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blood tranfusion Flashcards

1
Q

define blood group system

A

Collection of one or more RBC antigens under the control of a single gene or a cluster of closely linked homologous genes

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2
Q

what factors determine the RBC antigens structure

A

specific sequence of oligosaccharides (3-10 monosaccharides in a chain)
specific sequence of amino acids

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3
Q

how many blood group systems are there?

A

43

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4
Q

43 blood group systems contains … antigens

A

345 red cell

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5
Q

Which blood group systems are most clinically relevant

A

ABO and Rh

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6
Q

Antibodies against RBC antigens cause haemolysis resulting in: (2)

A

haemolytic transfusion reactions (HTRs)

haemolytic disease of the foetus and newborn (HDFN)

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7
Q

what are HTRs

A

where incompatible red cells are transfused i.e. transfused RBC has antigen that corresponds to patients plasma antibodies

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8
Q

what is HDFN

A

where the foetus has a different RBC antigen to it’s mother where mother produces antibody to that RBC crossing the placenta.

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9
Q

what are the two different types of antibodies?

A

naturally occurring antibodies

acquired alloantibodies

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10
Q

describe ABO antibodies

A

.naturally occuring
.Their production is stimulated when the immune system encounters the ‘missing’ ABO blood group in foods or in microorganisms.
.ABO antibodies are mostly IgM antibodies that remain as IgM antibodies

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11
Q

describe IgM antibodies

A

pentameric
The interaction between the pentameric IgM antibody and RBC antigens in vitro produces direct easily visualised clumping (agglutination) of red cells

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12
Q

what can igM antibodies cause

A

acute HTRs through activation of the complement system resulting in massive intravascular haemolysis

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13
Q

can igM antibodies cause HDFN?

A

No-igM can’t cross the placenta

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14
Q

what causes acquired antibodies to form

A

.vaccination
.exposure from mother to foetus
.incompatiable blood transfusion

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15
Q

what antibodies are associated with being acquired

A

IgG antibodies

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16
Q

describe the structure of IgG antibodies

A

Y shaped

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17
Q

true or false: IgG antibodies interaction with RBC antigens can’t be visualised in vitro

A

true

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18
Q

what causes does IgG antibodies have

A

delayed HTR
Extravascular haemolytic
HDFN

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19
Q

why can IgG antibodies cause HDFN but IgM cannot

A

IgG antibodies can cross the placenta in contrast to IgM which cannot.

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20
Q

what does the A gene code for?

A

an enzyme that adds N-acetyl galactosamine (GalNac) to the common H antigen resulting in the A antigen

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21
Q

what does the B gene code for?

A

enzyme that adds galactose (Gal) to the common H antigen resulting in the B antigen

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22
Q

why can a transfusion of blood from the wrong ABO group be fatal

A

the PATIENT has anti A or anti B antibodies which activate complement to hamolyse the red cells

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23
Q

what blood group is given in transfusion if type of patient is unknown and why?

A

O NEGATIVE- lacks both A or B antigens, therefore there is no risk of acute HTR occurring even if a patient has anti-A or anti-B antibodies.

24
Q

what is Landsteiner’s law

A

whichever ABO antigens are lacking on a given person’s RBCs, that person will always have the corresponding antibody. e.g B antigen patient has anti A (as there was no A in blood)

25
Q

when can platelets not of the same ABO blood group be given to a patient

A

when they are high-titre negative, (don’t have a high concentration of anti A or Anti B antigens)

26
Q

A patient requires FFP or cyropercipitate but ABO is unknown. Which type may be given AND WHY

A

AB-HAS NO ANTIBODIES

27
Q

Which Rh antigen is most significant

A

D

28
Q

RhD, the D allele is recessive: true or false?

A

False-D allele is dominant

29
Q

Anti-D antibodies are clinically significant as they can cause:

A 
Delayed HTRs (extravascular haemolysis) - if RhD positive red cells are transfused (resulting in anaemia, high bilirubin, jaundice)
HDFN - if a RhD negative mother is carrying a RhD positive fetus as the IgG anti-D antibodies can cross the placenta and haemolyse the RhD positive fetal RBCs.
30
Q

how can we prevent formation of anti D antibodies

A

ensuring transfusions to RhD negative patients receive RhD negative red cells and platelets transfusions

31
Q

How are RhD pregnant women with RhD positive babies treated

A

Anti D-immunoglobulin which works by destroying any RhD positive fetal RBCs in the maternal (mum’s) circulation before she can make her own anti-D antibodies (known as ‘sensitisation’)

32
Q

true or false: Red cells for transfusion should be of the same RhD type as the patient i.e. RhD negative RBCs for RhD negative patients.

A

true

33
Q

true or false: It is harmful to give a RhD positive patient RhD negative blood

A

False- no harm, just wasteful

34
Q

Group O RhD positive RBCs are used as emergency blood when a patient’s needs emergency transfusion: true or false?

A

false: Group O RhD NEGATIVE RBCs are used as emergency blood when a patient’s needs emergency transfusion

35
Q

define alloimmunity

A

Alloimmunity is an immune response to nonself antigens from members of the same species,

36
Q

true or false:Platelets for transfusion should be of the same RhD type as the patient i.e. RhD negative platelets for RhD negative patient

A

true

37
Q

FFP or cryoprecipitate of any D type can transfused regardless of the patients RhD type. Why?

A

These plasma components do not contain any RBCs.

38
Q

what is the forward group

A

ABO antigens on their RBCs

39
Q

what is the reverse group

A

ABO antibodies in their plasma

40
Q

define agglutination

A

formation of clumps of cells or inert particles by specific antibodies to surface antigenic components

41
Q

All blood donations undergo two types of testing:

A

group and screen

infection testing

42
Q

which tests are mandatory for donor blood

A

HIV,hep B,hep C, hepE,HLTV and syphillis

43
Q

what ADDITIONAL tests may be performed on donor blood

A

malaria, T.Cruzii, CMV (virus)

44
Q

what is the purpose of antibody screening

A

detect the presence of any acquired alloantibodies the patient may have developed.
(antibodies produced from exposure to foreign RBC antigen)

45
Q

name two methods of blood donation

A

whole body donation

aphaeresis (machine collects and separates blood)

46
Q

what are the 4 main blood components?

A

Red cells (‘packed red cells’)
Platelets
Fresh Frozen Plasma (FFP)
Cryoprecipitate

47
Q

what is fractionation

A

the pooling of plasma donations to form medicinal products

48
Q

what can plasma be fractioned into?

A

Human albumin solution
Immunoglobulins
Clotting factor concentrates

49
Q

what is FFP

A

FFP contains all the coagulation factors.
Transfusions of FFP are required for treatment of bleeding or to reduce the risk of bleeding in patients with coagulopathies (multiple blood clotting factor deficiencies)

50
Q

what causes coagulopathies

A

.dilution ( massive bleeding)

consumption e.g Diseminated intravascular coagulation

51
Q

what is in cyroprecipitate?

A

contains fibrinogen, Factor VIII, von Willebrand factor and Factor XIII.

52
Q

clinical needs for Human albumin solution include:

A

To replace plasma volume in patients with plasma volume loss e.g. due to burns or trauma
To replace plasma in plasma exchange e.g in the treatment of autoimmune disorders
To initiate diuresis in patient with low albumin e.g. due to liver or kidney disease

53
Q

What do prothrombin complex concentrates contain

A

Factors II, VII, IX and X.

54
Q

PCCs can be used to reverse the effect of warfarin by replacing these deficient coagulation factors: true or false

A

True: PCCs can be used to reverse the effect of warfarin by replacing these deficient coagulation factors:

55
Q

PCC’s can be used to treat:

A

major bleeding and haemorrhage

pom (17 decks)

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