Transfusion medicine Flashcards
How can you assess if a patient needs a blood transfusion?
- Based on clinical signs
- Signs suggestive of reduced oxygen perfusion to tissues
What are some clinical signs of reduced oxygen perfusion to tissues?
Tachycardia
Tachypnoea
Lethargy
Weakness
Before a blood transfusion what needs to be assessed in terms of a patients circulating volume?
Need to be normovolaemic
Before transfusing following acute haemorrhage what needs to be considered?
Following acute haemorrhage, there is a lag-period (~24h) before a decrease in PCV is seen so the PCV of an acutely bleeding dog may not reflect its true oxygen carrying capacity
Which blood product should be used in:
- blood loss
- haemolysis
- coagulopathy
- Replace with whole blood
- Replace with packed red cells
- Replace with fresh frozen plasma, regular plasma, or cryoprecipitate depending on the cause
How do the components of the following differ:
- whole blood
- packed red cells
- fresh frozen plasma
- 60% plasma, 40% red cells
- 20% plasma, 80% red cells
- 99.9% plasma (clotting factors + VWF)
UK pet blood bank
- after 6 hours post collection there is no longer any … left in the blood product
Platelets
Describe how fresh frozen plasma is acquired, used and stored
- Centrifuge whole blood within 6-8 hours of donation
- It contains most clotting factors (including vWF) and thus can be used in the majority of coagulopathies
- Has a shelf like of 1 year when frozen
Describe how frozen/regular plasma is acquired, used and stored
- either plasma that has been acquired >6-8 hours after donation or fresh frozen plasma that is greater that has been stored for more than one year
- it contains the majority of clotting factors although has reduced numbers of the labile clotting factors (V + VIII)
- it does have the vitamin K dependent clotting factors (II, VII, IX, X) thus can be used in brodifacoum rodenticide toxicity
- has a shelf life of 5 years
If you do not know a dogs blood type which should be administered?
DEA 1 -ve
If you do not know a cats blood type which should be administered
Imperative to give type-matched blood to cats prior to transfusion
Which hypersensitivity reaction is involved in blood transfusions?
Type II
- antibodies against the antigens on red cell surface membranes
Following a blood transfusion what will occur if your recipient has antibodies against the antigen on the donor RBCs?
There will be a haemolytic reaction – RBCs will be removed By the monocytic macrophage reaction of the spleen
Which blood canine blood type is the universal donor and why?
DEA 1-ve
- contain no antigens on their surface
What happens if a sensitised DEA 1-ve dogs receives DEA 1+ve blood?
If the sensitised recipient receives further red blood cells with the same antigen 3-5 days after the previous transfusion, then an acute haemolytic reaction occurs as the recipient already has auto-antibodies present.
What does DEA stand for?
Dog erythrocyte antigen
What will be the reaction of a DEA 1 +ve dog receive DEA 1-ve blood?
Will not demonstrated any signs and will not become sensitised
What will be the reaction of a DEA 1 –ve dog receiving DEA 1 +ve blood?
Will have a very mild, delayed reaction but will subsequently become sensitised
Which dog breed usually has DEA 1-ve blood and makes good donors?
Greyhounds
Describe the blood typing system in cats
Based on the A/B system with A being dominant to B and AB being polygenic – most cats are type A
Why is it imperative to blood type match cats?
They can have a fatal acute haemolytic reaction due to the presence of naturally occurring auto-antibodies
Giving type B cats type A blood is?
BAD – severe acute haemolytic reaction
Giving type A cats type B blood is?
not As Bad – milder, delayed reaction
How can you blood type a patient?
- Card or cassette based method
- A line at both the DEA 1 and Control line = DEA 1 +ve
- A line at just the control line = DEA 1 -ve
What is cross matching?
- Detects more haematological (Type II HS) incompatibilities than typing
- Blood typing will only detect DEA 1 and A/B, whereas cross matching will detect the majority of antibody-antigen incompatibilities
Describe a major cross match
Recipient antibodies against donor red cells - haemolytic reaction, dont give blood
Describe a minor cross match
Donor antibodies against recipient red cells - can still give blood
When is it imperative to cross match a patient?
If they have had a previous transfusion
- unless within the first 3-5 days after previous transfusion
- the only way you can do it without cross matching is if you give it blood from the same donor
How should you cross match a patient?
- Laboratory method is gold standard
- Straightforward but time-consuming manually
- In-house gel based methods are inaccurate and not recommended
How should a blood transfusion be administered?
- Intra venous
- Intra-osseous also acceptable (into bone marrow)
- All products administered at a slow rate initially, building up thereafter
- Maintaining sterility is vital as blood is an excellent growth medium for bacteria
How fast should a transfusion be delivered?
- 0.5-1ml/kg/hr for first 15-30 mins
- Increasing to 4-6ml/kg/hr thereafter
- Can be given as fast as possible in an emergency situation
Why can an IV only be flushed with saline?
Calcium containing fluids can form clots
When giving a transfusion what needs to be monitored in the patient?
- signs of transfusion reactions during and after administration
- HR, RR, temperature
- signs of anaphylaxis such as swelling, urticaria, nausea, vomiting
