Hi Chirley,
I always look at the blood units and they are between 4 and 14 days old. Since I have understood that the blood is best before it is 10 days old I have controlled if fresher blood functions better so I don't need a new transfusion so soon but found no difference. I have so much antibodies that they have difficulties to find blood for me - perhaps they have found that fresher blood is better for me.
Here is a report about fresh/old blood. They have at least two explanations about why fresher blood is better.
The first is that stored blood gradually loses its ability to get oxygen to tissues, largely through loss of a blood vessel dilator called nitric oxide.
The second is that some kind of microparticles play a role in blood clotting and inflammation, and that they start accumulating inside blood bags around day 10.
http://www.cbsnews.com/stories/2010/...n6714971.shtml
Kind regards
Birgitta-A