blood transfusion Flashcards

1
Q

why tranfuse blood

A

low levels of ‘blood’

  • bleeding
  • failure or production
  • (excess rate destruction)
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2
Q

why are blood groups a thing

A

arise from antigens
red cell antigens are expressed on cell surface
can provoke antibodies

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3
Q

ABO blood groups

A

blood group A: A antigens on surface
blood group B: no A antigens, have B

some are AB and have mix of A and B antigens

group O - null phenotype - dont have A or B

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4
Q

ABO blood group antigens

A

ABO gene encodes glycosyltransferase that sticks a partic sugar on end of sugar chain

A and B genes code for different transferase enzymes
O gene is non-functional allele - nothing is put on (recessive gene)

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5
Q

what antibodies are present for each ABO blood group

A

if blood group A on surface red cells then have antibodies against blood group B

if blood group B have antibodies against A

if O then antibodies against A and B

if AB then no antibodies against A and B

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6
Q

immune tolerance

A

immune system can distinguish between self and non-self

in utero if immune system comes across antigens which should be there (encoded by own genome) it will delete any activity against it and induce tolerance

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7
Q

anti-A/B are naturally occuring

A

Usually only develop antibody against antigen if exposed to it later in life

ABO antigens are unusual in that they are encoded by most bacteria in bowels and so are encountered
IgM formed against them as they are sugars and not proteins (so not IgG)

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8
Q

who can group A receive red cells from

A

A

O

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9
Q

who can group B receive red cells from

A

B

O

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10
Q

who can group AB receive red cells frmo

A

A
B
AB
O

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11
Q

who can group O receive red cells from

A

O

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12
Q

who can group A receive plasma from

A

A

AB

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13
Q

who can group B receive plasma from

A

B

AB

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14
Q

who can group AB receive plasma frmo

A

AB

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15
Q

who can group O receive plasma from

A

A
B
AB
O

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16
Q

RhD two genes

A

RHD gene

RHCE gene

17
Q

DD

A

positive for RHD gene

18
Q

dd

A

negative for RHD gene

19
Q

anti-RhD

A

RhD negative individuals can make anti-D if exposed to RhD+ cells e.g. infusion, pregnant

20
Q

what does anti-d cause

A

transfusion reactions 2nd in severity to ABO but can also cause haemolytic disease of newborn

21
Q

blood donors screening

A
medical history, prev transfusion 
sex
age 
travel
tested for ABO and Rh blood groups 
screened for HepB, C and E, HIV, syphilis
22
Q

blood components: plasma

A

clotting factors
albumin
antibodies

23
Q

blood components: buffy coat

A

platelets

white cells/leucocytes

24
Q

indications for red cell transfusions

A

corrects severe acute anaemia
improve QoL in pt with otherwise incorrectable anaemia
prepare pt for surgery or speed up recovery
reverse damage caused by pts own red cells e.g. sickle cell

25
Q

RBC transfusion

A

stored in fridge 4C
transfuse over 2-4hrs

1 unit increments ~5g/L

26
Q

platelet transfusion

A

1 dose = 4 doners
stored ~22C, shelf life 7days
transfuse over 20-30mins

27
Q

platelet uses

A

massive haemorrhage
bone marrow failure
surgical prophylaxis
cardiopulmonary bypass (if bleeding)

28
Q

plasma components: fresh frozen plasma

A

stored frozen, need 30mins to thaw

indications: massive haemorrhage, DIC with bleeding, prophylactic

29
Q

plasma components: cyroprecipitate

A

fibrinogen concentrate

stored frozen, 20min to thaw

30
Q

coombs test

A

try to detect antibodies on RBC surface

31
Q

development of maternal anti-d antibodies

A

mums can develop antibodies against foreign antigens that are carried by their babies and been encoded by paternal alleles e.g. RhD system

fetal red cells leak across plasma and mum picks up foreign cells and forms antibody which can cross placenta (as usually IgG - protein)

cause allo-immune haemolysis in baby –> anaemia, die

32
Q

preventing haemolytic disease of newborn

A

prophylactic anti-D

sensitising events
routine at 28/40