Development and Evaluation of a PCV-Dependent Visual Hemolysis Color Scale for Packed Red Blood Cell Products.

Objective: To develop a PCV-dependent hemolysis color scale and evaluate its accuracy in predicting supernatant hemoglobin concentration in packed red blood cell (pRBC) products, helping to determine transfusion safety.

Design: Prospective experimental study.

Setting: University veterinary teaching hospital.

Interventions: Serial dilutions of a pRBC unit were performed to create a range of hemolyzed supernatant samples. A commercial graphics program was used to allocate computerized color to each hemolyzed sample, constructing a color scale. Study participants were then asked to use the color scale to estimate the hemoglobin concentration of a provided supernatant sample. The color estimation data were analyzed by the authors to determine whether to transfuse blood, as pRBC should not be transfused if the product's percentage hemolysis is >1%.

Measurements And Main Results: Visual inspection with the color scale was evaluated with seven supernatant test samples containing different free hemoglobin concentrations (0.3-8.0 g/L). The percentage of correct color estimation overall was 61.9%. The percentage of correct decisions to transfuse the blood product overall would have been 93.7%. All incorrect estimations were one color range (approximately 1.0 g/L difference between the ranges) off from the correct estimation for all samples.

Conclusions: The color scale aided the visual assessment of hemolysis. However, visual inspection with the color scale can still be inaccurate near the corresponding cutoff color of <1% hemolysis in each PCV range. If the supernatant color of the unit is estimated to be one color range off from the cutoff color, the cell-free hemoglobin concentration of the unit should be measured, and percentage hemolysis should be calculated to determine if it meets the <1% hemolysis standard.