Blood Transfusions

Question 1

Describe fresh whole blood.

Answer 1

Used soon after collection (<6hrs)
Contains physiological concentrations of RBCs, some functional platelets, proteins and coagulation factors
Stored at room temp.

Question 2

Describe stored whole blood.

Answer 2

> 8hrs since collection
No functional platelets, loss of labile clotting factors
Stored at 2-6 degrees C for max. 21 days

Question 3

Describe packed RBCs.

Answer 3

Separated from plasma by centrifugation
PCV is higher than of whole blood - usually 70-80%
Stored for max. 42 days

Question 4

Describe fresh frozen plasma.

Answer 4

Stored at -18 degrees C for max. 1yr
Contains all coagulation factors
Contains physiological concentrations of albumin and other plasma proteins

Question 5

Describe frozen plasma.

Answer 5

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

Question 6

Describe cryoprecipitate.

Answer 6

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

Question 7

Which patients may benefit from transfusion therapy?

Answer 7

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?

Question 8

How do we decide whether to give an anaemic patient a transfusion?

Answer 8

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!

Question 9

What are the clinical signs of a transfusion reaction?

Answer 9

Fever, tachycardia, dyspnoea, muscle tremors, vomiting, weakness, collapse, haemoglobinaemia/uria

Question 10

What blood types exist in dogs?

Answer 10

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

Question 11

What blood type should we give canine patients?

Answer 11

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)

Question 12

What occurs after a patient has received its first blood transfusion?

Answer 12

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

Question 13

What blood types exist in cats?

Answer 13

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)

Question 14

What blood type should we give feline patients?

Answer 14

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

Question 15

What is cross matching?

Answer 15

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

Question 16

When should we perform cross matching?

Answer 16

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

Question 17

How can we obtain blood products needed?

Answer 17

Pet blood banks - canine only

Local collection from donors - for cats

Question 18

How do we choose a good donor?

Answer 18

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)

Question 19

What is the donation process like?

Answer 19

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

Question 20

What are the volume limits for blood donation?

Answer 20

Dogs = 15ml/kg
Cats = 10-12ml/kg

Question 21

Describe open vs closed donation.

Answer 21

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

Question 22

How do we administer blood products?

Answer 22

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

Question 23

What should we NOT do during a blood transfusion?

Answer 23

Do not feed the patient

Do not administer drugs/fluids other than 0.9% saline through the same catheter

Question 24

What consideration should we have after a patient has received a transfusion?

Answer 24

Ensure all future/present healthcare providers are notified that patient has received a transfusion

Question 25

What should we monitor prior to, every 15-20mins during and 1, 12 and 24hrs after a transfusion?

Answer 25

Attitude/mentation
Rectal temperature
Pulse rate and quality
Respiratory rate and character
MM colour and CRT
Plasma and urine colour

Question 26

When should we check PCV and TS in transfusion patients?

Answer 26

Prior to, upon completion and 12-24hrs following transfusion

Question 27

What are some examples of immunologic transfusion reactions?

Answer 27

Antigen-antibody sensitivity reactions (IgG and IgM mediated)
Cytokines from product storage/leukocytes within product
Allergic/hypersensitivity reactions (IgE mediated)

Question 28

What are some examples of non-immunologic transfusion reactions?

Answer 28

Volume overload
Citrate intoxication
Coagulopathy/thrombosis
Ammonia intoxication
Bacterial contamination of the unit
Pre-transfusion haemolysis

Question 29

What are the basic principles for managing a transfusion reaction?

Answer 29

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