To achieve the quantitative optical non-invasive diagnosis of blood during extracorporeal circulation therapies, the instrumental technique to extract extracellular spectra from whole blood was developed. In the circuit, the continuous blood flow was generated by a centrifugal blood pump. The oxygen saturation was maintained 100% by an oxygenator. The developed glass optical flow cell was attached to the outlet tubing of the oxygenator. The halogen lamp including the light from 400 to 900 nm wavelength was used for the light source. The light was guided into an optical fiber. The light emitted by the fiber was collimated and emitted to the flow cell flat surface at the incident angle of 45 degrees. The light just reflected on the boundary between inner surface of the flow cell and plasma at 45 degrees was detected by the detection fiber. The detected light was analyzed by a spectral photometer. The obtained spectrum from 400 to 600nm wavelength was not changed with respect to the hematocrit. In contrast, the signal in the spectral range was changed when the plasma free hemoglobin increased. By using two spectral range, 505±5 nm and 542.5±2.5 nm, the differential spectrum was correlated with the free hemoglobin at R²=0.99. On the other hand, as for the hematocrit, the differential spectrum was not correlated at R²=0.01. Finally, the plasma free hemoglobin was quantified with the accuracy of 22±19mg/dL. The result shows that the developed plasma surface reflectance spectroscopy (PSRS) can extract the plasma spectrum from flowing whole blood.

Date Published: 9 May 2012
PDF: 6 pages
Proc. SPIE 8439, Optical Sensing and Detection II, 84392K (9 May 2012); doi: 10.1117/12.921331

Published in SPIE Proceedings Vol. 8439:
Optical Sensing and Detection II
Francis Berghmans; Anna Grazia Mignani; Piet De Moor, Editor(s)