Transfusion medicine

How to know if patient needs a blood transfusion?

• signs suggestive of reduced oxygen provision to tissues

  • tachycardia

  • tachypnoea

  • lethargy

  • weakness

• ensure patients are normovolaemic before deciding whether to transfuse

• looking in 10-15% range for cats, and 15-20% for dogs

What blood products to use?

• replace like with like

• blood loss - replace with whole blood or packed red cells

• haemolysis - replace with packed red cells

• coagulopathy - replace with fresh frozen plasma, regular plasma, or cryoprecipitate

What is the UK pet blood bank?

• provide all blood products as well as equipment required and guidance on administration

• can deliver 24/7 - central depot in Leicester

• provide crossmatch service with IDEXX

• no feline blood

What blood type to use?

• ideally give type-matched blood to dogs

• if unable to blood type the dog, administer DEA 1 negative

• NEED to give type-matched blood to cats

What do we need to remember about giving blood types to dogs?

• dogs don’t have naturally occuring antibodies - develop antibodies following exposure (transfusion) - may have acute haemolytic reaction

• if a DEA 1 negative dog receives DEA 1 positive blood - very mild, delayed reaction

• If a DEA 1 positive dog receives DEA 1 negative blood - doesn’t demonstrate any signs

What do we need to remember about giving blood types to cats?

• type A is dominant to B, and AB is polygenic

• cats have naturally occuring auto antibodies

• imperitive to give type matched blood to cats as can have fatal acute haemolytic reactions from incompatible blood

• Giving type B cats type A blood - severe acute haemolytic reaction

• Giving type A cats type B blood - milder, delayed reaction

How to blood type the patient?

• send to external laboratory for confirmation - sometimes not time to do so

• use a card or cassette based method

  • available for DEA 1 and A/B

• rule out agglutination before using card-based method

What to do if auto-agglutination is occuring?

• need to wash patient red cells before using card based method

• cassette method is preferred

What is crossmatching?

• detects more haematological incompatibilities than typing

• blood typing only detects DEA 1 and A/B - cross matching detects majority of antibody-antigen incompatibilities

• won’t detect non-antibody mediated incompatabilities

What is a major cross match?

recipient antibodies against donor red cells

What is a minor crossmatch?

donor antibodies against recipient red cells

When do you need to crossmatch the patient?

• if they have had a previous transfusion cross matching is necessary

  • unless within 3-5 days of first transfusion

• if received plasma products recently or with previous pregnancies - it is a grey area on whether its needed or not

How to crossmatch a patient?

• lab method is gold standard - straightforward but time consuming

• IDEXX and Pet Blood Bank will crossmatch and deliver bags to you

• In-house gel-based methods are inaccurate - not recommended

• rarely get 100% compatible donor - choose least risky

How much to give to the patient?

• a restrictive transfusion target (PCV 21-25%) is likely just as good as liberal transfusion (PCV 35-45%)

• formulas serve a rough guide

• round up to nearest bag

• wide variation in post transfusion PCV

What are the general considerations on how to administer blood product?

• intravenous administration (intra-osseous also acceptable)

• all products administered at a slow rate initially - to avoid transfusion reaction

• consider equipment available and ability to monitor the patient

• maintaining sterility is vital as blood is an excellent growth medium for bacteria

• give through transfusion set with an in-line filter

What is the best method of transfusion for dogs?

administer drip-by-drip through transfusion set

What is the best method for transfusion in cats?

administer via syringe driver

How fast should you give the transfusion?

• 0.5-1 ml/kg/hr for first 15-30 mins

• increase to 4-6 ml/kg/hr after

• can be given as fast as possible in emergencies

What should you flush the IV with and why?

• flush with 0.9% NaCl

• because calcium containing fluids can form clots

Should you warm the blood?

• warming is not recommended

  • can be warmed to room temp

Should we give patient access to food and water?

• give access to water

• no access to food as can make patient feel sick

What should you monitor?

• monitor for signs of transfusion reaction (during and after admin)

• monitor HR, RR and rectal temp

• check for signs of anaphylaxis - swelling, urticaria, nausea, vomiting

• try and categorise to decide on underlying cause and treatment

What is an acute haemolytic reaction?

• reaction within minutes

• severe - can be fatal —> stop transfusion

What do we see with an acute haemolytic reaction?

• tachycardia / tachypnoea

• nausea / vomiting / pyrexia

• haemolysed serum

• haemoglobinuria

What is a delayed haemolytic reaction?

• reaction may take days

• milder reaction

What do we see with a delayed haemolytic reaction?

• slow removal of red blood cells

• mild antibody reaction or new antibody formation

• jaundice / bilirubinaemia

• slow reduction in PCV

What are the types of respiratory transfusion reactions?

• TRALI

• TACO

What happens with TRALI resp transfusion reactions?

• immune reaction

• inflammation of vessels in lung

What happens with TACO resp transfusion reactions?

• volume overload

• happens in cats / small dogs / animals with cardiac or renal disease

What may we see with a respiratory transfusion reaction?

• panting

• stress

• pain

• pyrexia

• thrombosis

What do we do if we suspect respiratory TRALI or TACO?

• stop transfusion

• oxygen support

• radiographs

• furosemide - can be used for TACO

• be careful when giving fluids as can make signs worse

What are the possible non-haemolytic transfusion reactions?

• pyrexia / anaphylaxis

• citrate toxicity

• sepsis

What are the signs of pyrexia / anaphylaxis due to non-haemolytic transfusion reaction?

• vomiting / nausea

• panting / pyrexia / tachycardia

What do we do if patient has pyrexia / anaphylaxis due to non-haemolytic transfusion reaction?

• pause transfusion

• slower rate

• administer chlorphenamine and maropitant

What are the signs of citrate toxicity due to non-haemolytic transfusion reaction?

• shaking / shivering

What do we do if patient has citrate toxicity due to non-haemolytic transfusion reaction?

• check iCa2+

• administer calcium

• separate line

What to do if in doubt of transfusion reaction