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Haematology > Blood Transfusion > Flashcards

Blood Transfusion Flashcards

1
Q

How do we ensure safety of blood donors?

A

healthy volunteer donors Hb must be 125 if female or 135 if male and over, and weigh at least 50kg
there is a donor selection questionnaire and contact details if unwell post donation

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2
Q

How are blood donations processed?

A

bag of whole blood is centrifuged into separate component parts
undergo micro testing for HIV, Hep B,C and E, HTLV (leukaemia virus) and syphilis
red cells are stored at 4 degrees for 35 days
fresh frozen plasma is stored at 30 degrees for 3 years
platelets are stored at 22 degrees for 7 days

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3
Q

Name the different things available and uses from the blood lab?

A

blood components- red cells (anaemia), FFP (clotting factors) platelets (thrombocytopenia), cryoprecipitate (source of fibringen)

blood products - made from pools of thousands of donors usually with viral inactivation steps e.g. anti-D, prothrombin complex concentrate

blood products from pharmacy - IV Ig, human albumin, specific Ig e.g. VZV

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4
Q

What are the two most significant blood group systems?

A

ABO and Rh system

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5
Q

Give an overview of the ABO system?

A

ABO is coded for on chromosome 9
A and B are dominant for O
O is silent (no O antigen just lack of AB)
A and B are co-dominant
So group A genotype is AA or AO, B is BB or BO, AB is AB, O is OO
Group O is most commonly followed by A

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6
Q

What is Landsteiner’s law?

A

when an individual lacks the A or B antigen the corresponding antibody is produced (due to natural exposure from antigens in food and bacteria)
these naturally occurring antibodies are IgM

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7
Q

Why is the ABO system the most significant?

A

someone can have antibodies present before first exposure

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8
Q

Blood type O can receive ________

can donate to _________

A

receive: only O
donate: to A, O, B, AB

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9
Q

Blood type A can receive _________

can donate to ___________

A

receive: A or O
donate: A or AB

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10
Q

Blood type B can receive _________

can donate to _______

A

receive: B or O
donate: B or AB

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11
Q

Blood type AB can receive ______

can donate to _______

A

receive: A, AB, B or O
donate: AB

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12
Q

Explain the importance of the RhD system and what is done to avoid reactions?

A

It is very immunogenic
people can be exposed through pregnancy or blood transfusion
IgG antibodies
can then get transfusion reactions and haemolytic disease of newborn
therefore should avoid exposing RhD neg people to RhD positive blood

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13
Q

What percentage of the population is RhD positive?

A

85%

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14
Q

Explain the importance of other blood group system?

A

these are generally less immunogenic than ABO and RhD
Individuals can become sensitised to antigens through exposure from pregnancy and transfusion
repeat exposure can result in transfusion reaction

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15
Q

Explain what is done for pre-transfusion testing?

A

use reagents with known antibodies to identify antigens present on the red cell
use red cells with known antigen specificity to identify antibodies present in the plasma
look for agglutination
for other antibodies not RhD or ABO can test against reagents with several antigens and do further testing if any are positive to identify that specific antibody
IAT crossmatch: use donor cells and recipient plasma and see if agglutination, if there is agglutination then match is incompatible

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16
Q

What are the aims of pre-transfusion testing?

A

identify ABO and RhD of patient and presence of any clinically significant red cell antibodies

17
Q

What is SHOT?

A

serious hazards of transfusion

basically voluntary reporting of adverse events which is published annually with recommendations

18
Q

Acute haemolytic transfusion reactions are most serious and life threatening reactions and are due to _____________
There is __________

A

ABO incompatibility

complement activation by the antigen-antibody reaction usually caused by IgM antibodies

19
Q

What are the symptoms/ signs of AHTR?

A

rigors, lumbar pain, dyspnoea, hypotension, haemoglobinuria, renal failure

20
Q

Clinical and lab management of AHTR?

A

clinical: stop transfusion and return to lab and inform, supportive measures, repeat transfusion samples, take bloods for FBCs, coat, renal function, haemolysis, blood culture
lab: repeat testing, direct Ig test, repeat crossmatch

21
Q

What causes delayed haemolytic transfusion reactions?

A

delayed response IgG due to alloimmunisation from pregnancy or previous transfusion

22
Q

Features of delayed haemolytic transfusion reactions?

A

extravascular haemolysis 5-10 days post transfusion
patient may be anaemic and jaundiced
can detect the alloantibody at this point

23
Q

Name 6 complications of blood transfusion?

A

IMMMUNE
Acute haemolytic transfusion reactions
Delayed haemolytic transfusion reactions
Mild reactions (febrile non-haemolytic transfusion reaction and mild allergy)

NON IMMUNE
Viral transmission
bacterial transmission
transmission associated circulatory overload

24
Q

Bacterial contamination of blood is more common in what type of donation?

A

platelet donation (because it is stored at 22 degree)

25
Q

Management of bacterial contamination of blood components?

A

culture patient sample and remains of unit, treat with broad spectrum antibiotics, inform transfusion lab so other units can be quarantined

26
Q

What is TACO?

A

Transfusion associated circulatory overload

PO develops due to circulatory overload

27
Q

Risks factors for TACO?

A

elderly patients, cardiac failure, low albumin, renal impairment, fluid overload

28
Q

Clinical features of TACO?

A

resp distress within 6hrs of transfusion, raised BP, raised JVP, positive fluid balance

29
Q

Management of TACO?

A

oxygen and supportive care, diuretics

30
Q

Prevention of TACO?

A

consider slowing rates of further transfusions
consider diuretics with future transfusion
only transfuse minimum volume required
aim to identify patients ar risk before first transfusion

31
Q

What are mild transfusion reactions defined as?

A

isolated temp rise > 38 degrees of 1-2 degrees or rash only

32
Q

With mild transfusion reactions can you continue?

A

yes but must monitor for worsening

33
Q

Describe the two causes of mild transfusion reactions?

A

1) febrile non-haemolytic transfusion reaction > this is less common since leucodepletion, can consider pre-medication with paracetamol if patient suffers repeated reactions
2) mild allergy (usually due to plasma components) > can be treated with anti-histamines

34
Q

Most common ABO blood groups?

A

O is most common

followed by A

Haematology (12 decks)

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