Blood Transfusion

Question 1

What indications are there for blood transfusion?

Answer 1

Hypovolaemic anaemia (e.g. blood loss).
Euvolaemic anaemia (e.g. IMHA).
Coagulopathies e.g. rodenticide toxicity.
Thrombocytopenia and thrombopathia?
Hypoalbuminaemia?

? – In practice, platelets may not survive the process.

Question 2

1. When are blood products indicated for anaemic patients?
2. What other measurements could be an indicator but not a solo indicator?

Answer 2

1. When there are clinical signs of anaemia.
   – Weakness.
   – Tachycardia.
   – Tachypnoea.
   – Indirect measures of poor oxygen delivery e.g. high blood lactate.
2. PCV value.

Question 3

Blood products available in the UK for dogs.

Answer 3

Whole blood.
Packed red blood cells (PRBCs).
Fresh frozen plasma and frozen plasma.
Cryoprecipitate and cryoprecipitate poor plasma.

Question 4

Blood products available for cats in the UK.

Answer 4

Whole blood (more so locally).
– Feline blood banks currently in their infancy.
– Whole blood obtained from consenting clients, friends, family, colleagues.
– Obtained from local donor colonies.
– Obtained from donors from the animal blood register.

Question 5

Processing of blood to make blood products.

Answer 5

Collect whole blood.
– Hard spin this blood to get packed red blood cells (PRBCs) and fresh frozen plasma.
–> Fresh frozen plasma either slowly and partially thawed and centrifuged to get cryoprecipitate and cryoprecipitate poor plasma.
–> or 1 year old fresh frozen plasma or fresh frozen plasma that is thawed and then re-frozen is called frozen plasma.
– Light spin this blood to get packed red blood cells (PRBCs) and platelet rich plasma.
–> Platelet rich plasma further processed to produce fresh frozen plasma and platelet concentrate.

Question 6

Fresh whole blood.

Answer 6

Used soon after collection (<6 hours).
Contains physiological concentrations of red blood cell, SOME functional platelets, proteins and coagulation factors.

Question 7

Stored whole blood.

Answer 7

Used >8 hours after collection.
No functional platelets, loss of labile clotting factors (V, VIII, vWF)

Question 8

Packed Red Blood Cells (PRBCs).

Answer 8

Separated from plasma by centrifugation (hard spin).
PCV higher than of whole blood – usually 70-80%.

Question 9

Fresh Frozen Plasma (FFP).

Answer 9

Stored at -20 to -40 degrees C, <1 year.
Contains ALL coagulation factors.
Contains physiological levels of albumin and other plasma proteins.
No RBCs.

Question 10

Frozen plasma (FP).

Answer 10

FFP that is >1 year older OR that has thawed and been re-frozen.
Stable coagulation factors will remain.
Labile factors will be lost (e.g. V, VIII, vWF).
Stored at <-18 degrees C for up to 5 years.
Still contains physiological levels of albumin.

Question 11

Cryoprecipitate (cryo).

Answer 11

Made by slowly and partially thawing fresh frozen plasma which is then centrifuged again.
Cryoprecipitate is the precipitate collected from this second centrifugation.
Rich in fibrinogen, VIII, vWf.

Question 12

Principle of deciding what your specific patient needs.

Answer 12

Replacing like with like. Use the product that most closely replaces what is missing.

Question 13

Why do we use specific products for specific patients?

Answer 13

To use blood products efficiently.
To save more lives with a single unit of blood.
To reduce the risk of the patient developing transfusion reactions and complications.

Question 14

1. What is the ideal product for blood loss anaemia? – what other products could be appropriate?
2. What product can be used for thrombocytopenia/pathia?
3. What is the ideal product for unknown coagulopathy? – what may also be appropriate to use?
4. What is the ideal product for rodenticide toxicity? – what may also be used?
5. What is the ideal product for von Willerbrand Disease / haemophilia A. – What else may be used?
6. What would be the ideal blood product for IMHA?

Answer 14

1. Fresh whole blood. – Stored whole blood, packed red blood cells.
2. Fresh whole blood.
3. Fresh frozen plasma – Fresh whole blood.
4. Frozen plasma. – Fresh frozen plasma.
5. Cryoprecipitate – FFP, FWB.
6. PRBCs.

Question 15

What other consideration must be made when selecting a blood product?
– why?

Answer 15

Blood type. – RBCs possess antigens on their surface and the plasma may contain antibodies.
If given a transfusion with the wrong blood type, antibodies may react with the antigens in the donated blood = transfusion reaction.

Question 16

Transfusion reaction symptoms.

Answer 16

Fever
Tachycardia
Dyspnoea
Muscle tremors
Vomiting
Weakness
Collapse
Haemoglobinemia
Haemoglobinuria

Question 17

Blood types in dogs.

Answer 17

Dog erythrocyte antigen.
Labs can type for 6 of them: 1, 3, 4, 5, 7.
A dog can be positive or negative for each of these.
DEA 1 is most antigenic (most likely to cause transfusion reactions with mismatches) and the only DEA that we can type for in clinical practice.
Dogs possess NO naturally occurring ‘pre-formed’ antibodies against DEA 1.

Question 18

Dal.

Answer 18

Most dogs Dal positive.
Most Dalmations Dal negative.
Cannot type dogs for Dal in house.
Meaning if we wanted to give a dalmation a blood transfusion, the blood would need to come from another dalmation OR they will need to be cross-matched.
Many blood types but they are not clinically relevant.

Question 19

Rules in blood transfusion blood types and administration.

Answer 19

DEA 1 negative dog should only receive DEA 1 negative blood.
DEA 1 positive dog can receive DEA 1 positive or negative blood.
Technically, the first transfusion can be given untyped as dogs do not possess naturally occurring alloantibodies (but delayed reactions can still be seen).
In emergency, DEA 1 negative blood can be given to an untyped recipient.
DON’T FORGET TO COLLECT A BLOOD SAMPLE PRIOR TO EMERGENCY TRANSFUSION!

Question 20

What happens if a DEA 1 negative dig is given DEA 1 positive blood?

Answer 20

Develops anti-DEA 1 antibodies over the course of a few days.
Then if exposed to DEA 1 positive blood for a second time, will have a transfusion reaction.

Question 21

What can still occur regardless of blood typing and appropriate transfusion with subsequent transfusions? – what is required in these cases?

Answer 21

Subsequent transfusions can still lead to reactions due to sensitisations to the remaining 4 DEAs or other RBC antigens.
– Cross matching.

Question 22

1. Blood types in cats.
2. What blood type are most Siamese cats?
3. What blood type are most ragdolls?

Answer 22

1. Cats have 3 blood types: A, B, AB.
   Naturally occurring / pre-formed alloantibodies are present in the plasma.
   – Antibody formation does not require prior exposure through transfusion or pregnancy.
   Antibodies may cause fatal transfusion reactions upon first transfusion and are also responsible for neonatal isoerythrolysis.
   Other types exist that we cannot routinely type for e.g. Mik.
2. A.
3. AB.

Question 23

1. Blood formation in terms of antigens and antibodies in type A cats.
2. Blood formation in terms of antigens and antibodies in type B cats.
3. Blood formation in terms of antigens and antibodies in type AB cats.

Answer 23

1. Type A surface antigens on RBCs and pre-formed anti-B antibodies in the plasma, which are weak and low in number.
2. Type B surface antigens on RBCs and lots of pre-formed anti-A antibodies in the plasma.
3. Both type A and type B surface antigens on RBCs and NO antibodies against either antigen in their plasma.

Question 24

1. Ideal for type transfusion in cats?
2. What can be given to a type AB cat if there is no AB blood available?
3. In emergency?

Answer 24

1. To give blood that matches their blood type.
2. Type A.
3. Need to type all donors and recipients even in emergency as transfusion mismatches can be fatal.

Question 25

1. What happens if a type A cat is exposed to type B blood? 2. What can occur regardless of blood typing and appropriate transfusion with subsequent transfusions? -- what is required in these cases?

Answer 25

1. Naturally occurring 'alloantibodies' will trigger severe transfusion reaction. This does not require and history of prior exposure or 'sensitisation'. 2. Can still lead to reaction due to sensitisation against RBC antigens outside the A-B blood group system. -- Cross matching.

Question 26

1. What is the purpose of cross matching? 2. What is a major crossmatch? -- why is it referred to as the major crossmatch? 3. What is a minor crossmatch? 4. In testing, what is a sign that it is not a compatible match?

Answer 26

1. To determine the serological compatibility between recipient and donor. 2. Mix the recipient's serum and donor's red blood cells. -- Most likely to cause severe transfusion reactions. 3. Mix the donor's serum and the recipient's red blood cells. 4. Agglutination or haemolysis.

Question 27

When is it appropriate to perform cross matching?

Answer 27

- The recipient had received a transfusion > 4 days ago. - There has been a history of a transfusion. - The recipient's transfusion history is unknown. - Ideally all feline transfusions. - Dalmations.

Question 28

How can blood for transfusion be obtained?

Answer 28

From pet blood banks or practices enrolled in their share schemes. -- Collection and processing can be specialised. -- Blood banks / share schemes will often be able to provide equipment needed for transfusion. Local blood collection.

Question 29

Requirements for all donors.

Answer 29

Should be healthy and generally between 1-8 years of age. No history of travel. Should be receiving routine preventative health care. Should have never received a transfusion. Should have good jugular veins.

Question 30

1. Requirements for canine donors. 2. Requirements for feline donors.

Answer 30

1. Large (>25kg). Well tempered. 'Clear' disease screens. 2. Large (>5kg). BCS 4-6. Must be blood typed. Should have 'clear' disease screens -- FeLV, FIV, mycoplasma haemofelis. Ideally indoor only (difficult).

Question 31

Open vs closed donation.

Answer 31

Open: One or more additional sites of potential bacterial contamination. Closed: Only exposure of blood to environment = when needle uncapped to perform venepuncture. Only suitable for large dogs. Shelf life longer for blood collected using a closed system. Both require anti-coagulants.

Question 32

Donation process (collection).

Answer 32

- Clinical history and full physical examination to confirm good health. - Blood sampling for PCV/TS +/- haematology, biochemistry, typing and infectious disease screening. - Cats generally need sedation and catheter placed for subsequent IVFT. - Clip hair from area over both jugular veins and apply EMLA. - Aseptically. - Use anti-coagulant (CPDA) at correct ratio. - Volume limits of 15ml/kg for dogs and 10-12ml/kg for cats. - Following donation, cats should receive IVFT replacement. - Food and water can be offered (cats -- once recovered from sedation). - Activity should be restricted for 24 hours.

Question 33

Monitoring frequencies of recipient.

Answer 33

1. Prior to transfusion. Every 15-30mins during transfusion. 1 hour after transfusion. 12 hours after transfusion. 24 hours after transfusion.

Question 34

What should be monitored in the recipient?

Answer 34

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

Question 35

In terms of blood, what should be checked and when?

Answer 35

PCV/TS should be checked prior to transfusion, on completion of transfusion and 12 to 24 hours following transfusion.

Question 36

Antigen-antibody sensitivity reaction (IgG and IgM mediated).

Answer 36

Haemolytic and causes fever. Can range from mild to severe. Fever, tachycardia, dyspnoea, muscle tremors, vomiting, weakness, collapse, signs of intravascular (haemoglobinaemia, haemoglobinuria) and extravascular (jaundice) haemolysis. Signs can be acute or delayed (weeks later -- although these are invariably mild).

Question 37

Allergic/hypersensitivity reaction (IgE mediated).

Answer 37

Not haemolytic and does not cause fever. Often mild. Pruritic, urticaria, erythema, angioedema, vomiting and dyspnoea (pulmonary oedema). Anaphylaxis is rare (i.e. distributive shock).

Question 38

Non-immunologic transfusion reactions.

Answer 38

Volume overload. Citrate intoxication. Bacterial contamination of the unit.

Question 39

Signs of volume overload. What patients are at greater risk?

Answer 39

Associated with pulmonary oedema (tachypnoea, dyspnoea, hypoxia etc.) Jugular distension/pulsations, chemosis (swelling of conjunctiva), serous ocular/nasal discharge, cavitary effusions. Does not cause fever. Patients with cardiac or renal disease more at risk.

Question 40

Signs of citrate intoxication. What patients are most likely to be affected.

Answer 40

Signs of hypocalcaemia (citrate binds to ionised calcium. Patients with liver disease more likely to be affected.

Question 41

Signs in the patient that they have reacted to bacterial contamination of the unit.

Answer 41

Fever, distributive shock, vomiting, diarrhoea, may have evidence of haemolysis.

Question 42

What to do in the face of a transfusion reaction.

Answer 42

- As student -- alert member of staff. - Stop the transfusion. - Signs of distributive shock? -- fluid resus. - Suspect hypersensitivity reaction? -- anti-histamines. - Suspect bacterial contamination -- send sample for microbiology and treat with broad spectrum IV ABX. - Dyspnoea? -- Provide O2. - Check the patient and the product for evidence of haemolysis. -- If intravascular, monitor renal function. - Signs of volume overload -- Slow infusion rates, diuretic therapy.