Defining and quantifying oxygen delivery potency of blood products

Area of Science:

• Biomedical Engineering
• Hematology
• Physiology

Background:

• Transfusion therapy aims to restore oxygen (O2) carrying capacity, typically guided by hemoglobin (Hb) levels.
• Current transfusion practices do not account for the varying O2 delivery potential of different red blood cell (RBC) products or blood substitutes.
• A standardized metric is needed to assess and compare the O2 delivery potency of various Hb-based oxygen carriers.

Purpose of the Study:

• To develop and validate an in vitro metric for quantifying O2 delivery potency across diverse Hb formulations.
• To establish a method for comparing the efficacy of stored RBCs, whole blood, and artificial blood substitutes.
• To introduce a predictive tool for assessing transfusion quality and optimizing dosing.

Main Methods:

• Modeled O2 uptake and delivery across physiological gradients using matched O2 association and dissociation curves.
• Integrated data to compute a novel metric: lung-to-tissue O2 flux (L-TOF).
• Applied L-TOF to assess stored RBCs (sRBCc) and evaluate transfusion effectiveness in a massive transfusion model using crystalloid, stored whole blood (sWB), and artificial blood substitutes (WBAs).

Main Results:

• Quantified the O2 delivery potency of sRBCc, revealing a 158% dose increase needed for equipotency compared to fresh RBCs.
• Demonstrated that equipotent transfusion of day 42 sRBCc requires a significantly larger volume than fresh RBCs.
• Showcased L-TOF's utility in comparing transfusion effectiveness of crystalloid, sWB, and WBAs in a simulated massive transfusion scenario.

Conclusions:

• Lung-to-tissue O2 flux (L-TOF) provides a novel, quantitative measure of O2 delivery potency for blood products and substitutes.
• L-TOF enables direct comparison of O2 delivery potential, facilitating more accurate transfusion dosing and product selection.
• This metric offers a predictive readout of transfusion quality, potentially improving clinical outcomes in anemia and massive transfusion protocols.