Noninvasive monitoring of tissue hemoglobin using UV-VIS diffuse reflectance spectroscopy: a pilot study.
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We conducted a pilot study on 10 patients undergoing general surgery to test the feasibility of diffuse reflectance spectroscopy in the visible wavelength range as a noninvasive monitoring tool for blood loss during surgery. Ratios of raw diffuse reflectance at wavelength pairs were tested as a first-pass for estimating hemoglobin concentration. Ratios can be calculated easily and rapidly with limited post-processing, and so this can be considered a near real-time monitoring device. We found the best hemoglobin correlations were when ratios at isosbestic points of oxy- and deoxyhemoglobin were used, specifically 529/500 nm. Baseline subtraction improved correlations, specifically at 520/509 nm. These results demonstrate proof-of-concept for the ability of this noninvasive device to monitor hemoglobin concentration changes due to surgical blood loss. The 529/500 nm ratio also appears to account for variations in probe pressure, as determined from measurements on two volunteers.
Blood Chemical Analysis
Blood Loss, Surgical
Reproducibility of Results
Sensitivity and Specificity
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Robert W. Carr, Jr., Professor of Biomedical Engineering
Dr. Ramanujam is the Robert W. Carr Professor of Biomedical Engineering, and also a faculty member in the Global Health Institute and Dept. Pharmacology and Cell Biology at Duke University. She is an innovator, educator and entrepreneur and her mission is to develop and leverage technology to have the most wide reaching impact in women’s health. She directs the center for Global Women’s Health Technologies (GWHT), a partnership between the Pratt School of Engineering and the Duke