Journal of Theoretical Medicine
Volume 6 (2005), Issue 3, Pages 161-172
doi:10.1080/10273660500158712

A Numerical Investigation of Heat Transfer Cardiac Output Measurements

P. Fotheringham,1 A. R. Gourlay,1 S. Mckee,2 and S. Andrews3

1Centre for Mathematical and Computational Science in Medicine, University of Glasgow, Glasgow G12 8QQ, UK
2Department of Mathematics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK
3AorTech International plc., Strathclyde Business Park, Bellshill, Lanarkshire ML4 3NJ, UK

Received 18 December 2002; Revised 10 December 2003; Accepted 31 March 2005

Copyright © 2005 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Measurement of cardiac output is often investigated using a technique based on hot-film anemometry. Here, we discuss a modification to hot-film anemometry, which involves a cylindrical heating element mounted flush on the surface of a typical Swan-Ganz catheter. In contrast to traditional thermodilution, the method discussed here has the potential to allow continuous monitoring of cardiac output.

This paper demonstrates that there is a simple approximate relationship between the power input to the device to maintain a temperature of one degree above blood heat and cardiac output. Since, the heat transfer and the fluid flow decouple, a numerical model of the heat transfer of a cylindrical catheter (with heating element) sitting concentrically within a rigid cylindrical artery is developed. Numerical results were obtained for a wide selection of flow profiles, including experimental data. The results indicate that the cardiac output/power input relationship is extremely robust with respect to flow profile and system parameter variation.