Should oxygen-delivery potency matter more than hemoglobin concentration alone?
Hemoglobin concentration tells us how much hemoglobin is present. It does not, by itself, quantify how effectively a specific blood product or hemoglobin formulation loads oxygen, unloads it under tissue conditions, interacts with flow and microcirculation, or ultimately contributes to tissue oxygen delivery.
01 / What changed in 2026
A functional potency question can now be asked quantitatively.
Rogers and colleagues introduced lung-to-tissue oxygen flux, L-TOF, as an in vitro metric for comparing oxygen-delivery potency across fresh and stored red-cell products and formulations containing hemoglobin-based oxygen carriers.
The authors explicitly note that transfusion dosing is commonly based on hemoglobin levels without accounting for differences in oxygen-delivery potential between products.
02 / BHOC research hypothesis
Concentration should not be confused with function.
For BHOC development, the central question is not simply how many grams of hemoglobin are administered. The more useful development question is how much reproducible oxygen-delivery function a defined dose provides under relevant physiological conditions.
A functional potency framework could eventually connect formulation attributes, oxygen affinity, dose and oxygen unloading with downstream physiological endpoints. That relationship has to be demonstrated, not assumed.
03 / The evidence signal
L-TOF suggests that equal volume or equal hemoglobin does not automatically mean equal modeled oxygen-delivery potency.
300 mLFresh RBC reference dose in the study's in vitro comparison.
476 ± 21.6 mLDay-42 stored RBC concentrate modeled as equipotent to 300 mL fresh RBCs.
158%Modeled dose increase reported for day-42 stored RBC concentrate in that comparison.
From analytical potency to clinically meaningful oxygen delivery.
Which potency metric?Which in vitro oxygen-loading and unloading measurements are robust enough for formulation comparison and release testing?
Which in vivo correlate?Which microcirculatory, perfusion or tissue-oxygenation measurements track with analytical oxygen-delivery potency?
Which clinical endpoint?Does a functional potency metric predict physiological recovery, organ injury, transfusion requirement or other clinically meaningful outcomes?
Evidence boundary: L-TOF is an in vitro predictive potency metric. It does not establish clinical superiority of BHOC, HBOCs or any blood product. Product-specific vascular response, nitric oxide interaction, microcirculatory flow, safety and patient outcomes remain separate questions requiring experimental and clinical evidence.