Beware of Aging Blood ( By TIME - Jun. 22. 2006 )

In a study of surgical heart patients, researchers at Columbia University and Duke University Medical Center report that patients fared significantly worse after receiving transfusions of blood that had been stored a long time. Compared with patients who were transfused with fresher units of blood, those given blood that had been banked for 31 to 42 days (after 42 days, national blood banks discard unused donations) spent twice as much time in intensive care and had a higher risk of kidney problems and death.

Working under the assumption that the impact of blood-storage duration would be most significant in patients receiving multiple transfusions, researchers studied the medical files of 321 high-risk repeat surgery patients, all of whom underwent open-heart operations for coronary artery bypass or valve replacement and received five units of stored blood on average.

The study, published in the journal Anesthesia & Analgesia, found that as the age of transfused blood went up, so did the risk of patients’ post-surgical problems and death. The in-hospital mortality rate for patients given blood that had been banked fewer than 20 days was about 4%; for patients transfused with the oldest blood, stored 31 to 42 days, that rate rose to 25%. In the latter group, patients spent an average 7 days in intensive care and had a 45% chance of suffering kidney damage. Meanwhile, patients transfused with the youngest blood, spent 3.5 days in the I.C.U. and had a 7% risk of kidney problems. Within the eight years following surgery, 16% of the heart patients died, and researchers found that the average age of the blood they received as well as the oldest unit they received were both predictors of later death.

What It Means: The current study linked blood-storage duration with the risk of complications after surgery, but it didn't explore why one might cause the other. Past studies suggest possible reasons: stored blood progressively loses oxygen-carrying efficiency and red blood cells may become more rigid over time, perhaps hindering their ability to circulate properly.

One limitation of the current study, however, is that patients who received the oldest blood were also more likely to have received the most transfusions overall, which may have contributed to their poor outcomes. To better understand how length of blood storage affects patients’ health, the study’s authors call for a larger, randomized trial.

From the Archives
May 29, 2006 Outsourcing Your Heart
October 18, 2004 Bad Blood


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