Transfusion Medicine continues Flashcards
Feline blood type is based on what system?
AB system
A = dominant to B
AB polygenic
Most cats = type A
What to rememebr about cats and blood transfusions
Imperative to type-match cats as can have fatal acute haemolytic reactions from as little as 1ml of incompatible blood due to presence of naturally occurring auto-antibodies against diff blood types
Give a Type B cat type A blood =
BAD = severe acute haemolytic reaction
Give type A cat type B blood =
Not AS BAD = milder delayed reaction
Blood typing vs cross mathching
Blood typing = find out whether DEA 1 +ve or -ve or A,B or AB (cat) using cassette (preferred) or card
Cross match = detects the majority of antibody-antigen incompatibilities as animals have more than just DEA 1 or AB on RBC
How do you blood type a patient?
Gold standard is sending to an external laboratory for confirmation –rarely time to do so!
Otherwise using a card or cassette based method
Only available for DEA 1 and A/B
Imperative to rule out auto agglutination before using card based method
Less important for cassette based method
Cassette preferred (looks like lateral flow
What is cross matching?
Detects more haematological (Type II HS) incompatibilities than typing
Blood typing will only detect DEA 1 and A/B, whereas crossmatching will detect the majority of antibody-antigen incompatibilities
Will not detect non-antibody mediated incompatibilities
What is a major cross match?
Recipient has antibodies against donor red cells = DO NOT GIVE as will have haemolytic reaction
What is a minor cross match?
Donor antibodies against recipient (patient) red cells can still give blood as the amount of Ab in minor cross match aren’t high. Recipient doesn’t have much blood anyway
Ideally want no reaction at all but can still give transfusion if minor cross match
When do you NEED to cross match as opposed to blood type a patient?
If has had previous transfusion (blood) then it is imperative more than 3-5 days
NOT if
within the first 3-5 days after previous transfusion
Grey area with need for cross match if have received plasma products previously
Similarly unclear with previous pregnancies
Normal PCV in dogs =
35-50%
How much transfusion shoudl you give?
A ‘restrictive’ transfusion target (PCV 21-25%) is probably just as good as, if not better, than a ‘liberal’ transfusion (PCV 35-45%)
Reason as less likely to volume overload patient
Use formulas as a rough guide
In reality round up to the nearest bag/cat
Blood is a scarce resource
Out of fridge more than 6 hrs must be disposed
How much should you administer?
Transfusion reactions generally dose dependent so all products administered at a slow rate initially to assess for any reactions, building up thereafter (0.25 ml/kg a min and then inc)
What to remember about IV blood transfusion
What is another method of transfusion?
Maintaining sterility is vital as blood is an excellent growth medium for bacteria – do not disconnect IV
Intra-osseous
More about transfusion admin
Must be given through a transfusion set with an in-line filter (210um)
In dogs, better to administer drip-by-drip through a transfusion set rather than through a fluid pump
Theoretically drip by drip
Pump can damage RBC but human medicine reckons pumps are safe
In cats, better to administer via a syringe driver as normally only 20-40 ml
However, important to use the method that is safest for the situation/practice
