Blood Transfusions Flashcards
Describe fresh whole blood.
Used soon after collection (<6hrs)
Contains physiological concentrations of RBCs, some functional platelets, proteins and coagulation factors
Stored at room temp.
Describe stored whole blood.
> 8hrs since collection
No functional platelets, loss of labile clotting factors
Stored at 2-6 degrees C for max. 21 days
Describe packed RBCs.
Separated from plasma by centrifugation
PCV is higher than of whole blood - usually 70-80%
Stored for max. 42 days
Describe fresh frozen plasma.
Stored at -18 degrees C for max. 1yr
Contains all coagulation factors
Contains physiological concentrations of albumin and other plasma proteins
Describe frozen plasma.
Frozen plasma = fresh frozen plasma that is >1yr old or has been thawed and re-frozen
Stable coagulation factors will remain
Labile factors will be lost, e.g. VIII and von Willebrand factors
Stored at -18 degrees C for up to 5yrs
Describe cryoprecipitate.
Made by slowly and partially thawing fresh frozen plasma which is then centrifuged again
Cryoprecipitate = the precipitate collected from this second centrifugation
Rich in labile clotting factors, e.g. fibrinogen, VIII and vWF
Which patients may benefit from transfusion therapy?
Those with disease that result in a deficiency of a blood constituent e.g.
Hypovolaemic anaemia e.g. blood loss
Euvolaemic anaemia e.g. immune-mediated haemolytic anaemia
Coagulopathies e.g. rodenticide toxicity
Thrombocytopenia and thrombopathia?
Hypoalbuminaemia?
How do we decide whether to give an anaemic patient a transfusion?
Blood products are indicated if there are clinical signs of anaemia (weakness, tachycardia, tachypnoea, indirect measures of poor oxygen delivery e.g. high blood lactate)
Decision is not based on patient’s PCV value alone!
What are the clinical signs of a transfusion reaction?
Fever, tachycardia, dyspnoea, muscle tremors, vomiting, weakness, collapse, haemoglobinaemia/uria
What blood types exist in dogs?
DEA 1, 3, 4, 5 and 7 / Dal
DEA 1 is most antigenic and the only DEA we can type for in practice
Dogs possess no naturally occurring antibodies against DEA 1
Most dogs are Dal positive, Dalmatians are Dal negative
What blood type should we give canine patients?
DEA 1 negative dogs should only receive DEA 1 negative blood
DEA 1 positive dogs can receive either DEA 1 positive or negative blood
In an emergency, DEA 1 negative blood can be given to an untyped patient
As do not possess naturally occurring alloantibodies, first transfusion can be un-typed (not recommended)
What occurs after a patient has received its first blood transfusion?
If DEA 1 negative dog exposed to DEA 1 positive blood, will develop anti-DEA 1 antibodies over the next few days (if exposed again, will have a transfusion reaction)
Subsequent transfusions can lead to reaction due to sensitisation to remaining DEAs or other RBC antigens - cross matching required
What blood types exist in cats?
A, B and AB / others e.g. Mik
In cats, naturally occurring antibodies are present in the plasma
Type A = low numbers of weak anti-B alloantibodies
Type B = lots of anti-A antibodies
Type AB = no antibodies (rare, so often given type A as is less antigenic)
What blood type should we give feline patients?
Ideally given blood that matches their blood type
When AB blood not available for AB patient, type A is the next best choice
As transfusion mismatches can be fatal, all donors and recipients will need to be typed, even in an emergency
Subsequent transfusions can lead to reactions due to sensitisation against RBC antigens outside AB blood group system - cross matching required
What is cross matching?
Used to determine serological compatibility
Major crossmatch = the recipient’s serum and the donor’s RBCs
Minor crossmatch = the donor’s serum and the recipient’s RBCs
When should we perform cross matching?
The recipient has received a transfusion > 4 days ago
There has been a history of a transfusion reaction
The recipient’s transfusion history is unknown
The recipient has previously been pregnant
Ideally all feline transfusions
Dalmatians
How can we obtain blood products needed?
Pet blood banks - canine only
Local collection from donors - for cats
How do we choose a good donor?
Healthy and generally 1-8yrs of age
No history of travel
Receiving routine preventative health care
Never received a transfusion
Good jugular veins
Canine = large (<25kg), well-tempered, clear disease screens
Feline = large (>4kg), BCS 4-6/9, blood typed, clear disease screens (ideally indoor cats)
What is the donation process like?
Clinical history and full physical exam
Blood sampling for PCV/TS +/- haem/biochem, typing and infectious disease screening
Cats need sedation and catheter placed for subsequent IVFT
Clip hair from area over both jugular veins and apply EMLA
Should be performed aseptically
Use anti-coagulant (CPDA) at correct ratio
Following donation, cats should receive IVFT replacement
Food and water can be offered (cats = once recovered from sedation)
Activity should be restricted for 24hrs
What are the volume limits for blood donation?
Dogs = 15ml/kg Cats = 10-12ml/kg
Describe open vs closed donation.
Open = one or more additional sites of potential bacterial contamination
Closed = only exposure is when needle is uncapped to perform venepuncture, only suitable for large dogs, shelf life is longer for blood collected
Both systems require anti-coagulant
How do we administer blood products?
Visually inspect bag, gently thaw frozen products e.g. FFP/FP
Record baseline patient parameters and monitor throughout
Administer IV using blood giving set/IVFT giving set with an in-line filter
Give approx. 10-20ml/kg
Start admin slowly (1ml/kg/hr) for 20 mins to allow early recognition of transfusion reactions
Give the rest over 4-6hrs
What should we NOT do during a blood transfusion?
Do not feed the patient
Do not administer drugs/fluids other than 0.9% saline through the same catheter
What consideration should we have after a patient has received a transfusion?
Ensure all future/present healthcare providers are notified that patient has received a transfusion
What should we monitor prior to, every 15-20mins during and 1, 12 and 24hrs after a transfusion?
Attitude/mentation Rectal temperature Pulse rate and quality Respiratory rate and character MM colour and CRT Plasma and urine colour
When should we check PCV and TS in transfusion patients?
Prior to, upon completion and 12-24hrs following transfusion
What are some examples of immunologic transfusion reactions?
Antigen-antibody sensitivity reactions (IgG and IgM mediated)
Cytokines from product storage/leukocytes within product
Allergic/hypersensitivity reactions (IgE mediated)
What are some examples of non-immunologic transfusion reactions?
Volume overload Citrate intoxication Coagulopathy/thrombosis Ammonia intoxication Bacterial contamination of the unit Pre-transfusion haemolysis
What are the basic principles for managing a transfusion reaction?
STOP the transfusion
Distributive shock? - fluid resuscitation
Hypersensitivity reaction? - antihistamines
Bacterial contamination? - send sample for microbiology and treat with broad spectrum IV antibiotics
Dyspnoea? - provide oxygen
Check patient/product for evidence of haemolysis
Intravascular haemolysis? - monitor renal function
Volume overload? - slow infusion rates, diuretic therapy
