Analyzing the efficiency of the colorimetric technique in determining the degree of hemolysis of stored blood

Transfusion has risks of adverse outcomes on patients due to the storage lesions of blood products. Measuring quality of the blood prior to usage can minimize the transfusion related reactions. For controlling the quality of units, experts visually assess the degree of hemolysis by comparing color of blood with graded color charts. Since results are subjective and depend on the spectral energy distribution of the illuminant, the method is inaccurate. Instead of using color charts, color of the stored blood can quantitatively be measured by analyzing the spectrum of the light re flected from the sample with a spectrometer. The color of blood can be defi ned as a set of tristimulus values or color coordinates in the color space. In this study daily changes in the colorimetric parameters of stored blood were monitored and correlated with the changes in the degree of hemolysis. Red blood cell (RBC) suspensions collected from 7 male volunteers were used for the study. On each day of storage, 24 colorimetric parameters in various color spaces were measured with a re flection probe that transmits both the incident light from the light source to the blood bag; and the refl ected light from the blood bag to the spectrometer. Standard hemolysis measurements with Harboe technique were performed on weekly basis, by taking blood samples from blood bags. Colorimetric parameters: tristimulus X, u', u-v saturation, Hunter a, CIE a*, CIELAB chroma and the correlated color temperature (CCT) changed signifi cantly (p<0.05) for each sample after the 3rd week of storage. Except CCT, hemolysis showed good correlation (r>0.65) with the parameters that mostly correspond to red contents of the color stimuli. Hunter a apparently is the most suitable parameter for determining the degree of hemolysis with (r=0.71) (p<0.005).