Blood stored for 29 days or more, nearly 2 weeks less than the current standard for blood storage, is associated with a higher infection rate in patients who received transfusions with the blood.
In a new study presented at CHEST 2008, the 74th annual international scientific assembly of the American College of Chest Physicians (ACCP), researchers found that patients who received transfusions with blood stored for 29 days or more were twice as likely to suffer from nosocomial infections, including pneumonia, upper respiratory infections, and sepsis, with the oldest blood being associated with the most infections. Currently, federal regulations allow red blood cells to be stored up to 42 days, after which they must be discarded.
"Stored red blood cells undergo changes that promote the release of a number of biochemical substances called cytokines, which can depress the recipients' immune function and leave them more susceptible to infection," said study author Raquel Nahra, MD, who conducted her research while at Cooper University Hospital, Camden, NJ. "Those changes start around 14 days of storage and reach a maximum after the blood is discarded at 42 days."
Researchers from Cooper University Hospital examined the association between the age of packed red blood cells and the development of nosocomial infections (NOSO) in 422 patients receiving blood transfusions who were admitted to an ICU from July 2003 to September 2006. Researchers performed an analysis of the age of the first unit of blood, age of the "oldest" unit of blood (OL), the average age of the unit of blood, and the outcome of NOSO.
"Previous data indicate that the average age of transfused blood is around 17 days old," said Dr. Nahra. "In our study, the average age of blood was 26 days, and 70 percent of all the blood transfused was older than 21 days, suggesting that a large pool of available blood is old blood with higher levels of cytokines and more potential for an immunosuppressive effect."