Blood 'Shelf Life' Shorter than we Thought? Loses Capacity to deliver Oxygen after Three Weeks

A Johns Hopkins study confirmed that red blood cells stored longer than three weeks begin to lose the capacity to deliver oxygen-rich cells where they may be most needed.

According to a report published online in the journal Anesthesia & Analgesia, investigators note that red cells in blood stored over longer periods tended to gradually lose flexibility required to squeeze through the body's smallest capillaries to deliver oxygen to tissue.

"There's more and more information telling us that the shelf life of blood may not be six weeks, which is what the blood banks consider standard," says study leader Steven M. Frank, M.D., an associate professor of anesthesiology and critical care medicine at the Johns Hopkins University School of Medicine.

"If I were having surgery tomorrow, I'd want the freshest blood they could find."

As blood banks are often lacking fresh blood, shorter storage periods would result in diminished inventory. However, researchers believe the current practice of transfusing blood stored up to six weeks may need to be reconsidered.

In a previous study from the New England Journal of Medicine, cardiac surgery patients who received blood longer than three weeks were almost twice as likely to die as patients who got blood that had been stored for just 10 days.

This study enrolled 16 patients scheduled to have spinal fusion surgery-a type of operation that typically requires blood transfusions.

Six of the patients received five or more units of blood, while 10 needed three or fewer units. The researchers drew samples from every bag of blood used - 53 in total - and measured the flexibility of the red blood cells. What they found is that blood older than 3 weeks was more likely to have less flexible red blood cell membranes, a condition that may make it more difficult for blood to deliver oxygen, according to Frank.