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A1688
October 22, 2008 9:00 AM - 11:00 AM Room Hall E2-Area G, |
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| Non-Invasive and Direct Determination of Hemoglobin in Native Blood Present in Sampling Tubes | ||||||||||||||||||||||||||||||||||||||||||||||||
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Alexander Opp, M.S., Sebastian Look, Leif Dibbelt, Ph.D., Soehnke Boye, M.D., Hartmut Gehring, M.D., Ph.D. Institute of Medical Engineering, University of Luebeck, Luebeck, Germany |
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Introduction: The corpuscular concentration of hemoglobin (ctHb) determines the capacity of human blood to distribute oxygen to the body and is thus a critical laboratory marker. Current assays measure ctHb by hemolyzing the erythrocytes of a distinct sample and chemically converting all Hb species in the hemolysate to a unique, strongly absorbing derivative; they therefore are invasive, laborious and time-consuming. A fast, non-invasive, reagent- free photometric method of hemoglobin concentration (ctHb) measurement was developed for utilization on tubes. With respect to the physiological range of ctHb, the procedure should cover the concentration between 70 g/L and 170 g/L ctHb. For this measurement procedure either lasers or light emitting diodes (LEDs) can be used. In the present investigation we introduce an optical sensor based on LEDs which is designed to measure in a tube and can therefore be used in clinical areas, where blood is taken from the body via a drainage system such as during blood donations. Method: The measurement utilizes two wavelengths in the infrared range around the isosbestic points of the oxy- and deoxyhemoglobin absorption curves, at 800nm and 1300nm (1). Once the sensor is attached to the sample tube, two photodiodes located opposite the LEDs, measure the amount of light absorbed by the respective blood. To eliminate interferences caused by the sample tube, a first measurement is taken with an empty tube to provide a baseline calibration; the second measurement taken from the same tube filled with blood provides information of the actual ctHb. A number N of commercially available tubes (MacoPharma, France) and a 50 mL perfusor syringe as blood reservoir were used for each of the five different hemoglobin concentrations prepared by appropriately mixing plasma and erythrocyte concentrate. Sensor data were compared to results obtained from calibrated industry-standard analyzers. The reference values shown below is the arithmetic mean of five different samples taken invasively and measured by three hemoglobin analyzers (Hb 201+, Hemocue; Grossostheim, Germany) and two blood gas analyzers (OSM3, Radiometer; Copenhagen, Denmark). Results:[figure1]Figure 1: Measured hemoglobin concentrations compared to the reference concentrations with standard deviations.[table1]Discussion: The ctHb values measured with the optical LED sensor achieved standard deviations comparable to those of the reference values (Table 1). The measuring range of the sensor covers concentrations up to 150 g/L ctHb. References: 1) Roggan et al: Optical Properties of Circulating Human Blood in the Wavelength Range 400 – 2500 nm. Journal of Biomedical Optics 4(1), 36-46 ( Jan. 1999). Anesthesiology 2008; 109 A1688 |
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Figure 1
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