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Proceedings Paper

Measurement of cardiac output using near-infrared heating of blood
Author(s): Michael G. Curley; Patrick S. Hamilton; Joseph T. Walsh
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Paper Abstract

Thermodilution-based cardiac output measurements are made using iced saline or blood heated by resistive heating as a dilutable indicator. Because near-infrared irradiation penetrates sufficiently deeply into blood, it can safely deposit up to six times the energy of a resistive heater, improving the accuracy of the measurements while continuously monitoring cardiac output. We have developed a prototype system using 980 nm diode lasers to irradiate blood through a diffuser. This system was tested using an optical blood phantom and was compared to iced-saline injection and resistive heating. Three flow estimates were made at each of 18 combinations of stroke rate, stroke volume, and systole/diastole ratios. Accuracy was determined by the quality of the fit between the estimated flows and the actual flow. Reproducibility was determined by the normalized standard deviation. Results: Measurements made by saline injection were the most accurate (R2 equals 0.982) and reproducible (NSD equals 2.8%). Power limitations on the resistive heating to ensure a safe blood temperature limited its accuracy (R2 equals 0.537) and reproducibility (NSD equals 18.1%). Laser-based heating showed reasonable accuracy and reproducibility (R2 equals 0.950, NSD equals 7.8%). Laser heating thus represents a potentially more accurate alternative to saline injection for cardiac output measurement than does resistive heating.

Paper Details

Date Published: 22 May 1997
PDF: 11 pages
Proc. SPIE 2970, Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VII, (22 May 1997); doi: 10.1117/12.275080
Show Author Affiliations
Michael G. Curley, E.P. Ltd. (United States)
Patrick S. Hamilton, E.P. Ltd. (United States)
Joseph T. Walsh, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 2970:
Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VII
R. Rox Anderson; Harvey Lui; Michail M. Pankratov; Kenneth Eugene Bartels; Gerhard J. Mueller; Graham M. Watson; Reza S. Malek; Lawrence S. Bass; Lloyd P. Tate; Hans-Dieter Reidenbach; Kenneth Eugene Bartels; R. Rox Anderson; Lawrence S. Bass; Aaron P. Perlmutter; Kenton W. Gregory; David M. Harris; David M. Harris; Harvey Lui; Reza S. Malek; Gerhard J. Mueller; Michail M. Pankratov; Aaron P. Perlmutter; Hans-Dieter Reidenbach; Lloyd P. Tate; Graham M. Watson, Editor(s)

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