New Blood Rules by Joseph Benedetto Jr. , and Chris Van Deelen

     The human body holds a volume of blood between 4.5 and 6
litres (5 and 6 quarts, or 10 and 12 pints).  Let's say, for game
terms, that the human body has 5 quarts (5 litres) [10 pints] of
blood in it--a simple number for quick game mechanics.
     Now--take the total BP's of your favorite character and
divide them by that number, rounding up or down for simplicity. 
Using the NPC Bjorn Lindstrom from R-001, we have a character
with a BP of 320.  Divide that by 10 pints and you get a Bp/pint
value of 32.  (You could do this in metrics, using litres, and
get a BP/Litre value of 64.  Doesn't matter.)
     NOTE: this is a rough approximation only--for simple game
mechanics.  Also note that the value is going to be a bit
different for most people.  Using the next NPC from R-001, David
Guinn (BP 269) we divide his BP by 10 (pints) and get a BP/pint
value of 26.9, or (in round terms) 27.  Guinn's 27 is a good bit
different from Lindstroms's 32!
     Now--Tom Medic transfuses a pint of blood from Guinn to
Lindstrom as they lay outside the burning ruins of the Imp base. 
The following things happen:
     Guinn loses a pint of blood (donation).  His Total BP drops
by one pint, according to HIS BP/pint value, which is 27.  We
lower his Total BP from 269 to 242.
     Lindstrom gets a pint of blood (transfusion).  His Total BP
increases by one pint, according to HIS BP/pint value, which is
32.  We raise his wounds-lowered Bp by 32 points--the value FOR
HIS BODY of a pint of blood.
     Yes, the values aren't the same.  But a pint of blood is a
pint of blood, it never changes!  The BP transfusion value is a
rough game way of saying what a pint of blood is worth TO THE
INDIVIDUAL WHO RECEIVES IT, not what it is worth in and of
itself.  Since each person's BP value is different, we *cannot*
assign a single value to a litre or pint of blood--it has to be a
representative value of what the blood is worth to the individual
who receives it.
     If you add this to the game, you'll need to add a space to
the Player Character worksheet, something like :  "Blood value
______BP per ______"
     Using the example of Lindstrom quoted above, you'd fill it
in like  "Blood value 32 per pint", or "Blood value 64 per litre"
depending on whether you were using metric or American values.  

And another point:

     It's doubtful anyone will believe that human blood could
survive in storage in a bolt hole or cache for ANY length of
time--just too perishable.  But you COULD store four pint bags of
normal saline solution with ringers lactate in the MP Surgical
kit and expect it to come through storage all right (just like we
expect the rations, etc. to last for 150 years in inviolate
storage).
     The thing about blood and saline is that when a wounded man
is losing blood, he doesn't cry out for blood--he cries out for
water, since his body is dehydrating.  The quickest way to
counter blood loss is by administering intravenous fluid
replacement--a saline solution.  A critically injured man needs
VOLUME replaced, and it is not that important if the volume comes
from real blood or saline solution, so long as the victim's blood
volume is raised to counter Shock. His own bone marrow will start
filling that fluid with red blood cells on it's own.
     Of course, whole blood is better, but sometimes you don't
have it handy.  So you have to make do with saline solution from
the Surgical kit or the Drug kit (also, Saline doe NOT need to be
cross-matched as to blood type, which makes it handy in an
emergency!).  I suspect that in the later years of the Project
that "human blood substitutes" (the kind used on Jehovah's
Witnesses) would be obtained by the Project and added to the
medical kit as well.
     In game terms, these substitutes act to save the victim by
replacing lost volume in the bloodstream.  Given their efficiency
compared to whole blood, I think that the value of saline
compared to blood would be about 80%.  Thus, using the example of
Lindstrom quoted before--

Total BP: 320
BP/pint value: 32 (whole blood)
BP/pint value: 26 (saline solution)

[80% of 32 equals 25.6, which rounds to 26 points.]

Thus, if Lindstrom got a pint of whole blood, he'd get back 32
BP.  But if instead he got a pint of saline solution, he'd get
back 26 BP.
Ongoing blood loss and unconsciousness from blood loss should be
handled by using the WOUND SHOCK table already in the game book
(pg. 40-41), or you can use the following rules.
When the PC has lost two pints (1 litre): a -5% to all skill
rolls and both strength and dexterity are reduced by 1.
At three pints blood loss, all skill rolls would be at a -15%,
and both dexterity and strength will be at -3.
At four pints blood loss, all skill rolls would be at a -30%, and
both dexterity and strength will be at -6.
Anything beyond this amount most likely drops the character in
his tracks, although to be realistic it's probable that the
character is already unconscious from shock (using the WOUND
SHOCK table from the game book).  I would say that any character
suffering from blood loss AND trying to stay up and functional
would have to roll against "Wound Shock" and unconsciousness once
every Game Turn (10 minutes) not to pass out. This is, of course,
a combination of realism and playability.