Old blood link to heart deaths30th June 2006
American researchers say increased risks of premature death following repeat heart surgery could be linked to the age of blood used in surgery.
In a study of patients undergoing repeat heart surgery, researchers found that the risk of premature death, both in the hospital and long-term, increased significantly with each day the transfused blood had been stored. The US Food and Drug Administration regulations allow the refrigerated storage of liquid blood for 42 days.
Red blood cells, the authors write, undergo significant changes during storage, including an increase in abnormally shaped red blood cells that may impair oxygen delivery to tissues.
In a retrospective study of 321 heart surgery patients, the scientists found that the rate of in-hospital death increased by 8.5 percent and out-of-hospital death by 10 percent for each additional day the transfused blood had been on the shelf.
Dr. Elliott Bennett-Guerrero, the lead author on the study and an associate professor of anesthesiology at Duke University, said the question of aging blood has been around for decades.
Rates of in-hospital mortality ranged from about four per cent among patients who received the "newest" blood (1 to 19 days old) to 25 percent among those who received blood that had been stored for 31 to 42 days.
Although the retrospective nature of the study, which appears in the July issue of the journal Anesthesia & Analgesia, prevented the scientists from determining the exact mechanism at work, they were able to track kidney failure as one effect.
Transfusions with older blood were a significant predictor of post-operative kidney function and the length of hospital stay also went up consistently with the age of the blood used.
The average age of most transfused blood, Dr. Bennett-Guerrero said, is about two to three weeks.
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Title: Old blood link to heart deaths
Author: Chris May
Article Id: 445
Date Added: 30th Jun 2006