Optical properties of human whole blood - Changes due to slow heating

• Optical properties of human whole blood were measured in vitro, at 633 nm with a double integrating sphere set-up, The blood was kept at constant flow through a flow cell while slowly heating the blood from approximately 25 degrees C to 55 degrees C in a heat exchanger, The results show a small but distinct decrease in the g-factor of 1.7 +/- 0.6\% and a similar increase in the scattering coefficient, mu(s), of 2.9 +/- 0.6\% at approximately 45-46 degrees C. When studying the thermal effect on the blood cells under a white-light transmission microscope, the changes in the scattering properties could be correlated to a sudden change in the shape of the red blood cells, from disc-shaped to spherical, at approximately the same temperature. Furthermore, a continuous manifest increase in the absorption coefficient, mu(a), was seen with temperature rise, on average 83.8 +/- 68.1\% when reaching the temperature 50 degrees C. This might be due to heat-induced haemolysis of the red blood cells, resulting in free light absorbing haemoglobin in the surrounding plasma and thus higher effective light absorption.

Ämnesord

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

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