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Are patients who get "older" blood at greater risk for complications?
It's a question with big implications for the nation's blood supply that is already short. Many hospitals around the country are starting new studies to determine if "fresher" blood really is better for some patients. The FDA allows red blood cells to be stored for 42 days, and hospitals must use the oldest blood first to ensure none expires. Scientists have long known that stored blood breaks down the longer it's stored. Recently a number of small studies suggested that blood well under the FDA's 42-day storage limit may increase the risk of complications like blood clots, infections, or organ dysfunction.
Dr. Colleen Koch at the Cleveland Clinic (Ohio) examined records of 6,000 past heart surgery patients. She found that those who received blood that was more than two weeks old were slightly more likely to die, required a ventilator longer, and had higher rates of infection and kidney failure than those who got fresher blood. Researchers in Connecticut reported similar findings in a study of 200 trauma patients. Could that really be true? Maybe those who got the oldest blood were just sicker patients.
To add to the controversy, other similarly studies concluded age of blood doesn't matter, finding no differences between patients who got older or fresher transfusions. So new research studies will attempt to answer the question. In one study, backed by the NIH, 15 hospitals will analyze the operations of 1,800 heart surgery patients, each of which will randomly be assigned blood that is over 20 days or under 11 days old. Similar studies are starting in Canada and at the Cleveland Clinic. The NIH is funding eight other studies to determine just what happens to stored blood that might trigger side effects. One leading theory is that stored blood gradually loses its ability to get oxygen to tissues, largely through loss of 2,3, DPG and a blood vessel dilator called nitric oxide.
Despite the controversy, many hospitals, including North Shore Medical Center, work to be more conservative with blood and actively seek to avoid transfusions whenever possible.