Transcript Blood Groups and Blood Transfusion

Blood Groups and
Blood Transfusion
Dr Stuart Laidlaw
Haematology
Royal Hallamshire Hospital
Red blood cells
• Provide intravascular volume and O2
carrying capacity.
• Transfusion of red cells can be life-saving in
situations of acute intravascular volume
loss, e.g. trauma, surgery
Red blood cells
• Although red cells have a limited life-span,
transfusion to another individual is a form
of tissue transplantation, with similarities to
kidney, heart and bone marrow
transplantation
• Compatibility between donor and recipient
is vital or rejection will occur
Red Cells
• Carry on the surface of their membrane
many different proteins which differ
between individuals
• These are the red cell antigens
• Inherited
• Over 400 different systems of red cell
antigens
• Only 2 very important: ABO and Rhesus
ABO blood group system
• 4 blood groups: A, B, AB and O
• O is recessive, so O = 0,0
• A= AA or AO, B=BB or BO, AB= AB
O= 45%, A= 40%,B=12%, AB= 3%
ABO blood group system
• ABO unusual antigens: carbohydrate, not
protein
• Naturally occuring antibodies from age 6
months
• IgM antibodies in plasma, don’t cross
placenta
• IgM antibodies fix complement to C9, so
transfusion reactions very severe
ABO blood group
• Can type cells as A, B or AB, using
antibodies: anti-A and anti-B.
If react with neither =group O
• Can type serum as double check
O serum will contain anti-A and anti-B
AB serum will not contain any antibody
A will contain anti-B, B will contain anti-A
Rhesus blood group system
• Complex series of C,D and E antigens
• D/d by far most important
• D is a null gene, no protein product, so no
anti-d possible
• D is dominant, so D = DD or Dd
• 15% population dd = d = d negative
Rhesus blood group system
• Women who are rhesus negative (dd) have
babies that carry paternal antigens, such as
D.
• If mother exposed to D red cells will make
IgG anti-D
• Anti-D crosses placenta and haemolyses
babies red cells: can result in in-utero death
and need for in-utero blood transfusion
Rhesus blood group
• It is so vital that women of childbearing age are
not exposed to wrong rhesus type blood that
everyone receives rhesus, as well as ABO,
compatible blood.
• All women have rhesus blood type determined at
each conception.
• Anti-D given to D negative mothers to prevent
sensitisation
Other blood groups
• Many in number
• Infrequent problem
• Only likely to have been sensitised if had
previous blood transfusion (occasionally by
pregnancy)
• Can cause major problems with finding
compatible blood
Group and Save
• Determine ABO group: cells and serum
• Determine Rh D status, using two different
reagents
• Screen serum for presence of preformed
antibodies to any blood group
Cross match
• Specifically determine compatibility between
donor red cells and recipients serum
• Very important if known antibodies or multiple
previous transfusions
• If group and screen neg X 2 may be unnecessary,
use electronic cross-match
Indications for transfusion
• Hypovolaemia due to loss blood
• Severe anaemia with symptoms due to
inadequate oxygenation of tissues
• Anaemia that cannot be corrected by bone
marrow function
Indications for transfusion
• Not indicated for iron deficiency or B12/
folate deficiency.
• Not indicated for minor blood loss,
especially if fit and healthy
(transfusion trigger = 8 g/dl)
• Not indicated for asymptomatic anaemia
Hazards of transfusion
• Blood is tissue from another individual
• Transfusion is potentially fatal, although
used properly can, and does save lives
Early hazards
• ABO incompatibility reaction – can be
rapidly fatal
• Fluid overload, pulmonary oedema
• Febrile reactions, urticarial reactions,
occasionally life threatening respiratory
failure
• Bacterial and malerial infection
Late hazards
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Rh D and other antibody sensitisation
Delayed transfusion reaction
Viral infection: Hepatitis B, C, HIV
? Prion infection: nvCJD
Iron overload: cardiac, hepatic and
endocrine damage
Alternatives to transfusion
• Treat anaemia pre-op
• Use transfusion trigger
• Stop anti-platelet and anti-coagulant drugs
• Consider intra-operative cell salvage and reinfusion
Alternatives to transfusion
• Consider pre-and post- operative erythropoietin
• Consider individual pre-donation of red cells
• Currently no universally available alternatives to
blood
?O2 carrying solutions, ? Artificial/ recombinant
haemoglobin polymers
Other components
• Blood is not only red cells
• Also platelets and plasma
• Plasma can be used as it is, or fractionated
to produce concentrates of specific
components, e.g. factor VIII or IX
• White cells only rarely used, as antibiotics
so potent!
Fresh frozen plasma
• Plasma frozen within 6 hours of collection
• Contains all the coagulation proteins and
inhibitors
• Used if massive transfusion and dilutional
coagulopathy, in liver disease and DIC
Cryoprecipitate
• Rich in fibrinogen
• Used in DIC and massive transfusion if
specific lack of fibrinogen
Platelets
• Correct bleeding due to thrombocytopenia
• Work for lack of production or perippheral
consumption
• Not useful if deficiency is due to immune
anti-platelet antibody
Albumin
• Useful if oedema due to lack oncotic
pressure in liver disease or nephrotic
syndrome
• Use currently declining rapidly
Anti-D globulin
• Collected from people deliberately
sensitised to D
• Used to prevent Rh D disease in Rh d
women in pregnancy, after childbirth,
miscarriage, abdominal trauma in
pregnancy and TOP
Intravenous immunoglobulin
• Pooled immunoglobulin
• Used for immunodeficiency, congenital or
acquired
• Used in some auto-immune diseases