Detection of blood coagulation in an extracorporeal circuit using magnetic and absorbance properties

Abstract

In extracorporeal circulation, intra-circuit blood coagulation can lead to serious problems. However, intra-circuit coagulation cannot be monitored in real-time and is only intermittently monitored by measuring the activated clotting time (ACT). As blood clotting progresses in a circuit, the color of the blood turns from bright red to dark red. And, changes in blood coagulation can be detected using devices with optical sensors because the absorbance is likely to change as blood coagulates. However, the absorbance may also increase when oxygen partial pressure is altered by artificial lungs. Thus, there is a need for a device that is not affected by blood oxygenation. Therefore, we used a magnet and a flux meter to assess changes in the magnetic force with blood coagulation. Thus, there is a need for a device that is not affected by blood oxygenation. Therefore, we used a magnet and a flux meter to assess changes in the magnetic force with blood coagulation. Measurements were made at different flux intensities to capture the magnetic flux changes during blood coagulation. Blood (100 ml) was stored in a beaker. Calcium chloride (CaCl2: 0.2 ml) was then added to the beaker to promote coagulation. Blood from the beaker was drawn into a syringe and set in the magnetic flux measurement fixture, and a magnet was fixed on top of the syringe for 24 min. The flux meter readings increased as the blood coagulated. The results suggest that it is possible to capture magnetic flux density changes during the process of blood coagulation. From the above may lead to the development of a device that monitors coagulation in extracorporeal circuits in real time by monitoring two aspects of the coagulation process: absorbance and magnetic flux density.