A SHORT NOTE ON BLOOD TRANSFUSION

Definition

Blood transfusion is the procedure of introducing the blood of a donor, or pre-donated blood
by a recipient into the recipient’s bloodstream.

Indications for blood transfusion

The need for blood transfusion in patients with acute hemorrhage is based on
• The volume lost
• The rate of bleeding
• The hemodynamic status of the patient; hematocrit may be normal if determined.
• A patient with acute blood loss of more than 2000ml certainly requires replacement of
blood. It must be remembered that crystalloid infusions should be provided while the
blood compound is obtained.
For patients with chronic blood loss or chronic anemia replacement of blood (RBC) should
be based on the hematocrite level. The optimal hematocrite is considered to be in the range
of 30%. But patients with chronic anemia (e.g. renal failure) seem to tolerate hematocrite as
low as 18%-20%. Symptomatic patients exhibiting air hunger, dizziness, significant
tachycardia or cardiac failure should, of course, be transfused.
Component therapy is indicated when specific factor deficiencies are demonstrated. For
instance, factor VIII concentrates is the preferred mode of therapy for classic hemophilia.

Compatibility tests

If administrated blood is incompatible with the patients own blood, life threatening reactions
may result. Blood banks routinely test for incompatibilities of the ABO and RH systems.
Cross matches allow for detection of rare antibodies (e.g. kell, duffy, kidd) that are not

detected in ABO and RH tests. Group-A contains anti-B antibodies, Group-B contains anti-A
antibodies, Group-O contains anti-A and anti B antibodies. AB-group can receive any blood.
Blood prepared after a full typing and cross match can be transfused safely in 99.95%
cases. In some instances when fully cross- matched compatible blood is depleted or
unavailable; type specific or O negative blood should be given. Type O Rh negative blood
can be transfused without lysine the recipients blood.. Irregular recipient antibodies cannot
be detected and extra vascular hemolysis can also occur. Overall, O negative blood, if
randomly transfused, has a serologic safety of about 99.8%.

Component therapy

Treatment of specific hematologic abnormality often requires only a single component of
whole blood. For example, factor VIII for classic hemophilic or platelet transfusion for
patients with bone marrow suppression. Blood banks reduce the whole blood received from
donors to a variety of components. The available products include whole blood, red blood
cells, white blood cells, platelet concentrates and plasma in several forms.

Cellular component

Whole blood
This is collected in citrate phosphate dextrose- adenine solution (CPDA-) and contains 450
ml of whole blood and approximately 60ml of anticoagulant preservative. When it is used
within 24 hours it is considered fresh, whole blood and after this time it is referred to as
stored. Whole blood has a shelf life of 35 days. In acute massive hemorrhage transfusion
with one unit of whole blood raises the recipient’s hematocrite by 3%.

Packed RBC
These are the remains after the plasma has been separated from whole blood. One unit
raises the recipient’s hematocrite by 3%. Packed RBC may be warmed to a temperature not
exceeding 370 c before transfusion. The storage life of red blood cells is 35 days.

Platelet concentrate
Platelets are separated from one unit of blood and suspended in a small volume of the
original plasma. Depending on this technique, platelets may be stored for 3-7 days. One unit
of platelet concentrate contains about 5.5×1010 platelets and increases the platelet count by
5000/ml. For a patient with platelet count below 25,000/mm3, 6-8 units are usually given.
Platelet concentrate must be administered through a special platelet filter.

Plasma components

Fresh frozen plasma
This is anti-coagulated plasma separated from a person’s blood and frozen within 6 hours of
the time of collection. It may be stored up to 1 year. It contains all clotting factors and also
provides proteins for volume expansion.

Cryoprecipitate
This is a protein fraction removed from a unit of fresh frozen plasma that is thawed at 40c.
This white precipitate is then removed and frozen. It has a shelf life of about 1 year. It
contains factor VIII, fibrinogen and factor XIII. It is used for the treatment of:
classic hemophilia,
certain consumptive coagupathies such as DIC or
Other clotting abnormalities with specific therapy commonly not available.

Albumin
This is a plasma component used for oncotic support and plasma expansion. Its
disadvantages are rapid excretion as well as expense.

Plasma protein fraction
Similar to albumin but contains additional protein molecules.

Complications and risks of blood transfusion

Hemolytic transfusion reactions
Intravascular hemolytic transfusion reactions; are potentially life threatening reactions that
can occur by blood transfusion. They are almost always due to incompatibility of the ABO
system involving the donor red blood cells and recipient plasma. These reactions are very
rare occurring in 1 out of 15,000 -20,000 transfusions.

Pathophysiology
During hemolytic transfusion reaction all donor cells hemolyze, leading to hemoglobinemia,
hemoglobinuria and renal failure. These reactions also activate the complement system with
subsequent release of vasoacative amines causing hypotension. Complement activation
also initiates the clotting mechanism which can produce intravascular thrombosis, DIC and
hemorrhage

Clinical manifestation: Patient often experiences fever, chills and dyspnea.

Treatment
Stop transfusion immediately
Administration of fluids and diuresis with mannitol or frusemide
Transfused blood with patients blood sample should be sent for analysis
Sodium bicarbonate may prevent precipitation of hemoglobin in the renal tubules
Steroids may ameliorate the immunologic consequences.
Transfusion reactions from mismatches involving the Rh system or minor antibodies usually
induce extravascular hemolysis, since these reactions occur slowly, serious complications
do not often develop.

Non-hemolytic transfusion reaction
Non-hemolytic reaction may occur after transfusions.

Febrile reaction: occurs in 0.5% -1% of all transfusions and is usually treated with
antipyretic drugs.

Allergic reaction: occurs in 2-3% of all transfusion and manifests by urticaria and
rashes. Antihistamins, steroids or epinephrine as indicated can accomplish
treatment.

Transmission of disease: With the exception of albumin and PPF, the use of all
blood products carries risk of transmitting infectious diseases. These include:
• hepatitis
• malaria
• Epstein- bar virus, cytomegalovirus, brucellosis, trypansomiasis and
other diseases potentially transmitted by blood transfusions
Of great concern these days is the risk of transmission of the HIV virus. It is required
to screen the donated blood using enzyme- linked immunosorbent assay (ELISA).

Other complications: Complications that can occur with massive transfusion include
• Citrate toxicity
• Acidosis
• Hyperkalemia

N.B:- As blood transfusion is accompanied by various complications mentioned above, the
decision to transfuse should only be made when it is believed to be life saving.
Posted by Arun v j at 5/11/2014 12:27:00 pm 

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