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LCB2 > Blood groups and transfusion medicine > Flashcards

Blood groups and transfusion medicine Flashcards

1
Q

What are blood groups based on?

A

Refer to inherited antigens on surface of the red blood cells

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2
Q

What does the degree of reaction to a transfusion depend on?

A
  • Titre (amounts) of antibodies
  • Isotype (IgM vs IgG)
  • Antibody leading to either immediate lysis or graudal removal
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3
Q

What is the effect of an antibody that leads to the immediate lysis of red blood cells regarding transfusions?

A

Totally failed transfusion, likely death

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4
Q

What determines the nature and frequency of blood transfusion reactions?

A

Presence of naturally occurring antibodies to blood group antigens

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5
Q

Compare the risk of transfusion reaction between dogs and cats, and explain

A
  • Dogs: few naturally occurring antibodies to major blood groups, low risk of transfusion reaction
  • Cats often have naturally occurring antibodies to major blood groups, increases risk of transfusion reaction
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6
Q

Name the main blood groups in dogs

A
  • > 10 blood group systems
  • Dog Erythrocyte antigen: 6 types: 1.1, 1.2, (1.3), 3, 4, 5, 7 (alternate: 1,3, 4, 5, 7)
  • Dal
  • Kai
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7
Q

Discuss the importance of the Dal and Kai blood groups

A
  • Usually delayed transfusion reactions

- Generally not typed for

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8
Q

Name the main blood groups of horses and identify the most immunogenic

A
  • 7 groups
  • A, C, D, K, P, Q, U
  • Aa, Qa, Ca
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9
Q

Why are standard breed horses commonly used as blood donors?

A

Low prevalence of Aa and Qa

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10
Q

Describe blood transfusions from cattle

A
  • Healthy donor, easy to handle, not heavily pregnant
  • Cross matching unnecessary, transfusion reactions after single administration of blood are rare and mild
  • Rare but consider in selected cases
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11
Q

Outline the principles of blood group testing

A
  • Blood typing detects antigen pattern on erythrocyte surface
  • Typing does not determine the presence of antibodies, i.e. does not mean totally compatible with donor
  • Simple kits available for cats, dogs, horses
  • Lab tests fo equine and bovine samples
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12
Q

Explain the principles of cross matching for blood transfusions

A
  • If have had previous transfusions will have antibodies to blood types so type is irrelevant
  • Assesses blood compatibility between donor and recipient
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13
Q

Compare a major and a minor cross match for blood transfusions

A
  • Major: detects if recipient’s serum contains any antibodies against the donor’s RBCs
  • Minor: detects if donor’s serum contains any antibodies against the recipient’s RBCs
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14
Q

Outline the method for cross matching of blood

A
  • Collect sampples from donor and recipient into anticoagulant tube (EDTA/heparin)
  • Centrifuse samples and remove and retain plasma
  • Resuspend in saline, repeat centrifuge-discard 3 times to wash RBCs
  • Prepare 3-5% washed RBC suspension with saline
  • Major: mix donor RBC suspension with plasma from recipient (equal vol) and vice versa for minor
  • Incubate at 37, 20 and 4°C
  • Check after 15-30 mins for haemolysis and/or agglutination by visual inspection or microscopically
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15
Q

What is the ideal blood donor type for dogs and why?

A

DEA1.1 negative, as antibodies to DEA1.1 are responsible for acute reactions in dogs, but less crucial vs cats

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16
Q

Outline the requirement for blood typing and cross matching in dogs for blood transfusions

A
  • Most dogs can receive first transfusion safely
  • Type first, ideally cross match
  • If cannot type, then transfusion should be fairly safe the first time
  • IF gone beyond 4 days, are likely to have mounted immune response to antigens the animal has encountered before so definitely need to blood type
  • Ideally second transfusion cross matched
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17
Q

What blood can be given to DEA 1.1 positive fogs?

A

Can receive DEA1.1 positive or negative

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18
Q

Outline the requirement for blood typing and cross matching in cats for blood transfusions

A
  • Much greater risk in cats than dogs of peracute and fatal transfusions reactions
  • Never transfuse without typing
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19
Q

Describe the reactions caused by type B feline blood type

A

Type B: high incidence of anti-A antibodies, leads to peracute reaction in A or AB cat

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20
Q

Which blood types can be given to which cats?

A
  • AB donate to A or AB, not B
  • AB can receive A or AB (low risk of anti-B antibodies in A may cause minor reaction)
  • Only B blood to B cats, not AB due to anti-A antibodies in type B cats
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21
Q

What are the aims of blood transfusions?

A
  • Replace what is lacking
  • Support patient whilst investigations are carried out/treatment initiated
  • Aim for clinical improvement rather than normal PCV (post transfusion PCV 25-30% in dogs, 20% in cats)
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22
Q

List the indications for the use of blood transfusions

A
  • Evidence for circulatory collapse
  • Rapid drop in PCV from normal to <20% in dogs, or <15% in cats (e.g. 10% or more)
  • Absolute PCV 15-20% depending on history and presenting clinical signs
  • If PCV < 10-12% immediate requirement
  • Signs of specific organ hypoxia, even if don’t look very anaemic, particularly CNS
  • Clear evidence of reduced oxygen carrying capacity e.g tachycardia/pnoea/bounding peripheral pulse
  • Concern that PCV is likely to fall lower over period of time where transfusion would be difficult to organise
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23
Q

Describe whole blood

A
  • “unaltered” blood from suitable donor
  • Should be harvested aseptically into closed collection system
  • Single unit = 450ml
  • Must be transferred within 8 hours or must be refrigerated after collection
  • All blood products are present and functioning
  • Most common agent transfused in private practices
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24
Q

What is whole blood most appropriate for?

A

Animals that have been haemorrhaging e.g. in coagulopathies, thrombocytopaenia, whole blood loss due to trauma/surgical complications

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25
Q

What are packed red blood cells most appropriate for?

A

Anaemia due to haemolysis/chronic disease/erythropoietic failure)
Can use in conjunction with colloidal solution if animal needs whole blood but not available

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26
Q

What is fresh frozen plasma most appropriate for?

A

Coagulopathies

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27
Q

What is contained in oxygen carrying solutions?

A

No cells, no plasma proteins

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28
Q

Describe stored whole blood

A
  • Fresh whole blood not transfused within 8 hours stored in fridge <4°C
  • Storage life of 3-5 weeks depending on anticoagulant used
  • Once transfusion begun must be complete in 4 hours
  • lacks platelets, WBCs, labile clotting factors
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29
Q

In which conditions is stored whole blood most valuable?

A

Haemorrahge due to trauma, vit K dependent rodenticide toxicity, coagulopathies due to liver disease

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30
Q

How are packed red cell products produced?

A
  • Prepared from whole blood by centrifugation
  • Whole blood collected into system, plasma separated
  • Red cells then resuspended in small volume of plasma and nutrient solution (e.g. SAG-M: sodium chloride, adenine, glucose, mannitol)
  • PCV 70-80%
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31
Q

Describe the storage of packed red cell products

A
  • Unit vol ~250ml
  • Shelf life 3-6 weeks depending on preservative (SAG-M 6 weeks)
  • Stored to enable air to circulate aroudn units
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32
Q

How are autologous transfusions carried out?

A
  • Taken from animal, through in-line filter and back into itself
  • Savenging systems available to harvest bnlood but not essential
  • cavity blood drawn into sterile sysringe and driven back into patient using in-line filter or placed asempically into sterile empty fluid bags
33
Q

What are the indications for use of autologous transfusion?

A
  • Acute cavity haemorrhage due to trauma/coagulopathies

- Harvest blood ready later for transfusion when anticipating haemorrhage

34
Q

What are the risks of autologous transfusions?

A
  • Sepsis

- Dissemination of neoplasia (do not perform in ruptured haemagiosarcomas)

35
Q

Outline the advantages of autologous transfusions

A
  • reduced potential for exposure to allogenic blood
  • Reduced risk of new infectious diseases
  • Reduces chance of transfusion reactions,
  • Immediate availability
  • No need to anticoagulate if present in body cavity >1hour
36
Q

How should autologous blood be transfused?

A

Using gravity feed rather - better survival of blood

37
Q

What is fresh frozen plasma?

A

Plasma harvested from fresh whole blood within 8 hours of collection, and provides maximal concentrations of all factors

38
Q

Describe the storage of fresh frozen plasma

A

If stored <20degreesC can be stored for up to 12 months

39
Q

Give the indications and dose of fresh frozen plasma

A
  • Acquired or inherited coagulopathies
  • DIC, pancreatitis
  • Liver disease
  • Perioperative use for vWD or other inherited coaguloapthies
  • Dose: 6-10mg/kg every 12 hours, up to 20 ml/kg for severe coagulopathy
40
Q

Desribe stored plasma/frozne plasma (non-FFP)

A
  • FFP >1 year old
  • OR FFP that has been thawed or separaed from whole blood >8 hours after collection (up to 24 horus acceptable to prepare plasma)
  • Some factor acitvity los but vit K dependent factors not labile so should be functional
  • Can use up to 5 years from preparation if stored
41
Q

What are the uses of stored plasma/frozen plasma?

A
  • Anticoagulant rodenticide toxicity, haemophilia B

- Liver disease, DIC, pancreatitis

42
Q

Describe oxyglobin

A
  • No longer available
  • cell free bovine polymerised ahemoglobin in LRS
  • Stored as deocyhaemoglobin
  • Binds oxygen less tightly than normal RBC-Hb, improved dissociation at lower tissue oxygen conc
  • Once opened, discard within 24 hours
  • Significant colloidal influence as well as oxygen carrying capacity
  • Impact and duration of effect is dose dependent
43
Q

What dose of oxyglobin will generate a PCV increase of:

a) 3% for 11-23hours
b) 12% for 74-82hours

A

a) 10ml/kg

b) 30ml/kg

44
Q

What dose and rate of oxyglobin should not be exceeded in the dog?

A
  • Dose not over 30ml/kg in 24 hour period

- Rate not exceeding 10ml/kg/hr

45
Q

What dose and rate of oxyglobin should not be exceeded in the cat?

A
  • Should not exceed 10ml/kg in 24 hour period

- Rate not exceeding 3ml/kg/hr

46
Q

When is the use of oxyglobin indicated?

A
  • Anaemia and circulatory collapse
  • Care with volume replete patients
  • Esp. good where rapid (temporary) oxygen provision is required
47
Q

How does oxyglobin affect clinical pathology parameters?

A
  • Due to heavy colour of product
  • Biochem and optical coagulation methods
  • Haematology less affected
  • Machines directly measuring Hb will also measure oxyglobin
48
Q

Briefly outline feline blood products

A
  • No bank for feline blood/blood products in UK
  • Problem of storage of feline blood is absence of true closed collection system
  • Whole blood obtained from practice based donor schemes currently
  • Human albumin used with some success in hypoalbuminaemic cats
49
Q

What volume of blood raises the PCV of the recipient by 1% in dogs and cats?

A
  • Dogs: donor PCV 45%, 2ml/kg raises by 1%

- cats: donor PCV 37%, 3ml/kg raises by 1%

50
Q

Give the formulae for the volume to be transfused in cats and dogs

A
  • Dogs: 1.5ml x desired PCV rise x BW in kg

- Cats: desired PCV rise (%) x BW in kg x2

51
Q

What are the risks of giving blood as a colloid and as a shock/replacement fluid?

A

Calcium chelation and hypocalcaemia, influencing clotting cascade and platelet function/activation

52
Q

Describe the standard rate of transfusion for dogs

A
  • Usually 0.25ml/kg/hr for 1-20 mins followed by 0.5mg/kg/hr for 10-20 mins
  • If no reaction, then increase rate to between 5-10ml/kg/hr to deliver blood within 4 hours
53
Q

Describe the standard rate of transfusion for dogs and cats

A

Usually 1-3ml/hg for first 10-20mins then if all ok increase to 5-10ml/kg/hr if circulation status appropriate

54
Q

What must not be co-adminsited with blood or blood products and why?

A

LRS - can lead to clotting or haemolysis

55
Q

Describe the method of transfusion

A
  • Often do not need to add supplemntary fluid when using packed red cells to reduce viscosity
  • Chlorpheiramine prior to starting transfusion suggested, but evidence of stopping acute reaction is lacking
  • Use cephalic, jugular or intraosseus
  • Filtered giving set
  • Infusion pumps give more reliable introduction of blood vs giving set
  • Main factor in preventing haemolysis is storage
  • Aim to complete within 4 hours to prevent contamination
  • Do not warm blood
56
Q

Compare the administration of blood transfusions to dogs and cats (and smaller dogs)

A
  • Dogs: standard blood unit infused via blood giving set which contains filter to remove clots and other large fragments
  • In cats/smaller dogs: syringe collection used, best administered by syringe driver and in-line pediatric filter
57
Q

Outline the monitoring of blood transfusions

A
  • TPR, resp effort, CRT, membrane colour every 5 mins for first half hour, during which rates change
  • Then reduce checks to every 15-30 mins until completion
  • Changes in parameters noted then reduce rate and review whether these continue to change
  • PCV should be obtained after an hour or so, ensures some vol distribution has occurred making PCV more accurate
58
Q

What is indicated if theimpact of a blood transfusion is lost within 24 hours?

A

Reaction or fulminable disease

59
Q

How can the risk of non-immunological reactions to blood transfusions be minimised?

A
  • Handle and store blood bags carefully
  • Always use filtered giving set for administration
  • Administer transfusions at an appropriate rate for the patient’s condition
  • Monitor recipient closely during first 30 min of transfusion
  • Consider initial slow flow rate (0.5mg/kg/kr during first 30 min of transfusion)
60
Q

Describe the signs of a transfusion reaction in a type B cat receiving type A blood

A
  • Massive intravascular haemolysis of type A donor blood
  • May occur after admin of very small vols of mismatched blood
  • Occurs rapidly
  • May be fatal
61
Q

Describe the signs of a transfusion reaction in a type A cat receiving type B blood

A
  • Extravascular haemolysis leading to milder clinical signs
  • Low half life of RBCs (2 days+)
  • PCV will fall to pre-transfusion levels within days of the transfusion
  • Can mimic ongoing haemolysis in cats with IMHA or haemorrhage
62
Q

What are the consequences of of acute haemolytic reactions due to pre-formed antibodies (IgG usually) directed against RBC?

A

Acute intravascular haemolysis: DIC and death possible

63
Q

Following a blood transfusion, what are the following signs indicative of?
Hyperthermia, tachycardia, dyspnoea, tremors, vomiting, collapse, haemoglobinuria

A

Acute intravascular haemolysis

64
Q

Which animals are more at risk of acute intravascular haemolysis following blood transfusions?

A

Cats more than dogs, increased risk in dogs with increasing no. of transfusions

65
Q

Compare the signs of acute intravascular haemolysis, and acute non-haemolytic blood transfusion reactions

A

Similar, but acute non-haemolytic usually without haemoglobinaemia/uria

66
Q

What is the most common cause of an acute non-haemolytic transfusion reaction?

A

Bacterial contamination

67
Q

What is the most common cause non-haemolytic transfusion reactions?

A

IgE and mast cell emdiated

68
Q

Following a blood transfusion, what are the following signs indicative of?
Anaphylaxis i.e. urticaria, dyspnoea, vomiting

A

Non-haemolytic reaction

69
Q

How do non-haemolutic, non-hypersensitive transfusion reactions occur?

A

Suspected due to broken down platelets or WBCs releasing inflammatory mediators. reduced by pre-sampling leukoreduction

70
Q

Describe the signs of acute transfusion reactions (<24h)

A
  • Pyrexia
  • Depression
  • Dyspnoea, tachypnoea, coughing
  • Tachycardia or bradycardia
  • Vomiting
  • Vocalisation (cats)
  • Urticaria (esp. dogs)
  • Erythema or pruritus
  • Tremors or seizures-
  • Shock
  • Cardiopulmonary arrest
71
Q

Describe the clinical signs of delayed transfusion reactions (>24hours)

A
  • Fever
  • Anorexia
  • Jaundice
  • Often subclinical
  • May get non-regenerative anaemia (e.g. myelodegenerative) in some dogs
72
Q

What is a logical approach to non-haemolytic transfusion reactions

A
  • Stop, provide antihistamine and possibly glucocorticoids

- May require circulatory support

73
Q

What is a logical approach to any transfusion reaction?

A
  • Stop immediately
  • Clinical exam, esp: cardio, temp, haemoglobinaemia/uria
  • Supportive treatment as indicated: fluids, corticosteroids, oxygen, antihistamines, adrenaline, diuretics
  • Check blood typing or cross matching
  • Check blood bag for evidence of lysis
74
Q

List your differentials for a 3 day old foal that was initially normal and is now presenting with marked icterus, dark urine, loose yellow faeces, too weak to stand and unable to suckle

A
  • Neonatal isoerythrolysis
  • Portosystemic shunt
  • Congenital liver dys/hypo/aplasia
  • Sepssi
  • Bacterial toxin
  • EHV-1
  • Clostridium leading to necrotising hepatitis
  • Dehydration (dark urine)
  • renal disease
  • Hypoglycaemia (weakness)
75
Q

What tests should be performed when presented with an icteric foal?

A
  • Direct Coomb’s test
  • Biochem and haematology
  • Urinalysis
76
Q

What emergency treatment should be provided to an icteric foal?

A
  • Supplemental oxygen via nasal tube
  • Urinary catheter
  • Fluid therapy (vol depends on fluid deficit, 1L initially as a bolus)
77
Q 
What are the following haematology findings in a foal indicative of?
RBC low, Hb low, PCV low 
Neutrophils high 
Monocytes high 
Low plasma proteins 
High icterus index = active jaundice
Lactate high
A

Haemolytic anaemia, most likely neonatal isoerythrolysis

78
Q

Outline the treatment for a foal with neonatal isoerythrolysis

A
  • Fluids
  • Blood transfusion (care re. blood transmitted diseases, wash with saline and centrifuge dam’s blood to remove alloantibodies)
  • Give milk
  • Antimicrobial therapy e.g. cefquinome
79
Q

What IgG titres would indicate failed and successful antibody transfer following plasma transfusion in a foal?

A
  • Failed: below 300-400mg/dL

- Successful: >8g/dL

LCB2 (14 decks)

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