Haematology Transfusion Flashcards
Blood Donors
- Healthy volunteer donor
- 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 - 450 ml collected, up to every 12 weeks
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
Processing
- Leucocyte depletion – reduces WCC reaction to recipiant
- Split into red cells/platelets/Plasma
- Special processes (to order): irradiation, washing, hyper-concentration
Blood components available
Plasma
Platelets (Granulocytes) – rare cases
Red cells
Plasma
Fractionated plasma proteins – albumin/clotting factors
Fresh frozen plasma (for clotting factors)
Cryoprocipitate – rich in fibrinogen
Red cells: Used for
Blood loss
Anaemia
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)
Red cells: Shelf life
35 day shelf life at 4 degrees
Platelet Concentration: Used for
Thrombocytopenia
Platelet dysfunction
Platelet Concentration: Collection process
Pooled from 4-6 donors
Platelet Concentration: Apheresis
Single donor
Platelet Concentration: Storage
22 +/- 2oC (room temp) for 5 days on an agitator (7 days if bacterial screening)
Fresh Frozen Plasma: Used for
Replacement of clotting factors
Fresh Frozen Plasma: Storage
Plasma fraction frozen to -30oC
Stored up to 3 yrs
20 mins to defrost
Infuse with 4 hours
Fresh Frozen Plasma: Virally inactivation via and used for
Children and if using large volumes:
• Methylene Blue Treatment
• Solvent detergent treatment
Cryoprecipitate: Formed
Precipitate formed when defrosting FFP – rich in fibrinogen (Factor 8)
Cryoprecipitate: Contain
Rich in fibrinogen
Factor 8
VWF
Cryoprecipitate: Used
For fibrinogen supplementation – mostly bleeding patients
Cryoprecipitate: Virally
Inactivation (methylene blue) available
Fractionated blood products: Prepared from
They are pharmaceutical products
Prepared from pooled plasma from many donors
Fractionated blood products: Contain
Albumin
Clotting factor concentrates
Intravenous immunoglobulin
Disease – specific immunoglobulin
Hazards of Transfusions
- Unavailable blood
- Transfusion transmitted infections
- Immunological reactions
- Overloading:
a. Iron
b. Fluid
Lack of Blood
WHO:
- Each year, more than 500000 women die needlessly during pregnancy or childbirth
- Severe bleeding can kill even a healthy woman with 2 hrs if she is unattended = 44% of maternal deaths in Africa
- Up to one-fourth of all maternal deaths could be saved by access to safe blood transfusion
- Also happens in developed worl – usually organisational problems
Transfusion transmitted infection: virus
HIV HBV HCV CMV HTLV1 Parovirus West Nile Virus
Transfusion transmitted infections: Protozoa
Malaria
Trypanosomes
Syphilus
Transfusion transmitted infections: Bacteria
Staphylococci (Skin)
Yersinia
Transfusion transmitted infections: Prions
CJD (4 documented cases)
Prevention of Infections:
- Donor Selection – volunteer vs. paid
- Testing of blood
- Pathogen inactivation –
- Avoiding transfusion
See pg27 for effectiveness of testing for infections
Immunological reactions: Red cells
Blood Groups: (polymorphic proteins)
• Immediate haemolysis
• Delayed Haemolysis
• Haemolytic disease of the newborn
Immunological reactions: Platelets
Post transfusion purpura
HPA – human platelet antigens
Immunological reactions: Lymphocytes/HLA (neutrophil antigens)
Graft versus host disease
Immunological reactions: Plasma Proteins
Allergy/Anaphylaxis
Donor exposure – drugs/food
Blood Groups: Inheritance
Inherited variation of red cell membrane proteins
• ABO system
• Rh system (DCE)
• MNS, K, Fy, Jk, Le, Lu
Blood Groups: Antibody reactions
Can be formed against transfused antigens
Blood Groups: Antibodies can cause haemolysis
- Of the transfused blood
- Of the recipient blood
- In the fetus/newborn (Haemolytic Disease of the Newborn
Blood Groups:The incompatible transfusion: Major Compatibility
- Recipient has antibodies against transfused blood
* E.g. group A blood given to group O patient
Blood Groups: The incompatible transfusion: Minor Compatibility
- Transfused blood contains antibodies against recipient cells
- E.g. group O blood transfused to group A patient
Most common blood groups
O then A
Rare blood groups
AB
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).
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
Universal donor
O
Universal donor for plasma
AB
Positive negativity refers to
RhD
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
White cells: Graft versus host disease (TA-GVHD)
Prevention
Gamma irradiation of cellular blood components for susceptible recipients
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
Immunological reactions: platelets post transfusion purpura treatment
High-dose ivlg 0.4g/kg for 5 days
Reactions against plasma proteins (common)
Allergic reactions
• Analphylaxis
• Rash
Febrile reactions
Iron overload 1 unit red cells contains
Iron overload 1 unit red cells contains
250mg iron
3mg/day
Cause of iron overload
Regular transfusion (several years)
Toxicity of iron overload
Heart Liver Pancreas Joints Pituitary
Treatment of iron overload
Minimise transfusion
Long term iron chelation (desferrioxamine [s/c] or deferasirox/deferiprone [oral])
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)
Transfusion associated circulatory overload: Treatment
• Slow down the infusion and give frusemide
Transfusion associated circulatory overload: Prevention
- Identify at risk patients.
- Give frusemide with transfusion
- 1 unit at a time.
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)
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
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
When to prescribe platelets
- Ensure the reason for low platelets is known
* Bone marrow failure in a well patient if plt <100x109/l
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.
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)
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
Alternatives to Transfusion:
- Avoid anaemia/blood loss
a. Reducing blood sampling
b. Preoperative optimisation
c. Tranexamic acid - Treat anaemia
a. Identify cause and treat
b. IV iron, erythropoietin - Intraoperative cell salvage
- Artificial blood substitutes?
Special Requirements:
Irradiated blood:
• To prevent
• Used for
CNV negative blood
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)
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)
Acute complications:
- Acute transfusion reaction →
a. Acute haemolysis
b. Bacterial contamination - Acute breathlessness
a. Fluid overload
b. Anaphylaxis
c. Transfusion related head injury - Minor reactions
a. Rash
b. Febrile reaction