Blood transfusion Flashcards
What are blood group due to?
Antigens on the surface of the red blood cells
What do ABO genes encode?
Glycosyltransferase
What are glycans added to?
Protein or lipid on the red blood cell
What do the A and B genes code for?
Transferase enzyme
What is the A antigen?
N-acetyl-galactosamine
What is the B antigen?
Galactose
What is the difference between A and B and O?
‘O’ gene is non-functional allele (doesn’t put anything on the red cell)
How are A and B classed as?
Dominant
What is O classed as?
Recessive
What do people with blood group A have antibodies against?
Blood group B
What do people with blood group B have antibodies against?
Blood group A
What do people with blood group O have antibodies against?
Blood groups A and B
Do blood group AB have antibodies?
No
Which antibody is responsible for immune tolerance?
IgM
If a patient is blood group A. what donor blood can the receive?
A and O
If a patient is blood group B. what donor blood can the receive?
B and O
If a patient is blood group AB. what donor blood can the receive?
A, B and O
Universal recipient
If a patient is blood group O. what donor blood can the receive?
O
If a patient is blood group A. what donor plasma can the receive?
A
If a patient is blood group B. what donor plasma can the receive?
B
If a patient is blood group AB. what donor plasma can the receive?
AB
If a patient is blood group O, what donor plasma can the receive?
O
What needs to be checked and recorded before someone can donate blood?
- Extensive ‘behavioural’ screening
- Sex, age, travel, tattoos
- Tested for ABO and Rh blood groups
- Screened for HepB/C/E, HIV, syphilis
- Variably screened for: HTLV1, malaria, West Nile virus, Zika virus…
What are possible indications for a blood transfusion?
To correct severe acute anaemia, which might otherwise cause organ damage
To improve quality of life in patient with otherwise uncorrectable anaemia
To prepare a patient for surgery or speed up recovery
To reverse damage caused by patient’s own red cells - Sickle Cell Disease
What is blood separated into?
Plasma
Buffy coat
Red blood cells
What does plasma contain?
- Clotting or coagulation factors
- Albumin
- Antibodies
What does the buffy coat contain?
- Platelets
* White cells/ leucocytes
How is compatible blood chosen?
- Blood sample (EDTA tube)
- Two sample policy
- Group and Screen/Save
- Cross matching
How many samples of blood need to be taken before giving blood to a patient?
2 sample (policy)
What does group and screen include?
- ABO and RhD type
- Checked against historical records
- Screen for allo-antibodies in serum
What is Coombs test used for?
Trying to detect antibodies on the surface of blood cell
What will happen if there is a reaction between antigens on the red blood cells an it is an IgM reaction?
Blood cells will clump together
What will happen if there is a reaction between antigens on the red blood cells an it is an IgG reaction?
The blood cells wont clump together
What is direct combs test used for?
Checks if the immune system is destroying the red blood cells as there aren’t enough of them
What does indirect coombs test check?
to make sure donated blood is compatible with the patients
What are some examples of what direct coombs testing looks for?
- autoimmune haemolytic anaemia
- passive anti-D
- haemolytic transfusion reactions
What are some examples of what indirect coombs testing looks for?
Cross matching
How is the transfusion of blood cells carried out?
- Stored in a fridge at 4oC
- Transfuse over 2-4 hours
- 1 unit increments hemoglobin by about ~5 g/L
Platelets
1 dose platelets is the equivalent 4 blood donations(=4 pooled or 1 apheresis donor)
Increases platelet count by about 30.109/L
Stored at ~22oC
Short shelf life- 7 days
Transfuse over 20-30 minutes
What are the uses of platelet transfusion?
Massive haemorrhage- Keep platelet count above 75x109/l
Bone marrow failure- keep platelet count <10-15 × 109/litre, or <20 × 109/litre if additional risk, e.g. sepsis
Prophylaxis for surgery
• Minor procedures- keep platelet count 50x109/l;
• More major surgery keep platelet count 80x109/l; CNS or eye surgery 100x109/l
Cardiopulmonary bypass- use only if bleeding
Plasma
1 unit from 1 unit of blood
Stored frozen, allow 30 minutes to thaw
What are possible uses of plasma transfusion
- Massive haemorrhage
- DIC with bleeding
- Prophylaxis
What is Cryoprecipitate?
- Made from gradually thawing FFP
* It is a fibrinogen concentrate
