Blood groups and transfusion medicine Flashcards
1
Q
What are blood groups determined by?
A
- antigens present on the surface of erythrocytes
2
Q
What are the 2 types of antibody to blood group antigens
A
- naturally occurring alloantibodies
- acquired
3
Q
What are the feline blood groups?
A
- A
- B
- AB
- Mik recently identified
4
Q
What are the pre-formed naturally occurring antibodies against non-self feline blood antigens?
A
- Type A carry weak anti-type B antibodies
- Type B carry very strong anti-type A antibodies
- Type AB carry no antibodies against type A or B antigens
5
Q
Prevalence of the different feline blood groups
A
- as a rule type B is considered less common
- UK data reported ~2/3 DSH were type A
- some pedigree cats are almost invariably type A (Siamese and derivative breeds_
- some pedigree cats have high incidence of type B (BSH, rex’s and rag dolls)
6
Q
Why do you need to blood type every donor and recipient cat before transfusions (even in an emergency)
A
- type A cats will all have antibodies against type B antigens
- severe reactions or transfusion failure
7
Q
What happens if you give type A blood to type B cat?
A
- severe acute haemolytic reaction (intravascular haemolysis of type A blood)
- within seconds of receiving transfusion
- may be fatal
8
Q
What happens if you give type B blood to type A cat?
A
- extravascular haemolysis (milder CS)
- low 1/2 life of RBCs, PCV will fall to pre-transfusion levels within days
9
Q
Feline blood type compatibility
A
- A + A = compatible
- B + B = compatible
- AB + AB = compatible
10
Q
Feline neonatal isoerythrolysis - cause
A
- Type A or AB kittens born from a type B queen
- RBCs in the kittens are targeted by “anti-A” antibodies from the queen (which are present naturally in type B cats from approx. 3mo)
– These transfer from colostrum while <24h old
11
Q
Feline neonatal isoerythrolysis - CS
A
- ‘Fading’ kittens
– red/brown urine
– jaundice
– anaemia
– sudden death
– varies from subclinical to severe
12
Q
Feline neonatal isoerythrolysis - prevention
A
- Breeders should be urged to type queen (and the tom if queen found to be type B)
13
Q
Canine blood groups - DEA
A
- 1
- 3
- 4
- 5
- 6
- 7
- 8
14
Q
Which canine blood antigen has the most transfusion significance?
A
- DEA 1 -> it is highly antigenic
15
Q
What canine blood type is the only one with a commercial test kit that is widely available?
A
- DEA 1
16
Q
What blood type are dogs described as?
A
- DEA 1 positive (~70%) or DEA 1 negative (~30%)
17
Q
Do dogs have pre-formed antibodies against non-self canine blood types?
A
- no
18
Q
Blood typing in dogs
A
- where possible should always blood type and give matched blood
– +ve -> +ve
– -ve -> ive - in an emergency can give an untyped transfusion but this is not recommended
– in this case DEA -ve should be used as this can be given to +ve or -ve dogs
19
Q
Canine blood type compatibility
A
DEA 1 +ve blood should only be administered to a DEA 1 +ve patient
- This will prevent sensitising a DEA 1 -ve dog to the DEA 1 antigen
- Also reduce chance of delayed haemolytic reaction
Subsequent administration of DEA 1 +ve to a sensitised DEA –ve dog can produce acute haemolytic transfusion reaction
- Potentially fatal
No adverse effects if administer DEA –ve to DEA +ve but not good use of –ve blood
- ~30% dog population –ve
- Risk depleting stocks of –ve so that unavailable if –ve patient
requires transfusion
20
Q
Cross-matching
A
- in vitro test that looks for potential reactions between a donor’s and pts blood
- these show as agglutination or haemolysis
- major cross match assesses compatibility between donor RBCs and pt plasma/serum
- minor cross match assesses compatibility between donor plasma/serum and pt RBCs
21
Q
Options for cross-matching
A
- manually in-house if required
- rapid Vet-H in-house gel cross-match kit
- submit to commercial lab
22
Q
Why cross match? When is it required?
A
- additional blood groups that can’t be tested in-house
– dogs can have many blood types that coexists (Dal, DEA 4)
– cats likely to have additional blood types recognised (e.g. Mik) - cats have naturally occurring antibodies, therefore cross-matching recommended prior to any transfusion
– often just done on subsequent - dogs:
– if recipient has been previously transfused >4d prior
– hx of previous transfusion reaction
– transfusion hx unknown - will need to be repeated with each subsequent transfusion (if >4d in between)
23
Q
Incompatibility - what to do in urgent cases
A
- may need to transfuse despite incompatibility
- can call Pet Blood Bank / Lab personnel in these circumstances for advice
- generally transfuse the least incompatible
– advice should be sought and signed statement from supervising vet
24
Q
What is a transfusion?
A
- intravenous therapy with whole blood or blood products
25
What is the aim of a transfusion?
- replace the missing component of blood and in the case of conditions such as anaemia and haemorrhage, to increase the oxygen carrying capacity
26
Imminent indications for a blood transfusion
- evidence for circulatory collapse means transfusion is essential
- rapid drop in PCV to <30% in dogs or <15% in cats
- absolute PCV of 15-20% -> depends a lot on historical and presenting CS
- if PCV <10-12%, automatic trigger as organ hypoxia is imminent, particularly myocardium
- signs of specific organ hypoxia, particularly CNS
- clear evidence for reduced oxygen carrying capacity
-- tachycardia, tachypnoea, bounding peripheral pulse (water-hammer -> rapid rise and fall of pulse)
- concern that PCV is likely to fall lower over period of time whereby transfusion would be difficult to organise
27
How much does a single unit of whole blood contain?
~450ml of blood
28
Fresh (FWB) vs stored (SWB)
Fresh (FWB)
- Transfused within 8 hours of collection
- Contains all components of blood
- Only product available currently in UK that
provides any level of PLTs
Stored (SWB)
- Refrigerated (<4C) and not transfused within 8 hours of collection
- lasts 3 weeks
- Lacks PLTs, WBCs and labile clotting factors (FV, FVIII and vWF)
29
Indications for use of whole blood (generally FWB)
- acute blood loss
- active bleeding
30
Blood products
- PRBCs
- Plasma
-- fresh frozen plasma (FFP)
-- frozen plasma (FP)
- cryoprecipitate
- cryosupernatant
31
PRBCs
= packed red blood cells
- suspended in nutrient solution (SAG-M) stored in fridge (4C ± 2C)
- lasts for 42d
32
Plasma
- stored at -18C
- if processed and frozen within 24h of collection = fresh frozen plasma (FFP)
-- shelf life 1y
-- contains labile and non-labile clotting factors
- if frozen >24h after collection or FFP after 1 year = frozen plasma (FP)
-- shelf life additional 4y
-- contains non-labile clotting factors
33
Indications for PRBCs
- any pt developing CS of low tissue oxygenation due to anaemia
34
Indications for FFP
- main purpose is for coagulopathies
-- contains all the clotting factors
34
Indications for FP
- for non-labile clotting factor needs as toxicities causing coagulopathies, haemophilia B
35
Cryoprecipitate
- shelf life 1y
- plasma fraction separated from fresh frozen plasma
-- controlled thawing and centrifugation
- concentrated product labile clotting factors (fibrinogen, factor VIII, Von Willebrands factor)
36
Indications for cryoprecipitate
- pre-treatment for vWD deficiency
37
Cryosupernatant
- shelf life 1y
- remaining fraction after cryo-precipitate has been produced
- contains plasma proteins including albumin and vitamin K dependent clotting factors II, VII, IX, and X
38
Indications for cryosupernatant
- for non-labile clotting factor needs as toxicities causing coagulopathies, haemophilia B
39
Transfusion considerations
- some products contain more than you need - risks?
- some may contain less - risks?
- costs? whole blood from donor generally cheaper - but what if multiple transfusions required?
- benefits of transfusion MUST outweigh the drawbacks
40
What to transfuse
- Fresh blood gives: RBCs, albumin, platelets, FII, VII, IX, X, FVIII, vWF, AT III, other proteins
- Stored whole blood gives: RBCs, albumin
- Packed RBCs give: RBCs, +/- albumin
- Fresh frozen plasma gives: albumin, FII, VII, IX, X, FVIII, vWF, AT III, other proteins
- Frozen plasma gives: albumin, FII, VII, IX, X, AT IIII, +/- other proteins
- Cryosupernatant gives: albumin, FII, VIII, IX, X, AT III, other proteins +/- FVIII, vWF
- Cryoprecipitate gives: FVIII, vWF
41
Benefits of autologous transfusion
- reducing potential for exposure to allogenic blood
- reduces risk of (new) infectious dz
- reduces chance of transfusion reactions
- immediate availability
42
Donor criteria (dog)
- fit & healthy
- 1-8y/o
- >25kg
- good temperament
- never travelled abroad
- vaccinated
- not on any meds
43
Pre canine blood collection
- full physical health check
- haematology & biochemistry (minimum PCV/TS)
- blood tying
44
Equipment required for canine blood collection
- 450ml blood collection bag with CPD/CPD-A
- electronic weigh scales
- macoclamp-P
- tube stripper
45
Canine blood collection - step by step
- 2 assistants to hold dog
- lateral recumbency on table
- venipuncture în jugular vein (generally right jugular)
- release clamp and blood should flow to bag easily
- regularly rock the collection bag to mix with anticoagulant
- 480g (450ml)
- clamp line
- remove needle and apply neck bandage
- use the tube stripper to strip the blood I the line into the bag
- check demeanour, HR, mm quality & pulse quality
- offer small amount of food and water
46
Donor criteria (cat)
- healthy
- 1-8y/o
- >4kg lean BW
- preferably indoor cat
47
Pre feline blood collection
- perform full physical exam (consider cardiac US)
- full haematology & biochemistry (PCV/TS as minimum)
- FeLV/FIV if outdoor cat
- blood type
48
Equipment required for feline blood collection
- 60ml lure tip syringe
- 3 way tap
- source of CPDA-1/CPD
- macoclamp P
- or small animal syringe collection set
- sedation/anaesthesia generally required
-- ketamine midazolam combo
49
Feline blood collection - step by step
- calculate amount of blood to be drawn (11-13ml/kg)
- add required amount of CPD/CPDA-1 to the 60ml syringe
- lateral/dorsal recumbency
- assistant raises vein
- perform jugular venipuncture and lightly pull on 60ml syringe
- blood should flow freely (carefully rock frequently during the draw to ensure mixing with anticoagulant)
- when at desired amount, remove needle, apply pressure to neck for 2 minutes with saw then apply neck bandage
- monitor HR< mm
- administer isotonic fluids after?
50
Equipment required to administer a blood product
- unit to be administered
- zip lock bag
- tray/bowl to use as water bath (warm product to 37C)
- thermometer
- filtered giving set (or in case of cats/smaller dogs - Hemo-Nate filter)
- IV catheter (largest gauge possible for the pt)
51
Administration of blood products containing red cells - volume to transfuse
= (target PCV - recipient PCV) / donor PCV x kg x N
N = 90 for dogs
N = 60 for cats
52
Estimation for donor PCV for whole blood dogs & cats
- Donor PCV = whole blood dog ~45%(unless measured), packed red cells ~62% (unless measured)
- Donor PCV = whole blood cat ~37%(unless measured)
53
Administration of blood products containing red cells - how to evaluate the amount of red cells needed
A few calculations have been suggested
- 2ml transfused whole blood /kg recipient weight raises PCV by 1%
- 1ml transfused packed red blood cells /kg recipient weight raises recipient PCV by 1%
54
Administration of blood products containing red cells - infusion rate for stable pts
- initial infusion rate of 0.5-1.0ml/kg/hr
-- 15-30mins
-- monitor for evidence of transfusion reaction
- if no reaction, can be increased to 4-6ml/kg/hr
- in an emergency (e.g. severe acute haemorrhage), red cells can be given as fast as necessary
- transfusion to a stable end point of 25-30% PCV suggested
- the unit should be delivered within 4h of beginning the transfusion
55
Administration of plasma products - dose & infusion rate
- total dose necessary will depend on reason
- generally starting dose 20ml/kg is recommended
- initial infusion rate 0.5-1ml/kg/hr
- if no signs of reaction, can be increased to 4-6ml/kg/hr
- the unit should be delivered within 4h of beginning the transfusion
56
Administration of transfusion - steps
- blood products need to be prepared carefully (once breached have limited lifespan)
- warm to 37C
- consent must be obtained
- should be given IV (peripheral or central)
-- intraosseous can be used in moribund pts
- all components should be administered via filtered giving set
- monitor pt closely throughout and post
-- TPR, resp effort, CRT, mm colour q5m for 1st 30m, then monitor q15-30m
- transfusions shouldn't be administered through the same IV line as any solutions containing Ca or glucose
- it's recommended that red cell products are transfused by gravity alone to both dogs and cats
- plasma transfusions can be administered via infusion pump or syringe drive
-- advisable to check accuracy with manufacturer
57
What is a transfusion reaction?
- any undesired side effect noted as a consequence of a blood product transfusion
- can be classified based on
-- timing (acute vs delayed)
- pathophysiological mechanism (immunological vs non-immunological reactions)
58
Transfusion reactions - clinically will commonly present as
- increase in temp
- change in resp/heart rate
- change in mm colour
- visible oedema
- GI signs
- more severe signs also possible
59
Immunological vs non- immunological reactions
Immunological
- haemolytic
- non-haemolytic
Non-immunologic reactions
- not mediated through immune mechanisms
- circulatory overload
- bacterial contamination
- hypothermia
- citrate toxicity
- dilution coagulopathy
- hyperammoniaemia and acidosis
- disease transmission
60
Acute haemolytic immunological transfusion reaction
- what it is
- examples
- clinical signs
- what to do
- blood type incompatibility
- class II (antigen-antibody) HS reaction -> acute intravascular haemolysis
- uncommon (particularly in dogs & horses)
- type B cat administered type A or AB blood
- DEA 1 -ve dogs sensitised to DEA 1 and repeated exposure
- CS may include: fever, tachycardia, dyspnoea, muscle tremors, V+, weakness, collapse, haemoglobinaemia, haemoglobinuria, shock, death
- transfusion should be stopped immediately
- give IV fluids +/- corticosteroids
61
Delayed haemolytic immunological transfusion reaction
- what it is
- examples
- clinical signs
- what to do
- extravascular haemolysis
- 3-21d post transfusion
- may occur in dogs administered incompatible blood on 1st transfusion
- reduced lifespan of donated erythrocytes (post-transfusion PCV rapidly declines)
- hyperbilirubinaemia +/- bilirubinuria
- specific tx generally not required
62
Febrile non-haemolytic transfusion reaction
- what it is
- examples
- clinical signs
- what to do
- acute PLT/WBC hypersensitivity
- most common transfusion reaction with whole blood
- mild and transiet fever
- leukoreduction can help minimise this
63
How to avoid a transfusion reaction
- blood typing
- cross matching
- appropriate donor screening
- correct collection, preparation, storage and administration of products
63
Acute hypersensitivity transfusion reaction
- what it is
- examples
- clinical signs
- what to do
- anaphylactic (allergic type I HS)
- IgE antibodies which activate mast cells
- minor skin reactions such as pruritus and urticaria to more severe such as hypotensive shock
- stop the transfusion
-- for milder reactions: antihistamines + corticosteroids
-- severe signs: intensive shock therapy
64
Therapeutic plan for a transfusion reaction
- if suspect transfusion reaction: STOP transfusion immediately
- CE
-- cardioresp system
-- temperature
-- haemoglobinaemia or haemoglobinuria
- supportive tx as indicated e.g. fluids, corticosteroids, oxygen, antihistamines, adrenaline, diuretics
- check blood typing or cross-matching
- check blood bag for evidence of lysis
