Microvascular perfusion upon exchange transfusion with stored red blood cells in normovolemic anemic conditions.

Animal experiments which seem to be very problematical because the animals seem to have a severe respiratory acidosis and the investigated skin is not the critical organ regarding oxygen consumption. Furthermore, collection of the blood (vacuum) being retransfused differed considerably from regular collection of blood units used for blood transfusion. No information is given regarding its characteristics. Stored RBCs reduced microvascular flow, decreased functional capillary density and oxygen extraction, which was not evidenced by the analysis of systemic parameters. The authors draw the surprising and rather speculative conclusion that increasing Hb levels with the transfusion of stored RBCs may be beneficial because it is a mechanism for targeted oxygen delivery, only releasing oxygen when tissue oxygen levels are low.

– Volker Kretschmer