Noninvasive monitoring of tissue hemoglobin using UV-VIS diffuse reflectance spectroscopy: a pilot study.


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.







Eugene William Moretti

Professor of Anesthesiology

Research efforts are focused primarily in the area of functional genomics. Work has centered on investigating genetic polymorphisms in the surgical intensive care population that would predispose one to the development of the sepsis syndrome. As an extension of this work, there is ongoing investigation working to identify genetically susceptible populations at risk for developing various types of perioperative organ dysfunction. Parallel studies involve identification of a panel of biomarkers that would enable early diagnosis and intervention for those patients, both surgical and non-surgical that develop the sepsis syndrome. There is also active investigation in the human pharmacology laboratory in the department of anesthesiology involving the phase 1 testing of novel pharmaceutical agents in healthy volunteers.

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