# Simulated Oxygen Supply Efficiency Assessment to Represent Stored Red Blood Cells Quality

## TL;DR

This study introduces a new method to assess the quality of stored red blood cells by evaluating their oxygen supply efficiency using parameters like oxygen affinity and the Bohr effect.

## Contribution

The novel contribution is a parameter system integrating oxygen affinity, cooperativity, and the Bohr effect to assess stored red blood cell quality.

## Key findings

- The Bohr effect significantly influences oxygen supply efficiency and varies with environmental oxygen affinity.
- Theoretical oxygen-release capacities differ notably between plateau and plain environments.
- Stored rat red blood cells showed consistent trends in P50, Hill coefficient, and acid-base sensitivity index.

## Abstract

Hemolysis rate is usually used as the acceptance criterion for stored red blood cells (RBCs) in clinical practice. However, there is a current lack of parameters for the characterization of hemoglobin quality. This study aimed to incorporate oxygen affinity, cooperativity, and the Bohr effect into a parameter system to monitor oxygen supply efficiency in stored RBCs, potentially serving as a basis for quality assessment. Han Chinese blood from plains, Tibetan blood from plateau, bovine hemoglobin (bHb), and a dextran–bovine hemoglobin conjugate (Dex20-bHb) were analyzed using the BLOODOX-2018. Oxygen affinity (P50) was determined by oxygen dissociation curves (ODCs) at pH = 7.4. Cooperativity was assessed through the Hill coefficient, calculated from the fitting range of the Hill equation. The Bohr effect was evaluated by the acid-base sensitivity index (SI) under simulated pH conditions of the lungs (pH = 7.6) and tissues (pH = 7.2) to calculate corresponding P50 values. Oxygen partial pressures (PO2) simulating lungs (PO2 = 100 mmHg for plains and 60 mmHg for plateau) and tissues (PO2 = 40 mmHg for plains and 30 mmHg for plateau) were used to calculate theoretical oxygen-release capacities in both environments. Multiple regression analysis explored relationships among parameters, constructing a system to assess changes in rat RBCs during storage. Optimized test methods determined P50, Hill coefficient, SI, and theoretical oxygen-release capacities for Han Chinese blood, Tibetan blood, bHb, and Dex20-bHb samples in various environments. We constructed a parameter system to characterize blood’s oxygen supply efficiency, revealing the significant influence of the Bohr effect. This influence varied with environmental changes in oxygen affinity. We validated the system using stored rat RBCs, finding consistent P50 trends with predictions, and initial increases in Hill coefficient and SI followed by decreases. Theoretical oxygen-release capacities varied significantly between plateau and plain environments. These results support using oxygen supply efficiency to assess RBC storage quality for developing transfusion strategies. P50, Hill coefficient, SI, and theoretical oxygen-release capacity in different environments can be incorporated into blood oxygen supply efficiency characterization systems to assess the quality changes in RBCs during storage.