Blood Transfusion Flashcards
What does the ABO gene encode?
Glycotransferase (carb + transferase protein)
What is the A antigen?
N-acetyl-galactosamine
What is the B antigen?
Galactose
What is the O antigen?
No extra antigen upon the basic unit
Of the ABO groups what is dominant?
A and B co-dominant
What antibodies does each ABO group have?
Ab against the antigens it does not have
O - against A and B
A - against B
B - against A
AB - none
Define immune tolerance
Prevention of an immune response against a specific antigen
When do you develop IgM against A/B antigens?
As soon as exposed to bacteria of the gut, will form these antibodies
What kind of antibodies are the ones against A and B antigens?
IgM - stay like this
IgM can provoke the complement cascade
What is the reaction that occurs when Ab bind their antigen?
Agglutination
Who can A patients receive red cells from?
A, O
Who can B patients receive red cells from?
B, O
Who can AB patients receive red cells from?
All groups
Who can O receive red cells from?
O
Who are the universal recipients and donors of red cells?
Donor - O
Recipient - AB
Who can A patients receive FFP from?
A, AB
Who can B patients receive FFP from?
B, AB
Who can AB patients receive FFP from?
AB
Who can O patients receive FFP from?
A, B, AB, O
What is rhesus?
Transmembrane protein (ion channel for nitric oxide) that is very immunogenic
Being rhesus negative/positive is autosomal recessive
Negative (dd)
What do rhesus -ve individuals produce if they are exposed to rh +ve cells?
Anti-D
What can Anti-D cause?
Transfusion reactions or haemolytic disease of the newborn
What is involved in screening of blood donors?
Behaviour - age, sex, travel, tattoos etc.
ABO/Rh groups
Hep B/C/E/HIV/syphilis
Variably screened for HTLV1, malaria, west nile virus, zika virus
What are apheresis donors?
Donors who will give off just a certain component of blood (e.g. platelets or clotting factors)
What are the three blood components and what comes from each?
Red cells
Buffy coat (platelets, leucocytes)
Plasma (albumin, clotting/coagulation factors, Abs)
FFP is imported now - true or false?
True due to CJD
What are indications for red cell transfusion?
Correct severe acute anaemia (which may otherwise –> organ failure)
Improve QoL in anaemia
Prepare for surgery/speed up recovery
Sickle cell dx etc.
Why might someone receive platelets?
Massive haemorrhage
Bone marrow failure (to prevent intracranial haemorrhage)
Prophylaxis for surgery
CP bypass
What is the problem with needing FFP rapidly?
Takes 30 minutes to thaw
Why might you give FFP?
Massive haemorrhage
DIC with bleeding
Prophylaxis
What FFP ABO type can you give to everyone?
AB+
How do you get cryoprecipitate?
Allowing FFP to thaw and skimming off the precipitate that forms on top
What is cryoprecipitate used for?
Source of fibrinogen and factor 8
What is now implemented when giving blood samples to the blood bank?
Second sample
What is the difference between group and save and cross match?
Group and save = full ABO, Rh and alloantibody testing
Crossmatching - mixing blood together from different samples (need straight away)
How is cross matching done nowadays?
Automatically
What is direct coombs test used for?
Autoimmune haemolytic anaemia
Passive Anti-D
Haemolytic transfusion reactions
What is indirect coombs test used for?
Cross matching
What is involved in a direct coombs test?
Mix patient’s erythrocyte with anti-human globulin and examine for agglutination
What is involved in indirect coombs test?
Mix patient’s serum with donor erythrocytes and anti-human globulin
+ve –> evidence of pre-existing Ig in patients circulation
How many blood group systems are there?
> 21
What are some of the less relevant blood groups?
Kell Duffy S, s, U P Kidd
Don’t need to know these as such, just be aware that there is sometimes a funny Ab in the patient’s system
If you need red cells in minutes what blood do you take?
O-
NB may have alloantibodies but these won’t be lifethreatening reactions
If you need red cells urgently what blood do you take?
Type specific ABO, RhD
If you need red cells non-urgently what blood do you take?
Full cross match
What is involved in massive haemorrhage protocol?
Rapid control of bleeding (e.g. obstetric intervention, surgery, interventional radiology)
Immediate supply of 6 units RCs, 4 units FFP 1 units platelets
Phone up 22 22
What are the top risks with transfusion?
Fever
TACO
What are the risks of viral transmission/fatal haemolysis with blood transfusion?
Very low
What are most transfusion related deaths due to?
TACO - transfusion associated circulatory overload
How can TACO be avoided?
Only write up units 1 at a time
Assess cardio risk factors
What steps have been taken to reduce prion transmission?
Leucodepletion
UK plasma not used for fractionation
Imported FFP
What is TRALI?
Transfusion related acute lung injury
Ab in the donor blood –> activation of granulocytes
Symptoms: dyspnoea, hypotonia, fever, chest infiltrates, hypotension etc.
What has caused a decrease in rates of TRALI?
FFP all from males now
If the patient is looking ill after transfusion what should you consider?
TACO, AHTR, bacterial infection, TRALI, FNHTR
What is FNHTR?
Febrile non-haemolytic transfusion reaction - fever unknown
How do you treat FNHTR?
Anti-pyretic
If mild - keep transfusing, if severe stop and send back to bank
If patients have urticaria after transfusion what may this be indicative of?
Anaphylaxis or mild allergic reaction
What should you give patients if they present with urticaria after transfusion?
antihistamine
If becomes more severe consider adrenaline, salbutamol, IV fluids
What might dyspnoea indicate after a transfusion?
TACO or TRALI or anaphylaxis
How should you manage TACO?
Oxygen, diuretic, ventilation, reduce transfusion rate, adrenaline
How should you manage TRALI?
Stop and contact blood bank
What are your differentials if a patient presents in shock after transfusion?
IBCT, anaphylaxis, TRALI, TAS
How should you treat shock in patient after transfusion?
Adrenaline, hydrocortisone, antihistamines IV fluid/ITU admission Ventilation Antibiotics FFP/Platelets if DIC
What tends to cause haemolytic disease of the new born?
RhD tends to be the main one
Others like c, K may also do it
What is the presentation of HDNB?
+DAT at birth, anaemia, jaundice
How can you prevent HDNB?
Prophylactic anti-D at time of birth, 28 weeks and after any sensitising event (e.g. trauma)
If HDNB develops how can you monitor it?
Ab titres
Doppler US of fetus carotid artery
How can you manage HDNB?
IU infusions via cannulation of umbilical artery
Give babies phototherapy and transfusion when born
How does neonatal alloimmune thrombocytopenia present?
Intracranial haemorrhage
What is leucopheresis?
Bone marrow harvests/lymphocyte infusions
What other banks exist?
Breast milk, bone, tendons, heart valves, faecal transplant
Islet cells, mesenchymal cells
How can GvHDx be prevented?
Irradiation of blood
What is acute haemolytic transfusion reaction?
ABO incompatibility –> severe destruction of donor RBCs by recipient Abs
