A report by medical researchers at the Cleveland Clinic could have far-reaching implications for the nation's blood transfusion practices. It found that the longer blood is stored - typically up to six weeks - the more likely there are to be adverse effects on patients, especially those undergoing heart surgery.
While there have been other studies suggesting potential dangers using blood stored for more than two weeks, the Cleveland researchers say theirs is the largest.
For that reason, it bears close scrutiny and should be part of the ongoing medical debate about the safety of the country's blood supply.
The report, published in the New England Journal of Medicine, concluded that the storage time of donated blood may be more critical than previously believed. Clinic scientists found that cardiac-surgery patients who received blood that was more than two weeks old appeared to be at greater risk for infection, kidney failure, and even death than patients transfused with fresher blood.
The researchers focused on patients undergoing heart surgery because they consume a substantial share of the nation's blood supply. The Cleveland team tracked 6,002 patients who underwent bypass or valve replacement surgery and found the death rate in the hospital after the surgery was 2.8 percent for the group that got older blood compared with 1.7 percent for those getting fresher blood.
Scientists have known for a while that the longer blood sits unused, the more it degrades. Blood banks typically distribute the oldest blood first to keep from having to throw any of it out. With more than 14 million units of blood given to patients in the U.S. each year, shortage is a chronic problem.It's why the Food and Drug Administration, which establishes the nation's blood-use policy, isn't in a big hurry to change any regulations pending "more definitive scientific information." The same goes for the American Red Cross.
But Dr. Colleen Koch, a Cleveland Clinic cardiac-surgery anesthesiologist and the study's lead author, believes "blood banks need to explore changing their inventory-management practices." Beyond boosting the stockpile of donated blood, another option might include distributing newer blood first to those who would benefit most.
At the very least, says the researcher, the study findings should prompt doctors to be even "more conservative with how they approach blood transfusion."
Until scientists know why older stored blood may be bad for some patients, efforts must continue to minimize the need for transfusions during surgery.
Patient survival may depend on it.
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