I've summarized the data in this letter:
https://www.bmj.com/content/366/bmj.l4968
In randomized trials, the fresher blood arm is associated with a higher incidence of nosocomial infection (immunomodulation, presumably). There has never been any data examining clinical outcomes that actually favors using very fresh blood. Mostly just "expert opinion" and "it seemed like a good idea." That's not good enough now, in my view.
Two key references (one only published in abstract form) are:
Alexander PE,
Barty R,
Fei Y,
et al
. Transfusion of fresher vs older red blood cells in hospitalized patients: a systematic review and meta-analysis. Blood2016;127:400-10. doi:10.1182/blood-2015-09-670950 pmid:26626995
Abstract/FREE Full TextGoogle Scholar
↵
Schmidt A,
Gore E,
Cholette JM,
et al
. Oxidation reduction potential (ORP) is predictive of complications following cardiac surgery in pediatric patients[abstract]. Transfusion2016;56(Supplement S4):20A-1A.
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