BLOOD TRANSFUSION
Dr.Hadab Ahmed
1
Indications
• Blood is indicated for its:
1- Components:
R.B.Cs,platelets,coagulation factors&
plasma proteins.
2- Volume
Historically an Hb.<10 gm & Hct.< 30% was an
indication for blood transfusion.
With changing concepts, it is now difficult to define
the Hb.or Hct.at which blood transfusion is
indicated .This depends on clinical assessment,
taking these factors in consideration:
*C.V.S.
function.
* Age
*Anticipated loss
*Cardiac output & blood volume
Compatibility
testing
• These are : 1- Blood grouping.
2- Cross matching.
3- Antibody screening.
• These tests are done in vitro, so that
antigen-antibody reactions can be
prevented.
ABO-Rh Typing
• Most serious reactions are usually caused by accidental
transfusion of ABO incompatible blood.
• These reactions are due to naturally occurring antibodies
(anti A& anti B ) acting on RBCs antigens & leading to rapid
& serious intra vascular haemolysis.
• Antibodies in the plasma are directed against antigens that
are lacking in the individual's own cells
• Blood grouping is done by testing RBCs for A&B
antigens& serum for A&B antibodies before
transfusion.
• An additional test is done for Rh(D) antigen.
• About 85% of individual posses the D antigen & are
termed Rh+ve (Rh antibodies are immune type).
Cross-matching
• This test is done to detect the potential
for transfusion reaction by mixing the
doner RBSs with the recipient serum in a
test tube.
• Cross matching is completed in about 45
-60 min & is carried out in three phases :
*Immediate phase: is a check against
errors in ABO typing ,takes about 15 min & is able to detect incomplete
antibodies.
*Incubation phase :
(30-45 min in albumin )
The incubation allows a sufficient duration for
antibody uptake by cells.
*Antiglobulin phase :
Detects most incomplete antibodies in the
blood. It is done by adding antiglobulin to the
incubated test tube .Antiglobulin becomes
attached to globulin antibodies on RBCs causing
agglutination.
The most serious antibodies are those appearing
in the immediate phase ; others are less sever
clinically .
Antibody screening
• This is a trial transfusion between the
recipient serum & a commercially
supplied RBCs containing optimal
number of RBCs antigen.
• The same test is done for donner
serum , shortly after blood withdrawal.
Storage of blood
Blood is stored in special referegrators at 1-6
C. Different solutions are added to act as
preservatives & anticoagulants.
• Preservatives:
*C.P.D. : Citrate is an anticoagulant which
prevents clotting by binding calcium,
phosphate acts as a buffer & dextrose
allows RBCs to continue glycolysis to
provide ATP for metabolism & hence
survival .
Storage at 1-6 C slows the rate of
metabolism .
C.P.D. maintain 70% RBCs survival for 28
days.
*CPD-A :Addition of adenine to CPD has increased the
RBCs storage time to 35 days. Adenine allows the
RBCs to resynthesise ATP .
*Adsol (SAGM) : The half life of RBCs can be increased
to 42 days when Adsol is added. Adsol contains
sodium chloride , adenine , glucose & mannitol
Frozen storage : Blood mixed with glycerol & stored
at -79 C has an indefinite period of storage. It must
be free of glycerol before transfusion.
Effects of storage
(Stored blood is an unphysiological solution)
Effects are :
* Progressive decrease in the content of ATP
& 2,3-DPG & decreased activity of Na-K
pump.
*Reduced plasma pH.
*Other constituents can not withstand
storage , e.g.. : platelets, granulocytes&
coagulation factors.
Complications
1- Change in O2 transport :
This is because of left ward shift in
oxyhaemoglobin dissociation curve, leading to
tissue hypoxia.
2- Changes in coagulation :
A bleeding tendency is often present in
massively transfused pt. This is due to :*Delusional thrombocytopenia: At 4C platelets
are sufficiently damaged& those infused have a
reduced survival time. Platelets activity is also
reduced, being 50% after 6 hrs.,10% after 24
hrs.& 5% after 48 hrs. of storage.
*Low levels of coagulation factors :Most
factors are stable at 4C with exception of factor
V & VIII which decreases to 15 & 50% of normal,
Respectively, after 21 days of storage.
*D.I.C. : This is induced by massive
transfusion.
3-Citrate intoxication:
Citrate binds calcium & thus signs are those of
hypocalcaemia. Very high rates of infusion are
required to produce hypocalcaemia(1 unit of blood
per 5 min. )
Serum Ca. returns normal after transfusion
because citrate is rapidly metabolised by the liver.
Hypothermia, liver impairment& hyperventilation
increase the possibility of citrate intoxication.
4-Hyperkalaemia:
Serum potassium may be as high as
30mmol/L in stored blood after 21 days
of storage. A bank blood should be
given at a rate of 120 ml/min to
produce significant hyperkalaemia.
5-Hypothermia :
If core temperature declines to 30C,
ventricular arrhythmias& cardiac arrest
may occur.
6-Infusion of microagrigates :
Amount of clots& debris in stored blood
increase with duration of storage. For this
reason ,stored blood is infused through a
giving set with standard filter(170 micro
meter). Some particulates are not filtered&
enter the blood stream. ARDS after massive
transfusion may be the result of
accumulation of these particulate materials
in the lungs, resulting in vascular
obstruction.
Several filters with micro pores are now
available to remove microagrigates from
stored blood.
7- Transfusion reactions:
a). Haemolytic reactions:
It is the most serious reaction which arise
from intravascular haemolysis caused by
incompatible transfusion. It can occur after
transfusion of as little as 10 ml of blood.
Mortality is 20-60%.
Classic symptoms& signs are:
*Fever *Rigors *Chest pain *Hypotension
*Nausea *Flushing *Haemoglobinurea.
These symptoms& signs are masked by
general anaesthesia. The only signs may be
haemoglobinurea, bleeding diathesis or
hypotension.
Haemoglobinurea occurs when the plasma
level of haemoglobin reaches 150mg/100ml
plasma( Beyond the capacity of
haptoglobulin).
Management:
Mainly renal& coagulation systems are
affected.
Haemoglobin, as acid haematin,
precipitates in the distal tubules, causing
mechanical obstruction. Management is
directed towards stopping infusion,
maintaining good urinary out put through
I.V. fluid administration with diuretics,
alkalinizing urine& retaining blood for
recrossmatching.
b).Non haemolytic reactions: These are
usually less serious.
*Febrile reactions: They are due to WBCs&
have the same symptoms( but less sever) of
haemolytic reactions.
*Allergic reactions: They are caused by
foreign protein in the transfused blood.
Common symptoms are urticarea, itching&
facial flushing. Antihistamines are used to
treat these symptoms.
8- Infectivity of blood:
Many diseases can be transmitted by
blood transfusion :
*Viral: Hepatitis, HIV, cytomegalovirus
*Bacterial: Salmonella, brocella
*Spirochetal: Syphilis
*Parasitic: Malaria, filariasis.
9-Immunodepression:
Blood transfusion exerts a non specific
immunodepressive action on the recipient.
The cause is unknown, but present data
indicate that blood transfusion increases the
susceptibility to infection& enhances
progression of malignant tumors.
THANK YOU