Heart surgery patients are more likely to die or suffer problems if they received transfusions of blood that is more than two weeks old rather than fresher blood, according to a new study that adds to the debate about the shelf life of blood.Although not the final word, the study underscores concerns that blood deteriorates with age and that rules allowing blood to be stored for six weeks may pose a safety risk, at least for certain patients.The findings bolster the argument of those who believe that older blood should be avoided, wrote Dr John Adamson of the University of California at San Diego, in an editorial accompanying the study in New England Journal of Medicine.“However, the results of this study will not settle the debate” because the patients studied were not representative of all transfusion recipients, he added. The report was limited to heart surgery patients, but similar results have been shown in smaller studies that looked at other types of patients. The study’s lead author, Dr Colleen Gorman Koch of the Cleveland Clinic, said a more rigorous study is already underway.It’s not clear exactly why blood stored for longer periods is riskier. Some researchers say stored blood becomes depleted of oxygen-carrying chemicals. Red blood cells also become more rigid in storage, impeding their flow through the body.Researchers examined the records of 6,000 patients who were given blood transfusions during heart-bypass or heart-valve surgery. All the patients were treated at the Cleveland Clinic between 1998 and 2006.A little less than half of the patients received blood that had been stored for 14 days or less, and a little more than half got blood that was older. The amount of blood given to patients in both groups was similar. The study found that the one-year survival rate was 89 per cent for those who got older blood, but nearly 93 per cent for patients who got fresher blood.Complication rates were higher in the older blood group, with higher proportions of those patients suffering kidney failure, blood infections or multiple organ failure, or needing ventilator care more than 72 hours after surgery. The average age of the “old” blood was 20 days. The average age of the fresher blood was 11 days.The findings were similar to smaller studies of colorectal cancer surgery patients in Denmark, cancer surgery patients in Spain, sepsis patients in Canada and trauma patients in Colorado. Each of those studies found higher rates of various complications in patients who received older transfused blood when compared with patients who got fresher blood.
