Lipaemic plasma: An objective non-invasive photometric method to classify plasma turbidity and its association with red cell haemolysis.

Background and objectives: Plasma components are visually inspected, and non-transparent, turbid units are rejected for transfusion and fractionation. Additionally, in case a plasma component is deemed lipaemic, there is conflicting data on the accompanying red cell concentrate (RCC) in vitro quality. As visual inspection of plasma turbidity is a subjective method, we aimed to devise an objective measurement using a quick, non-invasive, table-top spectrophotometry-based method. Using this method, the correlation between spectrophotometric data and its predictive value on haemolysis of the accompanying RCC during storage was assessed.

Materials and methods: A total of 365 plasma units were visually inspected for turbidity and analysed for light reflection parameters (L*, a* and b*) and triglyceride (TG) levels. Leukoreduced RCCs in saline-adenine-glucose-mannitol (SAGM), prepared from the accompanying lipaemic whole blood, were stored for up to 6 weeks and analysed for quality parameters.

Results: The light reflection L* value was the most discriminating between clear and turbid/lipaemic plasma. Also, a correlation was found between TG levels and L* values (R² = 0.703). Plasma with TG ≥ 2.5 mmol/L showed an L* value >50 with >90% specificity and sensitivity. RCC from donations with a plasma L* value ≥68 showed significantly higher haemolysis levels (p < 0.05) during storage.

Conclusion: The non-invasive photometric analysis of plasma turbidity correlated both with visual inspection and plasma TG levels. Measurement of L* values of plasma may be helpful in identifying donations with high TG levels and higher risk for increased haemolysis during RCC storage.