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103 Theme 2 - Blood > Principles of blood transfusion > Flashcards

Principles of blood transfusion Flashcards

(45 cards)

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1
Q

What is the funadamental problem in blood transfusion?

A
  • Red cells have antigens on their surface
  • Human plasma may contain antibodies to these antigens
  • These can cause reactions - sometimes fatal
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2
Q

What antigens will each blood group have on the surface of their RBC?

A
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3
Q

What are agglutinins?

A

Naturally occurring (pentameric) IgM antibodies

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4
Q

What are ABO antibodies and how do they occur?

A
  • Antibodies to ABO antigens occur naturally due to cross reactivity with gut bacterial antigens
  • These are IgM (pentameric) antibodies able to fix complement and cause red cell lysis
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5
Q

What happens when transfusion with incompatable ABO blood occurs?

A

Transfusion of ABO incompatible blood causes intravascular lysis

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6
Q

What does intravascular lysis cause?

A

This can lead to a major life-threatening transfusion reaction causing:

  • shock, hypotension, tachycardia
  • renal failure, loin pain, haemoglobinuria
  • disseminated intravascular coagulation
  • death
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7
Q

Complete the table

A
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8
Q

What test is this?

A

Agglutination reaction

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9
Q

What is the blood group?

A

Answer: Group A

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10
Q

What is forward grouping and what is reverse grouping?

A
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11
Q

Complete the table

A
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12
Q

Put the blood groups in order form most to least common.

A

O

A

B

AB

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13
Q

What does each column test for?

Is the result positive or negative?

A

Columns (left to right):

1) Cells vs. anti-A
2) Cells vs. anti-B
3) Cells vs. anti-D
4) Control (cells vs. plasma)
5) Plasma vs. gp A cells
6) Plasma vs. gp B cells

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14
Q

What’s the blood group?

A

Answer: Group O Rh +ve

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15
Q

What are the blood groups for each patient sample?

A
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16
Q

Which blood group is protective and which is higher risk for COVID 19?

A

blood group O is protective; A is higher risk

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17
Q

What does the lab do for a sample for a ‘group and screen’?

A

–1) Test the ABO group of the red cells

–2) Screen the plasma for “atypical antibodies”

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18
Q

What are atypical antibodies and what can they cause?

A

–These arise due to sensitisation with foreign red cell antigens caused either by previous blood transfusion or by pregnancy

–Atypical antibodies can cause blood transfusion reactions if the patient is transfused with incompatible blood in the future

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19
Q

What is the antiglobulin test?

Study These Flashcards
A
  • The Coombs test is also known as the anti-globulin test
  • It uses anti-immunoglobulin antibody to agglutinate red cells
20
Q

What are the 2 types of antiglobulin tests?

21
Q

What does a direct antiglobulin test (DAT) show you?

Study These Flashcards
A
  • The DAT tells us if red cells are coated with antibody
  • It is positive after a transfusion reaction and in HDN
  • It is also positive in autoimmune haemolytic anaemia
22
Q

What does a indirectantiglobulin test (IAT) show you?

Study These Flashcards
A
  • The IAT is used in the lab for testing blood group antigens
  • It can tell us if a patient is positive for Rhesus and other blood groups
23
Q

What 2 tests are shown here?

24
Q

How does a rhesus positive person develop rhesus antibodies?

How does a rhesus negative person develop rhesus antibodies?

Study These Flashcards
A

Rh positive people cannot develop antibodies

Rh neg people can develop antibodies if they are transfused with Rh pos blood or are pregnant with a Rh pos baby

This is called Rhesus sensitisation and the antibody generated is IgG type

25
What is the most important rhesus antigen?
RhD
26
What percentage of people are rhesus negative?
15%
27
Persons who develop Rh antibodies cannot be given _______ blood
Rh Positive
28
What will happen if a mother is Rh neg is pregnant with an Rh pos fetus?
She may produce antibodies that can cross the placenta and harm the baby This is known as haemolytic disease of the newborn
29
What are the clinical consequences of haemolytic disease of the newborn?
•Anaemia, jaundice and kernicterus (brain damage)
30
How is haemolytic disease of the newborn prevented during pregnancy?
* Pregnant women have the ABO + Rh blood group check at 12 weeks * Rh-ve women (15%) receive anti-D antibody i.m. injection at 28 and 34 weeks to prevent sensitisation
31
How is haemolytic disease of the newborn prevented at birth?
Baby tested at birth and if Rh+ve, mother receives further anti-D until Kleihauer test (foetal cells) becomes negative
32
What happens to a Rh+ baby if the mother is already sensitised?
If already sensitised, then the foetus requires monitoring via trans-cranial Doppler scan and may require intra-uterine transfusions if signs of anaemia
33
What are the 4 main components in a bag of blood?
* Red cells * Buffy coat –white cells –platelets •Plasma –albumin –gamma globulins –coagulation factors •Water, electrolytes, additives
34
What components is a bag of blood seperated into?
Red cells Platelets Plasma
35
Which 4 scenarios would you give a blood transfusion in and name some examples
•Severe acute blood loss –Severe trauma e.g., road traffic accident –Massive GI blood loss –Obstetric blood loss * Elective surgery associated with significant blood loss * Medical transfusions –Cancer, chemotherapy, renal failure •Anaemia –Only for symptomatic anaemia or if refractory to haematinic replacement –Bone marrow failure e.g., myelodysplasia or aplastic anaemia -Haemoglobinopathy - thalassaemia major and sickle cell disease
36
What are the 4 components of blood?
–Red cells –Platelets –Fresh frozen plasma –Cryoprecipitate (fibrinogen)
37
What are the 3 plasma derivatives?
–Immunoglobulin –Coagulation factors (e.g., Octaplex) –Albumin
38
What are the 4 types of transfusion you can give?
* Blood components * Plasma derivatives (pooled products): * Cell salvage (rarely done during operations) * Autologous transfusion (very rarely done)
39
What are the 4 steps of compatability testing done at the lab?
* Establish ABO and Rh group * Check for atypical antibodies in patient serum * Select donor blood * Compatibility testing between donor cells and patient serum
40
What are the 3 levels of blood availability?
·O Negative (“emergency blood”) -Immediate - 5 mins ·Group Compatible (i.e. same group as patient) -10 - 15 minutes ·“Fully screened and cross-matched” -Approximately 45 minutes (but maybe hours if antibody found)
41
Name 7 blood transfusion reactions which can happen
•Major ABO incompatibilities: –Acute renal failure –Disseminated intravascular coagulation –Death * Febrile non-haemolytic reactions * Fluid overload * Anaphylaxis and severe allergic reactions * Minor allergic reactions * Delayed transfusion reactions * TRALI (transfusion related acute lung injury)
42
What are the 4 types of infections you can get from a blood transfusion and name some examples
Bacterial infections –syphilis –pyogenic infections –contamination infections (pseudomonas) Viral infections –hepatitis (B,C) –HIV –Others - HTLV, CMV –Emerging - West Nile virus Malaria Variant Creutzfeldt–Jakob disease (vCJD)
43
How can fluid overload from a blood transfusion be prevented?
–do not infuse too quickly –transfuse 1 unit over 4 hrs if elderly or evidence of heart failure –can transfuse 1 unit over 2 hours in younger patients
44
Why can fluid overload from a blood transfusion be dangerous and how is this treated?
–can cause acute pulmonary oedema –treat with diuretics (frusemide) to remove fluid
45
What is iron overload and how is it treated?
–haemosiderosis = iron overload –iron deposited in tissues (liver, heart, pancreas, skin) –can treat by iron chelation

103 Theme 2 - Blood (10 decks)

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