Blood flow rate measurement using intravascular heat-exchange catheter

Abstract

During treatments for patients with coronary artery diseases, continuous cardiac out measurement is essential to provide feedback and monitor any improvements in the vascular system. This paper presents a new possible approach to measure the cardiac output using an intravascular heatexchange catheter. In order to measure the blood flow rate, the catheter is inserted into a blood vessel and a heat-transfer element attached at the distal end is positioned at a desired location to enable heat transfer from the blood to the cooling fluid in the element. The outlet temperature change of the cooling fluid occurs during the heat-exchange process and is monitored by thermal-sensors to determine the cardiac output and any substantial change of the cardiac output. A preliminary experimental study demonstrated an essential relationship, which can be used to determine the cardiac output from the measurement of the outlet temperature of the cooling fluid alone, without the need to determine the temperature change at the down stream of the blood flow. It also has an advantage of not injecting any auxiliary liquid or dye into the blood flow. Thus, it allows repeated measurement and does not affect the composition of blood stream. Furthermore, it does not warm up the blood flow. Therefore, it avoids any possible adverse effects caused by heating in the vascular system. This current approach is useful in monitoring any continuous improvement and providing feedback in the stenting surgery operation, bypass operation or any treatment related to atherosclerosis.