made by hand; therefore, the effects of contamination and residues on the fibers cannot be ruled out entirely.…”

“…In a frequency range of 100 Hz to 100 MHz, this results in an observable change in permittivity [ 18 ]. Sifuna et al investigated not only the static but also the dynamic changes in permittivity properties in flowing blood in the frequency range around 100 KHz to 10 MHz and observed an increase in permittivity dependent on time and the coagulation progress [ 19 ]. These preceding studies suggest a correlation between coagulation and permittivity changes, thus forming the basis for the possible use of bioimpedance analysis to detect clot formation inside a MO [ 18 , 19 ].…”

“…Sifuna et al investigated not only the static but also the dynamic changes in permittivity properties in flowing blood in the frequency range around 100 KHz to 10 MHz and observed an increase in permittivity dependent on time and the coagulation progress [ 19 ]. These preceding studies suggest a correlation between coagulation and permittivity changes, thus forming the basis for the possible use of bioimpedance analysis to detect clot formation inside a MO [ 18 , 19 ]. Based on the results of these preceding studies that established a proof of concept for bioimpedance analysis for clot detection, an experimental dynamic test circuit was constructed integrating bioimpedance analysis and pressure difference measurement in one test circuit for the first time.…”