Blood and Blood Components

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GOALS OF BLOOD TRANSFUSION
The goal of transfusion medicine is to provide the safest and
the most appropriate blood product for the patient to meet the
desired outcome.
The transfusion should:
i. Aid the patient to improve his/her condition.
ii. The transfusion should have more benefits than the
potential risks.
The major indications for the transfusion of blood or blood
products are to restore or maintain the following:
1. Blood volume
2. Oxygen carrying capacity of blood
3. Hemostasis and
4. Leucocytic function
A patient’s clinical condition is the most important factor to
consider when determining the transfusion needs of the patient.
Once it has been determined that transfusion is necessary, then
it becomes crucial to ascertain which blood product or products
will best serve the needs of the patient.
A variety of components are available. With component
therapy many patients can benefit from the blood drawn from
one donor.
The reasons for separation of blood components are as
follows:
• From whole blood various components can be prepared.
Whole blood storage conditions are not optimal for all
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Essentials of Blood Banking and Transfusion Medicine
functional components of blood. For example, after 24 hours
of storage at 1° to 6°C whole blood has a few viable platelets
and granulocytes. Stable coagulation factors are well
maintained during storage, but heat labile factors like factor
V and VIII decrease with time and may not be adequate to
correct specific deficiencies in patients. The separation of
various components allows storage of each component at
the temperature and storage conditions required for in vitro
survival.
• Component preparation allows transfusion of specific
portion of blood product that the patient requires.
• Transfusion of required components avoids use of
unnecessary whole blood transfusion which could be contra-
indicated in some conditions. For example, risk of hyper-
volemia in an elderly anaemic patient with congestive
cardiac failure may not tolerate the transfusion of two units
of whole blood.
• Also whole blood exposes to unnecessary antibodies. It also
has white blood cells and platelets which can carry HLA
antigens and can stimulate the patient’s immune system.
PRINCIPLES OF COMPONENT PREPARATION
Component preparation programs must incorporate the
principles of aseptic techniques using sterile, pyrogen-free
equipment and solutions. Blood bags used for phlebotomy have
integral, sterile extra bags known as satellite bags attached to
the main collection bag. Approximately 450 mL of blood with
63 mL of anticoagulant is collected. Selected components can
be transferred into the satellite bags through a closed system
of tubing. The original phlebotomy bag may have one, two or
three satellite bags attached. In the preparation of all compo-
nents, sterility has to be assured. A break in the seal of a product
at 20° to 24°C requires to be used within 4 hours.
Component preparation and separation is based on the
principle that different components of whole blood have
different specific gravities. For example, red cells represent the
heaviest portion of whole blood with a specific gravity of 1.08
to 1.09, whereas platelets range between 1.03 and 1.04. Using

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differential centrifugation with light spin of donated blood, the
components separate into layers in the blood bag. The heaviest
component settles to the bottom. In a unit of whole blood, the
centrifuged products settle out in the following layers, starting
from the bottom of the layer: Red blood cells, white blood cells
and platelet-rich plasma (PRP). After separating the red cells
from PRP, the plasma is centrifuged again for a longer time
and at a harder (heavy) spin. This time the platelets settle at
the bottom of the bag. The plasma is drawn off into the sterile
connected bag with the platelets remaining in the first bag.
It is possible to make components with closed system or open
system. Components prepared open system carry an increased
risk of bacterial contamination.
Components containing red cells are the following:
• Unmodified stored whole blood
• Fresh blood

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Essentials of Blood Banking and Transfusion Medicine
• Packed red blood cells (concentrated red cell suspension/PRBC)
• Optimal additive red cell suspensions
• Leucocyte poor/depleted red cells
• Deglycerolized red blood cells
• Rejuvenated red cells
Unmodified Stored Whole Blood
The approximate volume of each pack is 400–500 mL (450 with
63 mL of anticoagulant or 300 with 49 mL anticoagulant). Stored
whole blood provides both plasma proteins and red cells. With
storage there is decline in oxygen carrying capacity, but this
reaches normal levels within 24–48 hours following transfusion.
Labile factors, principally factor V and factor VIII, will also
be reduced. Functional platelets and granulocytes are absent
but their antigenic residues are present.
Stored whole blood was often used in earlier days. With
increased demand for blood components have now reduced
its use.
Indications whole blood
• Massive blood transfusion
• Exchange transfusion
Fresh Blood
Fresh blood that is collected within the preceding 24 hours
provides volume, red blood cells with normal oxygen affinity,
coagulation factors and platelets. Potassium levels are in normal
levels, whereas they are elevated in stored blood. In conditions
where platelets are of paramount importance, blood has to be
transfused soon after collection and certainly prior to refrigera-
tion.
Special requests for fresh blood may be received on occasion
for selected patients such as neonatal patient. Newborns are
sometimes candidates for fresh blood because newborn has a
high percentage of fetal haemoglobin which does not release
oxygen to the tissues.
The levels of 2,3-diphosphoglycerate may be decreased in
certain conditions such as respiratory distress syndrome. Using

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the same rationale, an exchange transfusion is another
procedure in which it is appropriate to use blood of less than
seven days old.
Red Cells Suspensions (Packed Red Blood Cells)
Packed red cells are prepared by removing most of the plasma
from a unit of whole blood. Since red cells have a higher specific
gravity than plasma, they move to lower portion of the
collection bag by either gravitational settling or centrifugation.
Then this plasma portion is removed from top of the bag into
a satellite bag. This plasma portion may be used for further
component preparation.
These red cells packs are named with anticoagulant or
preservative used in the primary bags. For example, if anti-
coagulant CPDA-1 is used, the red blood cell product is labeled
as CPDA-1 red blood cells. All anticoagulants and preservatives
solution used for whole blood are approved for red cells except
heparin. Heparin is used for whole blood only. Red blood cells
have an approximate volume of 300 mL. The final haematocrit
of packed cells should not exceed 80% (range 0.65–0.75) and
should be stored at temperature of 1° to 6°C.
Red cells packs are used for:
• Patients with symptomatic anaemia because they provide
needed oxygen carrying capacity without unnecessary
volume.
• Red cells may also be used for newborn exchange trans-
fusion. In these patients the unit should be less than 7 days
old to avoid problem associated with increased potassium
levels in the neonate and to ensure maximum 2, 3-DPG levels.
• Red cells packs can be used in surgeries.
Optimal Additive Red Cells Suspensions
These are red cells packs to which around 100 mL of a nutrient
preservative solution have been added. They are used under the
same circumstances as red cells. The lower haematocrit permits
faster infusion flow rate. For details refer to topic on “preservation
of blood, principles and its applications in blood banking”.

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Essentials of Blood Banking and Transfusion Medicine
Leucocyte-depleted (Reduced) Red Cells
Leucocytes in blood products can induce adverse reaction in
sensitized patient. These side effects include non-haemolytic
febrile transfusion reaction (NHFTR) which is caused by allo-
immunisation of the patient to foreign human leucocyte
antigens (HLA).
Leucocyte deduction can effectively reduce the incidence of
these adverse reactions and can also reduce the risk of trans-
mission of certain viral infection that are primarily found in
leucocytes, e.g. CMV, EBV and HTLV-1.
Leucocyte reduced red cells can be used:
• Prophylactically to reduce the risk of allo-immunisation to
HLA antigens in transplant patients.
• In patients with long-term multi-transfusion therapy to
avoid non-haemolytic febrile reactions.
Methods of preparation of leucocyte reduced red cell products
include the following:
• Centrifugation
• Saline washing
• Spin-cool-filtration
• Freezing and deglycerolization
• Bedside filtration
• Pre-storage filtration
In the centrifugation method of leucocyte reduction, the
buffy coat layer between the red cells and plasma is drawn off
into a satellite bag, along with some of the red cells. The same
procedure can be followed in inverted position. The red cells
are drained into satellite bag, leaving the leucocyte and plasma
in the primary bag. Although this is a simple and cost effective
technique, when compared with other techniques the leucocyte
reduction is only 70–80% of the original number. Up to 20% of
the red cells are lost by this procedure.
Washing of red cells removes leucocytes and plasma. This
removes 70–95% of leucocytes and 14–15% of red cells. The
washed cells have an expiration time of 24 hours. This method
of leucocyte reduction is comparatively expensive owing to
the washing equipment and special bags required.

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The spin-cool-filter method removes approximately 90%
leucocytes. Less than 10% of red cells are removed. The red cells
are centrifuged at 1° to 6°C in an inverted position, placed in
4°C storage for 3 hours and then filtered using a standard micro-
aggregate filter prior to infusion at the bedside. The centrifuga-
tion brings the white cells together in the buffy coat layer, the
cooling further aggregates the white cells and the micro-aggregate
filter removes the leucocyte aggregates. Although this procedure
is labour intensive, it is cost effective and simple.
Red cells can be frozen in glycerolized state and later thawed
and deglycerolized. The deglycerolized red cells have leucocyte
reduction in the range of 95–99% but have a red cell loss of
20%. To get deglycerolized red cells for leucocyte reduction is
an expensive procedure. Once the product is thawed, the shelf
life is only for 24 hours.
Leucocyte reduction can be achieved with use of leucocyte
depletion filters at the patient’s bedside. Leucocyte reduction
filters are used during infusion in place of standard blood filter.
Leucocyte reduction filters reduce leucocytes in the product
by 99% and allow greater than 90% of the red blood cells to be
transfused.
Pre-storage filtration for leucocyte reduction: Leucocytes
begin to disintegrate quickly when stored at 1° to 6°C. These
white cell fragments may be capable of initiating an immune
response to HLA antigens and also can release cytokines and
chemical mediators like histamine and causes FNHTR. In order
to prevent the fragmentation of leucocytes, it may be desirable
to remove white cells before storage using a sterile connection
device or in-line filter. The donor’s red cells are filtered within
8 hours of phlebotomy.
Deglycerolized/Frozen Red Blood Cells
Red cells are frozen in glycerolized state and thawed and de-
glycerolized. Frozen red cells are prepared for various reasons
which may include: (1) Storage of blood from a rare donor and
(2) Autologous units for future scheduled surgery.
The red cells from a whole blood are separated and frozen
within 6 days of donation. Freezing allows extended storage
up to 10 years from the date of original phlebotomy.

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Essentials of Blood Banking and Transfusion Medicine
Freezing of red cells requires the addition of cryoprotective
agent prior to freezing to prevent cellular damage or haemo-
lysis. To provide maximum protection, an optimal balance
between cellular dehydration and intracellular ice crystal
formation must be achieved. The basic methods for cryo-
precipitate are: (1) High glycerol, (2) low glycerol and (3) agglo-
meration. High glycerol is used by most of the organizations.
In this method, the red cells are prepared for cryopreservation
by the addition of 6.2 M glycerol to the red cells. The final
concentration of glycerol is 40% weight of solute per volume
solution (w/v), with approximately 400 mL of 6.2 M glycerol
added to the red cells. The process is done in two steps allowing
gradual equilibration of the glycerol in the red cells. For best
results red cells and glycerol are mixed at room temperature to
allow diffusion of glycerol into the cells. Then the red cells are
frozen at –80°C and stored at –65°C. For deglycerolization, the
cryoprotective glycerol must be slowly removed and replaced
with isotonic solution before transfusion to the patient. Frozen
red cells, once deglycerolized are stored at 1° to 6°C. Once the
product is thawed, the shelf life is only 24 hours from the time
the red cell bag was entered for deglycerolization.
Rejuvenated Red Cells
Red cells stored at 1° to 6°C, continuously loose both 2,3-DPG
and adenosine triphosphate (ATP). The level of 2,3-DPG
correlates with the ability of the red cells to deliver oxygen to
the tissues. The viability of the red cells correlates with ATP
levels. After transfusion, the levels of both 2, 3-DPG and ATP
return to normal in the patient within 24 hours of transfusion.
It is possible to restore the levels in vitro prior to transfusion
by the use of rejuvenation solution, e.g. REJUVENOL.
Ingredients of REJUVENOL in 50 mL of sterile pyrogen-free
water with pH 6.7 to 7.4 is given below:
Sodium pyruvate
550 mg
Inosine
34 mg
Dibasic sodium phosphate
500 mg
Monobasic sodium phosphate
200 mg

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The red cells are to be incubated with the rejuvenating solution
at 37°C for 1 hour. Only red cells can be rejuvenated. Once the
red cells are rejuvenated, they must be washed before transfusion
and used within 24 hours. Rejuvenation is an expensive process.
However, it is an excellent tool for preserving rare units of blood.
Platelet Preparations
Platelets are required for treatment of thrombocytopenic
patients, who are judged to be at risk of haemorrhagic symp-
toms.
Platelets are required in haematological malignancies,
particularly in acute myeloid leukemia. Platelets are valuable
in the treatment of acute self-limiting conditions or for isolated
bleeding episodes. In chronic states long-term blood transfusion
or platelet therapy is inevitable as it leads to allo-immunisation
against broad range of HLA or platelet-specific antigens. This
complication seriously diminishes the chances of providing
serologically compatible and clinically effective therapy.
The risk of bleeding is greater with falling counts than with
rising counts. Platelet counts below 10 × 109/L are at high risk
and patients who are not showing thrombocytopenic symptoms
may need prophylactic therapy. Patients with symptoms and
those requiring surgery with platelet counts ranging between
20–50 × 109/L platelets should be transfused.
Volume: 150–300 mL.
Unit of issue: SDP (1 therapeutic dose), has approximately
3.5–4 × 1011 platelets RDP (4–6 units—1 therapeutic dose), one
unit of RDP has average 5.5–7.5 × 1010 of platelets.
Infection risk: Same as whole blood.
RDP exposes to 4–6 donors and has chances of bacterial
infection.
Dosage: 1 unit of RDP/10 kg body wt. or 1 SDP.
Storage: 5 days at 22–24°C with agitation.
Not to be refrigerated.
Administration: Compatible donor required.
Precautions: Febrile transfusion reaction, allergic reactions.

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Acute transfusion reactions because of bacterial contamina-
tion.
Fresh Frozen Plasma and Related Products
One unit of plasma is obtained from centrifugation of one unit
of whole blood and usually contains 180–300 mL. When obtained
from single donor from plasmapheresis the amount of plasma
obtained is two to three times more than that obtained from
whole blood, i.e. 500 to 800 mL. When plasma is stored at
–20°C within 6 hours of collection is called fresh frozen plasma
(FFP). Cryo-poor or cryo-supernatant plasma is the plasma
product which remains after obtaining cryoprecipitate fraction
from FFP through cold precipitation.
Single donor plasma (source plasma) is stored at –20°C
within 6 hours of collection.
Plasma from whole blood obtained within 5 days of expira-
tion date of whole of blood is called recovered plasma.
Unit of issue: Usual pack of 200–300 mL.
Smaller volume packs for children.
Infection risk: Same as whole blood.
Storage: One year at –20°C.
Before use, thawed at 30–37°C, higher temperature will
destroy clotting factors and plasma proteins.
Precautions: Acute allergic reactions, especially with rapid
infusions anaphylactic reactions occasionally occur hypo-
volaemia alone is not an indication of use.
Dosage: Initial dose of 15 mL/kg.
FFP once collected from the blood bank can be preserved
at 1–6°C and has to be used within 6 hours.
Cryoprecipitate
One unit of cryoprecipitate is defined as that obtained from a
single FFP bag.
Procedure for preparation of cryoprecipitate: Thaw FFP at 1
to 6°C. Precipitate will be formed at the bottom of the sterile
bag. This precipitate portion is re-suspended in 5–10 mL of

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plasma and re-frozen within 1 hour and stored at –18°C. This
can be stored for 1 year.
Cryoprecipitate has:
• Factor VIII (80–100 U)
• von Willebrand’s factor (80 U of the original plasma
concentration)
• Fibrinogen (100–250 mg)
• Fibronectin (50–60 mg)
• Factor XIII (40–60 U of the original plasma concentration)
The half life of factor VIII is 8–12 hours, so transfusion of
factor VIII is repeated every 8–12 hours. Cryoprecipitate is
thawed to 37°C before transfusion and administered through
standard blood filter. No compatibility testing is needed. It
has to be used within 6 hours of thawing.
Unit of issue: Single donor pack/6 or more packs of single
donor units pooled.
Infection risk: Same as plasma.
Administration: If possible ABO compatible.
No compatibility testing required.