People who got old, stale blood during surgery were 30 percent more likely to die than people who got fresh blood, U.S. researchers reported on Wednesday.
Two weeks seemed the be the cutoff, with older blood causing more complications, the researchers reported in the New England Journal of Medicine.
“We report that the relative risk of postoperative death is increased by 30 percent in patients given blood that has been stored for more than two weeks,” the researchers wrote.
This can cause a dilemma, as many blood banks and hospitals cannot keep enough blood on hand that is so fresh.
The U.S. Food and Drug Administration allows blood to be held for as long as six weeks, and blood banks typically give out the oldest blood first.
One solution may be to use the freshest blood first. Another is to use techniques to reduce the need for a transfusion in the first place, said Dr. Colleen Gorman Koch of the Cleveland Clinic Foundation, who led the study.
Her team studied 6,002 patients who received heart surgery at the Cleveland Clinic Foundation. Koch and her colleagues compared the outcome with the storage time of the blood transfused in each operation.
The rate of death while in the hospital was 1.7 percent among fresh blood recipients versus 2.8 for older blood. Rates for kidney failure, infection, respirator use and multiorgan failure were also higher if older blood was used.
However, a system that uses blood no older than two weeks would make it harder to keep blood banks properly stocked, and much more blood would be discarded. There are times when the blood supply falls to critically low levels, even with the current six-week limit.
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“It is just not feasible to shorten storage time significantly without restricting the blood supply,” Dr. John Adamson of the University of California at San Diego wrote in a commentary.
Adamson also said there are important unanswered questions about whether the results would apply to other medical procedures where transfusions are common. For example, the process of sending blood through a heart-lung machine may be causing damage to blood cells, reducing the shelf-life of each pint.
Older blood may be acceptable for other uses.
Koch said patients should be asking their surgeons if the hospital has a blood management program in place.
“For cardiac surgery there are a lot of things you can do in the operating room to minimize the risk of receiving a blood transfusion at all,” Koch said. One method scavenges and recycles blood that would normally be lost in an operation.
And if surgery is being done on a nonemergency basis, doctors should first be treating any underlying anemia a patient might have, Koch said. “So they’re getting themselves in tip-top shape prior to surgery to decrease their need for blood.”
In October, researchers reported that donated blood quickly loses nitric oxide in red blood cells — which is key to transferring oxygen in the blood to tissues.
But if nitric oxide is restored, banked blood appears to regain its power, the team at Duke University in North Carolina found.
Currently, about 5 million Americans receive blood transfusions each year, according to the National Institutes of Health.