transfusion medicine

What determines if patient needs blood transfusion

CS of reduced oxygen provision to tissues (tachycardia, tachypnoea, lethargy, weakness)

If normovolaemic

What % range for deciding transfusion - cats

10-15%

What % range for deciding transfusion - Dogs

15-20%

What to use in blood loss to replace

Whole blood, packed red cells (+fluid therapy)

What to use in haemolysis to replace

Packed red cells

What to use in coagulopathy to replace

Fresh frozen plasma (poisoning), regular plasma, cryoprecipitate (vWD)

Contents of blood products - whole blood

55-65% plasma

35-45% red cells

Contents of blood products - Packed red cells

20-40% Plasma

60-80% red cells

Contents of blood products - Fresh frozen plasma (frozen within 6hrs collection)

99.9% plasma

Clotting factors (I-XII), vWF

Contents of blood products - Frozen plasma (frozen >6hrs since collection)

99.9% plasma

Clotting factors (II, VII, IX, X)

How long can most practices store whole blood

<21d

Where to get canine blood products from + advice + equipment + IDEXX cross matching service

UK pet blood bank (Leicestershire)

What blood type to give if can’t determine patient dog’s (cats must have correct type)

DEA 1 negative

Plasma blood type to give

DEA 1 negative

Which blood types can be given to DEA 1 + dogs without reaction (no naturally occurring ab to RBC)

DEA1+, DEA1-

Why does giving DEA 1 - dog DEA 1 + blood produce delayed reaction

No naturally occurring ab (occur from exposure)

Acute haemolytic reaction in subsequent transfusion

Blood type system in dogs

Dog erythrocyte antigen system (DEA)

Blood type system in cats

A/B system

A dominant to B

AB = polygenic

Why is it so important to give type matched blood to cats

Naturally occurring auto antibodies

Fatal acute haemolytic reactions from >1ml incompatible blood

Cat breeds more likely to have type B blood (can’t be given type A blood or severe acute haemolytic reaction)

Devon Rex, British blue

What happens if you give B cats type A blood

BAD - severe acute haemolytic reaction

Strong antibodies

What happens if you give A cats type B blood

Not As Bad - milder delayed haemolytic reaction

Weaker antibodies

How to blood type patients (DEA, A/B)

External lab (long)

Cassette (using control lines+ positive lines)/ lateral flow tests

Card based method (need to rule out auto agglutination e.g. IMHA → wash patient RBC)

Purpose of cross matching

Detect more haematological incompatibilities (ab-ag, haemolysis) than blood typing (DEA1, A/B only)

Doesn’t detect non ab mediated compatibilities

Types of cross matching

Major - recipient ab against donor red cells

Minor - donor ab against recipient red cells

When to cross match

Previous transfusions (unless within 3-5d (not enough time for ab))

Received plasma products

Previous pregnancies

How to cross match (rarely 100% compatible)

External lab (days)

IDEXX + pet blood bank (24hr)

In house gel methods (inaccurate)

Transfusion targets (PCV) - usually give full bags/units

Restrictive = PCV 21-25%, better bone marrow response

Liberal = PCV 35-45%

How to give blood products

IV, intra osseous

Initial Slow rate (dose dependent transfusion reactions)

Sterility

Monitor

Transfusion set with in-line filter

Equipment in giving blood products

Transfusion set with in-line line filter (210 microm, remove debris+clots)

Dogs - drip by drip with transfusion set

Cats - syringe driver

Speed of giving transfusion (inc after 30min)

0.5-1ml/kg/hr (15-30min)

Inc to 4-6ml/kg/hr

Emergency = fast as possible

Within 4hrs

How to flush IV transfusion sets as Ca interferes with anticoagulant + leads to clots

0.9% NaCl (normal saline)

Patient safety during transfusion

Meds in separate line

Don’t actively warm blood- breakdown RBC

Water access

No food access

Don’t disconnect (sterility)

How to monitor patient (what to monitor)

HR, RR, rectal temp, signs of anaphylaxis (swelling, urticaria/ hives, nausea, V)

Types of transfusion reactions

Haemolytic, respiratory, non haemolytic

Types of haemolytic transfusion reactions - CS, what to do

Acute (mins)- tachycardia, tachypnoea, nausea, V, pyrexia, haemoglobinuria → check with haemolysed serum (reddish tinge) → stop transfusion

Delayed (days) - mild ab reaction → jaundice, bilirubinaemia, slow dec in PCV

Types of Respiratory transfusion reactions- CS, what to do

Panting, stress, pain, pyrexia, thrombosis

TRALI (transfusion related acute lung injury) - immune reactions

Taco (transfusion associated circulatory overload)- vol overload in cardiac/ renal disease

Stop transfusion, oxygen support, radiographs

Types of non haemolytic transfusion reactions - CS + what to do

Pyrexia/ anaphylaxis - V, nausea, panting, pyrexia, tachycardia → pause/slow transfusion, chlorphenamine, maropitant

Citrate toxicity - shaking, lower Ca conc in blood → check iCa2+, administer Ca

Sepsis

What to do if concerned about transfusion reaction

15-30min break, restart at slower rate, dont disconnect patient, symptomatic treatment

Common vol blood to give

10-20ml/kg

Most common canine blood type

DEA 1 negative