Blood stored longer may be less safe for patients with massive blood loss and shock

Human blood from donors can be stored for use up to 42 days, and it is a mainstay therapy in transfusion medicine. However, recent studies looking back at patient records have shown that transfusion with older, stored blood is associated with adverse effects.

For severely injured patients who have massive bleeding and receive many transfusion units, older blood was associated with dysfunction in blood flow, increased injury and inflammation in critical end organs, and lung infection.

In a collaborative study using a mouse model, University of Alabama at Birmingham researchers from the departments of Anaesthesiology and Perioperative Medicine, Biostatistics, Emergency Medicine, Pathology, and Surgery have found mechanistic links between older stored red blood cell transfusions and subsequent bacterial pneumonia.

This may reveal new approaches to improve safety of stored red blood cell transfusions.

The key player is free heme, a breakdown product from degraded red blood cells. Heme is part of the oxygen-binding haemoglobin pigment that gives blood cells their red colour and carries oxygen through the body from the lungs. While in the red blood cell, heme is relatively safe; but once outside the confines of the red cells, free heme is toxic and can cause tissue injury. During storage and upon transfusion, stored red blood cells lyse open, releasing free heme.

An adverse role for heme suggests that finding ways to limit heme exposure or prevent heme toxicity may improve safety of stored red blood cell transfusions, say UAB researchers Rakesh Patel, Ph.D., and Jean-Francois Pittet, M.D.

Patel is a professor of pathology and director of the Center for Free Radical Biology, and Pittet is a professor of anesthesiology and perioperative medicine at the UAB School of Medicine.

University of Alabama at Birmingham