This article confirms previous findings that using high-affinity haemoglobin oxygen carriers including modified RBCs, haemoglobin vesicles and PEG-conjugated haemoglobin provides improved oxygenation of ischaemic tissue relative to using low-flow-affinity carriers. Mechanistically, this is due to the significant longitudinal oxygen gradients present along the vasculature in organs and tissues, which cause low-affinity haemoglobin to release oxygen much before the oxygen carrier arrives to the critically ischaemic region. This process was extensively investigated by Sakai et al. (Am J Physiol Heart Circ Physiol 2005;288:H2897-903) and Cabrales et al. (Am J Respir Cell Mol Biol 2008;38:354-61).

– Marcos Intaglietta