Old donated blood a risk after surgery
People who get old, stale blood during surgery are 30% more likely to die from complications afterwards than people who get fresh blood, a US study suggests.
The study reported today in the New England Journal of Medicine found blood older than two weeks seemed to be associated with more complications after heart surgery.
"We report that the relative risk of postoperative death is increased by 30% in patients given blood that has been stored for more than two weeks," the researchers say.
This can cause a dilemma, as many blood banks and hospitals cannot keep enough blood on hand that is so fresh.
The US 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, says study leader, Dr Colleen Gorman Koch, of the Cleveland Clinic Foundation.
Her team studied over 6000 patients who received heart surgery at the Cleveland Clinic. 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% among fresh blood recipients versus 2.8% for older blood. Rates for kidney failure, infection, respirator use and multi-organ 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.
Supply and demand
In a related commentary Dr John Adamson of the University of California at San Diego says it is not feasible to shorten storage time significantly without restricting the blood supply.
He also says there are important unanswered questions about whether the results would apply to transfusions recipients other than those in this study.
Adamson says the process of sending blood through a heart-lung machine may be causing damage to blood cells, reducing the shelf-life of the blood.
He also says older blood may be acceptable for other uses.
Koch says patients should be asking their surgeons if the hospital has a blood management program in place that reduces the need for having a transfusion in the first place.
"For cardiac surgery there are a lot of things you can do in the operating room to minimise the risk of receiving a blood transfusion at all," Koch says.
One method scavenges and recycles blood that would normally be lost in an operation.
And if surgery is being done on a non-emergency basis, doctors should first be treating any underlying anaemia a patient might have, Koch says. "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.
Australian authorities respond
The organisation responsible for collecting and processing blood supplies in Australia, the Australian Red Cross Blood Service (ARCBS), acknowledges the new study but says the age of transfused blood is beyond its control.
"Our national inventory data shows that the vast majority of blood components are issued by ARCBS within 14 days of collection," it says in a statement.
"Once blood has been issued, ARCBS cannot confirm the point in its shelf-life when the blood will be transfused. This will depend on the inventory management practices of the health provider, as well as any specific requests made by the treating doctor."