Blood Transfusions Flashcards
Why do we transfuse blood?
- mainly because of bleeding
- but also because of failure of production
Describe the inheritance of blood groups.
A and B are co-dominant whilst O is recessive
What does blood group B have antibodies against?
A
What does blood group A have antibodies against?
B
What does blood group O have antibodies against?
A and B
What does blood group AB have antibodies against?
No antibodies
Who is universal red cell donor?
Blood group O negative
Who is the universal red cell recipient?
Blood group AB positive
Who is the universal FFP donor?
Blood group AB positive
Who is the universal FFP recipient?
Blood group O negative
What can happen to RhD negative individuals during pregnancy or transfusion?
- They can make anti-D if exposed to RhD cells
- This can lead to transfusion reactions or haemolytic disease of the new-born
What screening do blood donors undergo?
- Extensive ‘behavioural’ screening
- Sex, age, travel, tattoo
- 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 the components and products of blood?
- Plasma
- Clotting or coagulation factors
- Albumin
- Antibodies
- Buffy Coat
- Platelets
- White cells
- Red Blood Cells
What are some indications for RBC transfusion?
- Severe acute anaemia
- Uncorrectable anaemia
- Prepare patient for surgery or speed up recovery
- Sickle cell disease
How are RBCs stored and transfused?
- Stored at 4oC
- Transfuse over 2-4 hours
- 1 unit increments ~5 g/L
How are platelets stored and transfused?
- 1 dose platelets (=4 pooled or 1 apheresis donor)
- Increments 20-40 x 10^9/L
- Stored at ~22oC, shelf life 7 days
- Transfuse over 20-30 minutes
What are the components of plasma?
- Fresh frozen plasma
- Cryoprecipitate
What are the indications for FFP?
- Massive haemorrhage
- DIC with bleeding
- Prophylactic
How is FFP used?
- 1 unit from 1 unit of blood
- Stored frozen, allow 30 minutes to thaw
What are the lab tests for FFP?
PT and APTT
What is the lab test for cryoprecipitate?
Fibrinogen
How is cryoprecipitate stored?
Frozen, allow 20 minutes to thaw
How are patients grouped and screened?
- ABO and RhD type
- Checked against historical records
- Screen for allo-antibodies in serum
What is the direct Coombs test used for?
- Autoimmune haemolytic anaemia
- Passive anti-D
- Haemolytic transfusion reactions
What is the indirect Coombs test used for?
Cross matching
At what temperature do the ABO and Rh blood group systems usually react?
37C
What blood is usually available within minutes?
O- red cells (AB plasma)
What bloods take time and are non-urgent?
- Full cross match to select the correct ABO/RhD type
- If allo-antibodies choose antigen negative blood
Once a massive haemorrhage protocol has been activated what is there an immediate supply of?
- 6 units red cells
- 4 units FFP
- 1 unit platelets
What should decision to transfuse be based on?
The decision to transfuse should be based on a careful assessment of patient’s clinical state and must be justified as essential to prevent major morbidity or mortality.
How is prion disease transmittable?
By blood transfusion from early in the disease
How should transfusion reactions be managed?
- Stop transfusion
- Check patient identity against component label
- Consider: anaphylaxis, circulatory overload (TACO), acute haemolytic transfusion reaction (AHTR), bacterial infection, lung injury (TRALI)
What is sensitisation in rhesus disease?
Development of maternal anti D antibodies
Does IgG cross the placenta?
Yes
How does haemolytic disease of the new-born present at birth?
- Positive direct antiglobulin test
- Jaundice
- Anaemia
How is HDN prevented?
Using prophylactic anti-D at 28/40 weeks or during sensitising events
What is the treatment for HDN?
- Careful monitoring
- Antibody titres
- Doppler ultrasound
- Intrauterine transfusions
