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Clinical Pathology > 36 - Blood transfusion > Flashcards

36 - Blood transfusion Flashcards

1
Q

Whole blood can be separated into what components?

A

RBCs
Platelets
Plasma

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2
Q

What process is done to go from whole blood to RBC?

A

Leucodepletion

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3
Q

What can be done to plasma after separation from whole blood?

A

Fresh frozen plasma

Cryoprecipitate

Fractionation

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4
Q

What products would there be after fractionation of plasma

A

Factor concentrates (FVIII, FIX, prothrombin)
Albumin
Immunoglobulin

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5
Q

Facts about 1 unit RBC

A

4 degrees storage for 35 days

Most plasma removed for high [RBC]

Usual transfusion time 90mins to 3 hours

4 hour limit from removal from cold storage to end of transfusion

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6
Q

Transfusion threshold (trigger) definition

A

Lowest [Hb] that is not associated with symptoms of anaemia

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7
Q

Mechanisms of adaption to anaemia

A 
Increase CO
Increased cardiac artery blood flow
Increased oxygen extraction
Increase RBC 2,3 DPG
Increase production of EPO
Increase erythropoiesis
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8
Q

Production of EPO and an increase in erythropoiesis occurs when and by which organ?

A

After longterm, chronic anaemia

The kidneys

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9
Q

Alternatives to RBC transfusions

A

Give iron
Give B12 and folate
Erythropoietin treatment for patients with renal disease

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10
Q

When to give RBCs

A

Think about necessity - class III on BCSH is 30-40% reduction in blood volume - start thinking about it here.

Necessary >40% (at class IV)

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11
Q

Management of chronic anaemia

A

Symptomatic relief
Improvement of quality of life
Prevention of ischaemic organ damage

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12
Q

Threshold levels for chronic anaemia

A

80-100g/dl

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13
Q

Thrombocytopenic definition

A

Deficiency in platelets in the blood

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14
Q

Iron overload - at risk group

A

Problem with patients on regular transfusions (thalassaemias)

Our aim with thalassaemia is to suppress endogenous erythropoiesis

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15
Q

Complications of iron overload

A

Cardiomyopathy

Liver failure

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16
Q

Iron chelation is to

A

Reduce the complications of iron overload

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17
Q

Haemochromatosis definition

A

Iron overload

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18
Q

Platelet storage

A

Stored at room temperature (22 degrees)

Shelf-life 5 days from collection

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19
Q

How many donations to one patient?

A

4

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20
Q

Usual transfusion time for platelets

A

30 mins/unit

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21
Q

Causes of thrombocytopenia

A

Massive haemorrhage
Bone marrow failure
Prophylaxis for surgery

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22
Q

Contraindications for thrombocytopenia

A

Heparin induced thrombocytopenia & thrombosis

Thrombotic thrombocytopenic purpura

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23
Q

Fresh frozen plasma - storage

A

-30 degrees for 24 months

Thawed immediately before use (20-30 mins)

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24
Q

FFP - usual transfusion time

A

30 mins/unit

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25
Q

Indications for FFP transfusion

A

Coagulopathy with bleeding/surgery

Massive haemorrhage

Thrombotic thrombocytopenic purpura

26
Q

When not to transfuse FFP

A

Warfarin reversal

Replacement of single factor deficiency

27
Q

Special requirements for transplant

A

CMV free

Children

28
Q

Tests to do on patients before transfusion

A

ABO and Rh(D) group
Patient’s plasma screened for Ig against other clinically significant blood group antigens (compare vs panel of RBCs - if -ve no further testing)

29
Q

Crossmatching testing

A

Aliquots of donor red cells mixed with normal and see if reaction (agglutination or haemolysis)

30
Q

If there is a reaction to crossmatch test what does that mean? what can happen?

A

RBC units in compatible

Risk of acute haemolysis

31
Q

Acute transfusion reactions

A

Immunological - acute haemolytic transfusion reaction ABO incompatibility
Allergic/anaphylactic reaction
TRALI - transfusion-related acute lung injury

Non-immunological - bacterial contamination
TACO (transfusion associated circulatory overload)
Febrile non-haemolytic transfusion rxn

32
Q

Delayed transfusion rxns

A

Immunological - transfusion-associated graft-versus-host disease (TA-GvHD)
Post transfusion purpura

Non-immunological - transfusion transmitted infection (TTI) viral or prion

33
Q

Time scale for acute / delayed transfusions rxns

A

24hr delayed

34
Q

What is the acute haemolytic reaction-ABO incompatibility? And what is it frequency?

A

1:25k

  1. Release of free Hb
  2. Hb deposition in distal renal tubules = acute liver failure
  3. stimulation of coagulation results in microvascular thrombosis
  4. stimulates cytokine storm
  5. NO released resulting in generalised vasoconstriction
35
Q

Acute haemolytic reaction - ABO incompatibility - reactions timings and % fatality

A

Severe reactions during transfusion - first 15mins

Mild occur later before end of transfusion

Fatal in 20-30%

36
Q

Acute haemolytic reaction - ABO incompatibility - signs and symptoms

A 
Fever and chills
Back pain
Infusion pain
Hypotension/shock
Haemoglobinuria (in anaesthetised patients)
Increased bleeding (DIC)
Chest pain
Sense of 'impending death'
37
Q

Delayed haemolytic reaction - time of onset

A

3-14 days following transfusion

38
Q

Delayed haemolytic reaction - clinical features

A

Fatigue
Jaundice
Fever

39
Q

Delayed haemolytic reaction - lab findings

A

Drop in Hb
Increased LDH
Increased indirect bilirubin

Direct antiglobulin test = positive

40
Q

Delayed haemolytic reaction - why does it occur

A

Delayed haemolytic reaction is due IgG against RBC antigens than ABO

The antibodies are formed after the transfusion

41
Q

What is Coomb’s test?

A

Anti-human globulin test to detect incomplete IgG antibodies

42
Q

Steps in Coomb’s test

A
  1. RBCs coated with IgG antibody e.g. anti-Rh in a Rh positive patient
  2. Anti-human globulin test (AHG) added
  3. Visible agglutination
43
Q

Transfusion related acute lung injury - rate of fatalities, why

A

5-10% fatal
Donor has antibodies to recipient’s leucocytes
Associated with transfusion of plasma rich components (platelets, FFP)

44
Q

Transfusion related acute lung injury - antibodies of donor

A

anti-HLA

anti-HNA

45
Q

Transfusion related acute lung injury - how does it damage lungs?

A

Activated WBC lodge in pulm. capillaries

Release substances that cause endothelial damage and capillary leak

46
Q

TRALI - steps for diagnosis

A
  1. Presence of acute lung injury = hypoxia, bilateral chest x-ray infiltrates, absence of circulatory overload
  2. occurs within 6 hrs of transfusion
47
Q

TRALI - treatment

A

Supportive

Mild = supplemental oxygen
Severe = mechanical ventilation & ICU support

Most recover between 72-96 hours

48
Q

TRALI - lab investigations

A

Donor tested for HLA and granulocyte antibodies

Recipient tested for expression of neutrophil antigens

49
Q

Transfusion-associated circulatory overload (TACO) - presentation

A 
Symptoms: sudden dyspnea
Orthopnoea
Tachycardia
Hypertension
Hypoxemia

Signs:
Raised BP
Elevated jugular venous pulse

50
Q

Transfusion-associated circulatory overload (TACO) - risk factors

A

Elderly
Small children

Patients with poor:
Left ventricular function
Increased volume of transfusion
Increased rate of transfusion

51
Q

Comparing TRALI with TACO - type of component

A

Usually plasma or platelets

Any

52
Q

Comparing TRALI with TACO - BP

A

Lower in TRALI

Often raised in TACO

53
Q

Comparing TRALI with TACO - temperature

A

Often raised in TRALI

Normal in TACO

54
Q

Comparing TRALI with TACO - Echo

A

Normal

Abnormal

55
Q

Comparing TRALI with TACO - diuretic use

A

Worsens

Improves

56
Q

Comparing TRALI with TACO - fluid loading

A

Improves

Worsens

57
Q

Allergic rxns to transfusion

A

Urtical rash ± wheeze
Often not severe
Hypersensitive to random plasma protein

58
Q

Anaphylaxis

A

Severe, life-threatening rxn soon after transfusion

Wheeze/asthma, higher pulse, low BP (shock)

Laryngeal/facial oedema

59
Q

Anaphylaxis - investigations

A

Quantification of IgA, testing for anti-IgA antibodies

60
Q

Febrile non-haemolytic transfusion reactions (FNHTR) - onset, presentation

A

During or soon after transfusion

Fever ± shakes/rigors
± upped pulse

Unpleasant but not life threatening

61
Q

Febrile non-haemolytic transfusion reactions (FNHTR) - why?

A

Cytokine that accumulate during storage of blood components

Less of an issue since leucodepletion

Self-limited rxn

62
Q

Febrile non-haemolytic transfusion reactions (FNHTR) - what to do

A

Discontinue transfusion until you exclude ‘wrong blood’ or bacterial infection

Clinical Pathology (65 decks)

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