Older Blood Riskier in Heart Surgery Transfusions

Blood used in transfusions closer to the 42-day maximum may be less healthy than fresher blood, according to a new study.

Researchers from Duke University Medical Center (Durham, NC, USA) took a retrospective look at the medical files of 321 patients who underwent repeat, open-heart surgeries for either coronary artery bypass or valve replacement between 1995 and 2001. The patients received a relatively large amount of donated blood--an average of five units--during these procedures. The researchers tracked the patients' incidence of in-hospital and long-term mortality, as well as post-surgical complications such as kidney failure. They compared the rate of those types of outcomes with the number of units and age of the blood each patient received.

In-hospital death rates rose along with the age of blood received. Specifically, repeat bypass patients who received the freshest blood during their operation (stored for one to 19 days) had a 4% in-hospital death rate, compared to a 25% rate in similar patients receiving the oldest blood (stored for 31 to 42 days). Another finding was the rise in hospital length-of-stay: an average of 3.5 days for those receiving freshest blood in comparison to seven days for those getting older units. Patients who received older blood also had higher rates of death in the eight years after their surgery, the researchers noted. The study was published in the July 2006 issue of Analgesia & Anesthesia

"One of the theories is that as red blood cells age during storage, they become stiffer,” said lead investigator Dr. Elliot Bennett-Guerrero, director of perioperative clinical research at Duke University. "There's lots of evidence that these stiffer red blood cells may not deliver oxygen as efficiently. Or, they may even clot up or get stuck in organs and cause those organs to become damaged.”

U.S. Food and Drug Administration (FDA) regulations prohibit the use of blood stored for more than 42 days.



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