Two wavelengths Hematocrit Monitoring by Light Transmittance Method

Abstract

Methods for measuring the hematocrit level of whole blood includes measuring transmittance light at multiple wavelengths within the visible and infrared spectrum, calculating light transmittance at each of the multiple wavelengths, performing a comparison in a change in light transmittance between the multiple wavelengths, and comparison to total hematocrit value. A system for measuring total hematocrit of whole blood may include discrete LEDs for light source in the range of 430 nm to 950 nm, one photo detector, data processing circuitry, and/or a display unit. We constructed a simplified system and probe, design with LEDs and a photodiode was placed at the other side of the finger, we compare the results of the system with hematocrit levels measured by centrifuge that using blood sample drawn from 120 patients. From our analysis, the wavelengths between 700 nm to 950 nm are insensitivity to hematocrit levels, and between 470 nm to 610 nm are sensitivity to hematocrit levels. The potential optimal wavelengths for light transmittance hematocrit measuring system are in the range of 700 nm-900 nm and 470 nm-610 nm. Then, we used two potential optimal LEDs wavelengths at 585 nm and 875nm for linear algorithm to design of the noninvasive hematocrit measuring system, from the acquired information the system able to predict the hematocrit value to obtained 90% of the 120 data is given an error less than 25%.