FEATURE
One reason for lingering concern is
that the trialists set their own limits for
what constitutes “fresh” and “old” RBC
units – and there may never be a universal
definition, Dr. Hébert said.
“The definition of ‘fresh’ is different at
different institutions,” he explained. “[In
ABLE] we were pragmatic and set a limit
”The answer to
the question of
whether there is
a difference between fresh and
old blood seems
to be an unequivocal ‘yes.’ ... But
does it matter?”
—JASON ZIMRING, MD, PhD
of seven days for fresh blood, since it takes
two days to get the blood into the hospital
in the first place. For us, a week was fresh
enough.” Though, he adds, setting a universal definition was not the goal of the trial.
“What we really wanted to do was understand the clinical impact and outcomes.”
What about focusing on the other end
of the spectrum of blood freshness – deciding how old is too old? In other words,
is there a point beyond which stored
blood becomes ineffective or even harmful? The jury is still out on whether using
blood at the extreme end of the storage
cycle (up to or at 42 days) would have
detrimental outcomes for transfusions,
and it may be a while until the medical
community gets those answers.
Running a trial that tests old versus older
or oldest blood would be problematic, Dr.
Hébert said. “For me, old blood is over 30
days, but we still don’t know at what point
blood gets ‘very old’ and potentially dangerous. To push the limit of that question
in pa F