36 - Blood transfusion Flashcards by David Thomas

Whole blood can be separated into what components?

RBCs
Platelets
Plasma

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

Leucodepletion

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

Fresh frozen plasma

Cryoprecipitate

Fractionation

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What products would there be after fractionation of plasma

Factor concentrates (FVIII, FIX, prothrombin)
Albumin
Immunoglobulin

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Facts about 1 unit RBC

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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Transfusion threshold (trigger) definition

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

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Mechanisms of adaption to anaemia

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

After longterm, chronic anaemia

The kidneys

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Alternatives to RBC transfusions

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

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When to give RBCs

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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Management of chronic anaemia

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

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Threshold levels for chronic anaemia

80-100g/dl

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Thrombocytopenic definition

Deficiency in platelets in the blood

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Iron overload - at risk group

Problem with patients on regular transfusions (thalassaemias)

Our aim with thalassaemia is to suppress endogenous erythropoiesis

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Complications of iron overload

Cardiomyopathy

Liver failure

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Iron chelation is to

Reduce the complications of iron overload

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Haemochromatosis definition

Iron overload

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Platelet storage

Stored at room temperature (22 degrees)

Shelf-life 5 days from collection

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How many donations to one patient?

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Usual transfusion time for platelets

30 mins/unit

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Causes of thrombocytopenia

Massive haemorrhage
Bone marrow failure
Prophylaxis for surgery

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Contraindications for thrombocytopenia

Heparin induced thrombocytopenia & thrombosis

Thrombotic thrombocytopenic purpura

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Fresh frozen plasma - storage

-30 degrees for 24 months

Thawed immediately before use (20-30 mins)

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FFP - usual transfusion time

30 mins/unit

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Indications for FFP transfusion

Coagulopathy with bleeding/surgery Massive haemorrhage Thrombotic thrombocytopenic purpura

When not to transfuse FFP

Warfarin reversal Replacement of single factor deficiency

Special requirements for transplant

CMV free | Children

Tests to do on patients before transfusion

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)

Crossmatching testing

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

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

RBC units in compatible | Risk of acute haemolysis

Acute transfusion reactions

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

Delayed transfusion rxns

Immunological - transfusion-associated graft-versus-host disease (TA-GvHD) Post transfusion purpura Non-immunological - transfusion transmitted infection (TTI) viral or prion

Time scale for acute / delayed transfusions rxns

24hr delayed

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

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

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

Severe reactions during transfusion - first 15mins Mild occur later before end of transfusion Fatal in 20-30%

Acute haemolytic reaction - ABO incompatibility - signs and symptoms

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

Delayed haemolytic reaction - time of onset

3-14 days following transfusion

Delayed haemolytic reaction - clinical features

Fatigue Jaundice Fever

Delayed haemolytic reaction - lab findings

Drop in Hb Increased LDH Increased indirect bilirubin Direct antiglobulin test = positive

Delayed haemolytic reaction - why does it occur

Delayed haemolytic reaction is due IgG against RBC antigens than ABO The antibodies are formed after the transfusion

What is Coomb's test?

Anti-human globulin test to detect incomplete IgG antibodies

Steps in Coomb's test

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

Transfusion related acute lung injury - rate of fatalities, why

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

Transfusion related acute lung injury - antibodies of donor

anti-HLA | anti-HNA

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

Activated WBC lodge in pulm. capillaries Release substances that cause endothelial damage and capillary leak

TRALI - steps for diagnosis

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

TRALI - treatment

Supportive ``` Mild = supplemental oxygen Severe = mechanical ventilation & ICU support ``` Most recover between 72-96 hours

TRALI - lab investigations

Donor tested for HLA and granulocyte antibodies Recipient tested for expression of neutrophil antigens

Transfusion-associated circulatory overload (TACO) - presentation

``` Symptoms: sudden dyspnea Orthopnoea Tachycardia Hypertension Hypoxemia ``` Signs: Raised BP Elevated jugular venous pulse

Transfusion-associated circulatory overload (TACO) - risk factors

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

Comparing TRALI with TACO - type of component

Usually plasma or platelets Any

Comparing TRALI with TACO - BP

Lower in TRALI Often raised in TACO

Comparing TRALI with TACO - temperature

Often raised in TRALI Normal in TACO

Comparing TRALI with TACO - Echo

Normal Abnormal

Comparing TRALI with TACO - diuretic use

Worsens Improves

Comparing TRALI with TACO - fluid loading

Improves Worsens

Allergic rxns to transfusion

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

Anaphylaxis

Severe, life-threatening rxn soon after transfusion Wheeze/asthma, higher pulse, low BP (shock) Laryngeal/facial oedema

Anaphylaxis - investigations

Quantification of IgA, testing for anti-IgA antibodies

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

During or soon after transfusion Fever ± shakes/rigors ± upped pulse Unpleasant but not life threatening

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

Cytokine that accumulate during storage of blood components Less of an issue since leucodepletion Self-limited rxn

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

Discontinue transfusion until you exclude 'wrong blood' or bacterial infection