Many blood transfusions may increase risks, doctors warn, the Guardian reports, apparently based on a story in New Scientist. Well, I agree completely, but then the piece goes on rambling about how boffins don't understand why blood that has been stored is often doing more harm than good.
In fact, last October, two independent and very convincing papers (one was actually commissioned to check the findings of the other, because of the enormous importance of the issue!) showed that there is a very simple reason, and a very simple way to fix the problem.
Fresh blood contains nitric oxide (NO) bound to hemoglobin, which it loses within hours of storage. NO is needed as a signal to widen the blood vessels. So old blood without NO will lack the vessel-dilating effect and thus the oxygen provision may be no better than or even worse than what the patients could achieve with their own blood. The problem is easy to fix, as NO can be added to the stored blood before transfusion, making it good as new.
I reported all that in Chemistry World and in this blog entry, back in October. Naively, I would have hoped that by now medics would have made moves to implement the fix, rather than scratching their heads over a question that has already been answered.