Transfusion Flashcards
What criteria must patients meet in order to be allowed to given blood?
Healthy donors req’d
=> Hb level 135 for men and 125 for women
=> Minimum weight 50kg
To avoid donors becoming anaemic after giving blood
How is blood processed centrally before being used for transfusion?
- centrifuged to separate into component parts
(red cells, FFP and platelets) - These then undergo HIV/Hep/syphilis testing
How long do red cells, FFP and platelets last for?
- Red cells for 35 days in fridge
- FFP for 2-3 years in freezer
- platelets for 7 days at room temp
What other blood products are available from the transfusion lab?
- Anti-D
- Prothrombin complex concentrate (help pts clot)
- IV Immunoglobulin
- human albumin
What is meant by the ABO blood grouping system?
- Genes on chromosome 9 code for transferases
- These modify ‘H substance’ on red cell membrane
What are the most common blood groups in the UK?
O and A
What antigens and antibodies are found on Blood group A?
A antigen and Anti-B antibodies
What antigens and antibodies are found in blood group B?
B antigens and Anti-A antibodies
What antigens and antibodies are found in blood group AB?
A and B antigens, no antibodies
What antigens and antibodies are found in blood group O?
no antigens and anti-A and anti-B antibodies
Blood group O has an autosomal recessive inheritance pattern. TRUE/FALSE?
TRUE
A and B are dominant over O
=> must be OO alleles to have blood group O
What is the difference between RhD positive and negative?
RhD+ has D antigens on RBCs and NO D antibodies
RhD- has no D antigens but Anti-D antibodies
What blood group can be given to any patient, regardless of their blood group?
O negative
What percentage of the UK population are RhD positive?
85%
Is RhD negative an autosomal dominant or recessive trait?
Recessive
RhD+ is dominant
=> pt must be “dd” to be RhD negative
Can RhD cause a transfusion reaction?
Yes
- can cause reaction and haemolytic disease of foetus and newborn
=> RhD negative patients should only be given RhD negative blood
When may antigens/ antibodies other than the ABO and Rhesus systems cause transfusion reactions?
If patient exposed to new antigen (e.g. through pregnancy or previous transfusion) then repeat exposure may result in transfusion reaction
How are patients ABO grouped before transfusion of blood?
- Identify antigens present on red cell using Antisera
OR identify antibodies with Reagent red cells
Agglutination will tell you what blood group is
=> can also be done with other antibody types to prevent an unknown transfusion reaction
What is meant by crossmatching blood to check it is suitable for transfusion?
- check if donor cells are incompatible with patient plasma.
- If NO agglutination- cells can be issued for transfusion.
What are the main indications for a blood transfusion?
- Symptomatic anaemia Hb<70g/L
- Major bleeding
remember to consider transfusion alternative
How many units of blood should be transfused before reassessing a patient?
single unit of red cells, then reassess patient
Why would a patient need a platelet transfusion?
- Prophylaxis in bone marrow failure/ Treatment of bleeding in thrombocytopenic patient
- Prophylaxis prior to surgery/ procedure in thrombocytopenic patient
Why would patients need a fresh frozen plasma transfusion?
- Treatment of bleeding in patient with coagulopathy (PT ratio >1.5)
- Prophylaxis prior to surgery
- Tx of haemorrhage or trauma
How should patients be monitored during transfusion?
Before blood is commenced
Obs at 15 mins then 60 mins after completion
