Flashcards in Haematology Transfusion Deck (69):
1
Blood Donors
1. Healthy volunteer donor
2. Age 17-70 (no age limit for regular donors)
a. Medically assessed
i. History
ii. Medication
iii. Travel
b. Fingerprick Hb
i. Women >12.5
ii. Men >13.5 g/dl
3. 450 ml collected, up to every 12 weeks
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Apheresis donation and therapy
• Selective removal of the component required platelets or plasma (occasionally red cells)
• Up to 3 adult doses of platelets/donor visit
• Also used for therapeutic removal of plasma/WBC/platelets
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Processing
• Leucocyte depletion – reduces WCC reaction to recipiant
• Split into red cells/platelets/Plasma
• Special processes (to order): irradiation, washing, hyper-concentration
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Blood components available
Plasma
Platelets (Granulocytes) – rare cases
Red cells
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Plasma
Fractionated plasma proteins – albumin/clotting factors
Fresh frozen plasma (for clotting factors)
Cryoprocipitate – rich in fibrinogen
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Red cells: Used for
Blood loss
Anaemia
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Red cells: Storage
In additive solution
• 280+/-60 ml (slightly more concentrated)
• 0.5-0.7 haematocrit
Risk of bacterial infection post refrigeration (only 4hrs transfusion time)
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Red cells: Shelf life
35 day shelf life at 4 degrees
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Platelet Concentration: Used for
Thrombocytopenia
Platelet dysfunction
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Platelet Concentration: Collection process
Pooled from 4-6 donors
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Platelet Concentration: Apheresis
Single donor
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Platelet Concentration: Storage
22 +/- 2oC (room temp) for 5 days on an agitator (7 days if bacterial screening)
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Fresh Frozen Plasma: Used for
Replacement of clotting factors
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Fresh Frozen Plasma: Storage
Plasma fraction frozen to -30oC
Stored up to 3 yrs
20 mins to defrost
Infuse with 4 hours
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Fresh Frozen Plasma: Virally inactivation via and used for
Children and if using large volumes:
• Methylene Blue Treatment
• Solvent detergent treatment
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Cryoprecipitate: Formed
Precipitate formed when defrosting FFP – rich in fibrinogen (Factor 8)
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Cryoprecipitate: Contain
Rich in fibrinogen
Factor 8
VWF
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Cryoprecipitate: Used
For fibrinogen supplementation – mostly bleeding patients
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Cryoprecipitate: Virally
Inactivation (methylene blue) available
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Fractionated blood products: Prepared from
They are pharmaceutical products
Prepared from pooled plasma from many donors
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Fractionated blood products: Contain
Albumin
Clotting factor concentrates
Intravenous immunoglobulin
Disease – specific immunoglobulin
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Hazards of Transfusions
1. Unavailable blood
2. Transfusion transmitted infections
3. Immunological reactions
4. Overloading:
a. Iron
b. Fluid
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Lack of Blood
WHO:
1. Each year, more than 500000 women die needlessly during pregnancy or childbirth
2. Severe bleeding can kill even a healthy woman with 2 hrs if she is unattended = 44% of maternal deaths in Africa
3. Up to one-fourth of all maternal deaths could be saved by access to safe blood transfusion
4. Also happens in developed worl – usually organisational problems
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Transfusion transmitted infection: virus
HIV
HBV
HCV
CMV
HTLV1
Parovirus
West Nile Virus
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Transfusion transmitted infections: Protozoa
Malaria
Trypanosomes
Syphilus
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Transfusion transmitted infections: Bacteria
Staphylococci (Skin)
Yersinia
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Transfusion transmitted infections: Prions
CJD (4 documented cases)
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Prevention of Infections:
1. Donor Selection – volunteer vs. paid
2. Testing of blood
3. Pathogen inactivation –
4. Avoiding transfusion
See pg27 for effectiveness of testing for infections
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Immunological reactions: Red cells
Blood Groups: (polymorphic proteins)
• Immediate haemolysis
• Delayed Haemolysis
• Haemolytic disease of the newborn
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Immunological reactions: Platelets
Post transfusion purpura
HPA – human platelet antigens
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Immunological reactions: Lymphocytes/HLA (neutrophil antigens)
Graft versus host disease
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Immunological reactions: Plasma Proteins
Allergy/Anaphylaxis
Donor exposure – drugs/food
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Blood Groups: Inheritance
Inherited variation of red cell membrane proteins
• ABO system
• Rh system (DCE)
• MNS, K, Fy, Jk, Le, Lu
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Blood Groups: Antibody reactions
Can be formed against transfused antigens
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Blood Groups: Antibodies can cause haemolysis
• Of the transfused blood
• Of the recipient blood
• In the fetus/newborn (Haemolytic Disease of the Newborn
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Blood Groups:The incompatible transfusion: Major Compatibility
• Recipient has antibodies against transfused blood
• E.g. group A blood given to group O patient
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Blood Groups: The incompatible transfusion: Minor Compatibility
• Transfused blood contains antibodies against recipient cells
• E.g. group O blood transfused to group A patient
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Most common blood groups
O then A
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Rare blood groups
AB
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The basis of the ABO blood group system: explanation
• Virtually all humans express the H antigen on the surfaces of their red cells. This is therefore not antigenic = Group O
• A transferase (alpha – 3-N-acetyl-D galactosaminyltransferase) converts H to A (A and H expressed)
• B transferase (alpha – 3-N-acetyl-D galactosyltransferase) converts the H antigen into the B antigen (B and h expressed).
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Importance of the ABO system:
• Humans form antibodies against the ABO antigens they lack
• Naturally occurring antibodies
• Stimulated by micro-organisms expressing glycoproteins similar to the ABO antigens
• Usually present by 4 months of age
• Antibodies can cause immediate haemolysis
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Universal donor
O
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Universal donor for plasma
AB
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Positive negativity refers to
RhD
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White cells: Graft versus host disease (TA-GVHD)
• Donor T cells react against the recipient
• Immunodeficient recipient or of close HLA type to the donor
• Fever, skin rash, hepatitis, diarrhoea, pancytopenia
• Usually fatal but preventable
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White cells: Graft versus host disease (TA-GVHD)
Prevention
Gamma irradiation of cellular blood components for susceptible recipients
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Immunological reactions: platelets post transfusion purpura
Systems of human platelet antigens (HPa)
Anti HPA antibodies detectable in the patient’s serum.
Purpura, bleeding and thrombocytopenia
5-12 days after transfusion
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Immunological reactions: platelets post transfusion purpura treatment
High-dose ivlg 0.4g/kg for 5 days
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Reactions against plasma proteins (common)
Allergic reactions
• Analphylaxis
• Rash
Febrile reactions
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Iron overload 1 unit red cells contains
Iron overload 1 unit red cells contains
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250mg iron
3mg/day
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Cause of iron overload
Regular transfusion (several years)
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Toxicity of iron overload
Heart
Liver
Pancreas
Joints
Pituitary
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Treatment of iron overload
Minimise transfusion
Long term iron chelation (desferrioxamine [s/c] or deferasirox/deferiprone [oral])
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Transfusion associated circulatory overload: Epi
• Greatest cause of transfusion in UK
• Occurs late in infusion, uncommon in clinical areas experienced in blood transfusion
• Early signs can be detected (raised pulse and BP at 15 mins)
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Transfusion associated circulatory overload: Treatment
• Slow down the infusion and give frusemide
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Transfusion associated circulatory overload: Prevention
• Identify at risk patients.
• Give frusemide with transfusion
• 1 unit at a time.
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The transfusion process
• ABO Grouping
• Antibody screen
• Cross-match (mix donor cells + recipient serum)
• Cross check with previous records (send second sample if no previous sample)
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Causes of ABO incompatibility:
• Almost always due to patient receiving blood meant for another recipient
• Almost always preventable
• Most common errors:
o Failure to check patient identity at the bedside against the unit to be transfused
o Labelling sample tube away from the patient
o Sample transposition in laboratory
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When to transfuse red cells
• Acute blood loss >30% of blood volume
• Symptomatic anaemi (usually <7g/dl)
• It is better to treat the cause of the anaemia than to transfuse in most circumstances
• Investigate cause of anaemia before transfusion
• It may be dangerous to transfuse patients with B12 or folate deficiency, a paraprotein or sickle cell disease without consulting a haematologist
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When to prescribe platelets
• Ensure the reason for low platelets is known
• Bone marrow failure in a well patient if plt <100x109/l
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When NOT to prescribe platelets
• Consumption of platelets (e.g. ITP, drug induced) unless major bleeding.
• TTP (Thrombocytopenic thrombotic purpura)
• Irreversible marrow failure (e.g. aplastic anaemia) – only transfuse if bleeding.
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Indications for FFP
For clotting factor replacement:
• Coagulation factor deficiencies when specific factor concentrates are not available
• Multiple coagulation factor deficiencies
→Liver disease
→ Diseminated intravascular coagulation
→ Massive transfusion
• Warfarin reversal with severe bleeding (PC concentrate is preferred choice)
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Indications for cryoprecipitate
• Fibrinogen supplementation
• If there is bleeding and a fibrinogen level <1.5 g/l
• E.g. DIC advanced liver disease, massive blood transfusion, obstetric bleeding and reversal of fibrinolytic therapy
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Alternatives to Transfusion:
1. Avoid anaemia/blood loss
a. Reducing blood sampling
b. Preoperative optimisation
c. Tranexamic acid
2. Treat anaemia
a. Identify cause and treat
b. IV iron, erythropoietin
3. Intraoperative cell salvage
4. Artificial blood substitutes?
66
Special Requirements:
Irradiated blood:
• To prevent
• Used for
CNV negative blood
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Irradiated blood:
• To prevent
• Used for
Prevents GvHD
• Haematology patients (specific conditions and treatments)
• Congenital T cell immunodeficiency
• Intrauterine transfusion/neonatal exchange transfusion
• (Transfusion of blood from a relative)
68
CNV negative blood
Unit does not have anti-CMV antibodies
Neonates under 28 days post term
Elective transfusion in pregnancy (not needed for obstetric haemorrhage)
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