Microfluidic-Based Measurement Method of Red Blood Cell Aggregation under Hematocrit Variations

Area of Science:

• Biomedical Engineering
• Hematology
• Microfluidics

Background:

• Red blood cell (RBC) aggregation and erythrocyte sedimentation rate (ESR) are crucial for assessing blood rheology at low shear rates.
• Existing methods for measuring RBC aggregation may not adequately account for hematocrit variations during ESR.

Purpose of the Study:

• To develop and validate a microfluidic technique for evaluating RBC aggregation under dynamic hematocrit changes during ESR.
• To introduce a new index, the Erythrocyte-sedimentation-rate Aggregation Index (EAI), for quantifying RBC aggregation during ESR.

Main Methods:

• A microfluidic device utilizing a disposable suction pump and pinch valve was employed to control blood flow.
• Temporal variations in image intensity were used to calculate the EAI, reflecting RBC aggregation.
• The method was validated by varying hematocrit levels and testing aggregated and thermally-induced blood samples.

Main Results:

• The newly proposed EAI demonstrated significant sensitivity to hematocrit variations, unlike the conventional aggregation index (AI).
• The EAI effectively quantified changes in RBC aggregation under varying hematocrit conditions.
• The method successfully detected differences in RBC aggregation for aggregated and thermally-induced blood samples.

Conclusions:

• The microfluidic-based method and the EAI provide a robust approach for monitoring RBC aggregation during continuous hematocrit variations in ESR.
• The EAI is a more effective biomarker than the conventional AI for assessing RBC aggregation dynamics under ESR conditions.
• This technique holds promise for improved diagnostics and understanding of blood rheology in various physiological and pathological states.