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TUESDAY, March 5 (HealthDay News) -- A small new study adds more evidence that red blood cells stored longer than three weeks begin to lose their ability to deliver oxygen-rich cells to the tissue where they're most needed.
Researchers from Johns Hopkins University in Baltimore found that red cells in blood stored for that long gradually lose the flexibility needed to squeeze through the smallest capillaries. They also found that this ability does not return when the blood is removed from storage and transfused into patients during or after surgery.
The study included 16 patients scheduled for spinal-fusion surgery, which typically requires blood transfusions. The average age of the blood given to the patients was more than three weeks.
The findings were published online Feb. 28 in the journal Anesthesia & Analgesia.
"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," study leader Dr. Steven Frank, an associate professor of anesthesiology and critical care medicine at the Johns Hopkins University School of Medicine, said in a university news release.
"If I were having surgery tomorrow, I'd want the freshest blood they could find," he added.
Frank said he realizes that blood banks do not have enough fresh blood for everyone, and that shorter storage periods would lead to lower blood inventories. He said, however, that the current practice of transfusing blood stored for up to six weeks may need to be reconsidered.
Frank noted that a previous study published in the New England Journal of Medicine found that heart-surgery patients who received blood stored longer than three weeks were nearly twice as likely to die as those who received blood stored for just 10 days.
Currently, two large studies are under way in the United States and Canada to compare the safety of older and newer blood. The results are expected next year.
The American Association for Clinical Chemistry has more about blood banking.