Permittivity Measurement for Thrombus Detecting at Connector Gap in Extracorporeal Blood Circulating System

Abstract

Background Connector gap, a gap between connector and tube, is where very easily to occur thrombus formation in extracorporeal blood circulating system. Objective The aim of this study is to develop a system to detect thrombus formed at the connector gap in an extracorporeal blood circulating system and evaluate it. Method The bio-mate flow path incorporating the connector electrode is filled with fresh porcine blood and circulated by a centrifugal pump. Calcium chloride and sodium citrate are added to the circulating system to adjust ACT (Activated clotting time) to be around 160 s. In the case that the thrombus formation detected by permittivity measurement, heparin is added to stop the coagulation reaction, and the measurement is terminated. Results Thrombus parameter is not affected by ACT change or drug addition and it increased to 20% at the end of the experiment, which confirms the feasibility of the proposed thrombus detecting sensor. As thrombus is not confirmed in extracorporeal blood circulating system besides the connector gap, it is considered to be the early stage of thrombus formation. Since thrombus formation is made on the end face b and large regardless of the position of the electrode, the promotion of thrombus formation by electrical measurement is not observed.