Transfusions with blood that is 29+ days old are twice as likely to lead to nosocomial infections-- including pneumonia, upper respiratory infections and sepsis-- as transfusions with newer blood, a new CHEST 2008 study found.
Researchers studied 422 ICU patients from July 2003-Sept. 2006. In addition to finding that older blood carried higher risk, they found that the more "old" blood a patient got, the greater the risk of infection.
Current standards allow blood to be stored for up to 42 days, and the oldest blood is usually used first, to avoid waste ("sort of like milk in a supermarket", quipped one reporter.)
Given that the U.S. isn't exactly flush with blood supplies, it's unclear how best to use this new information. Tightening standards could cause a shortage.
Study director David Gerber, DO, noted in a press conference that "there is a national tendency to transfuse liberally, " and said providers need to work towards using blood more cautiously.
For tips on tightening up on transfusions, see this article in October ACP Hospitalist.