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Year 3 MOD > Clinical Pathology- Haematology: Approach to Bleeding Patient and Transfusion Medicine > Flashcards

Clinical Pathology- Haematology: Approach to Bleeding Patient and Transfusion Medicine Flashcards

1
Q

If a patient arrives and is bleeding how should you approach the animal?

A

Attempt to quantify blood loss

Identify life threatening situation- hypovolaemic shock, severe anaemia, brain or pulmonary haem

Establish venous access and collect samples for test

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2
Q

How can the patient be stablilised?

A

Control of haemorrhage- pressure

Fluid replacement:
Volume replacement crystalloid if hypovolaemic
‘shock rates’ recomend a bolue of 1/5-1/4 animals blood volume
Blood transfusion if significant anaemia

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3
Q

Briefly describe the process of haemostasis?

A

Vessel injury

Vascular contraction- primary plug

Primary haemostasis- endothelium, platelets, von willebrand

Secondary haemostasis- coagulation cascade resulting in generation of thrombin

Tertiary haemostasis- fibrinolysis- plasmin

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4
Q

What is needed for primary haemostasis?

A

von Willebrand factor

platelets

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5
Q

What are clinical signs of primary haemostasis defects?

A

‘Small holes’

due to lack of platelets/poor platelet function

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6
Q

What are clinical signs of secondary haemostasis defects?

A

Result of deficiency in clotting factors

Tend to present more acutely with life-threatening blood loss

Subcutaneous or cavity bleeding

Haematoma formation

Pulmonary haemorrhage

Haemarthrosis

‘Large holes’

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7
Q

What in house tests can be used to test for primary and secondary haemostasis disorders?

A

Haematology- smear examination and platelet estimation

Biochemistry

Whole blood clotting time- uncommon

Activated clotting time- uncommon

Buccal mucosal bleeding time

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8
Q

Where should thepatient be venepunctured if worried aboiut haemostasis disorders?

A

Cephalic/Saphenous vein

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9
Q

What tests can be used to differentiate between primary and secondary haemostasis disorders?

A

Primary coagulopathy- test platelet function or number:
manual count, buccal mucosal bleeding time, von Willebrand factor

Test of coagulation:
Prothrombin time
Activated partial thromboplastin time
Activated clotting time- rarely used
Test specific factor levels

Test of fibrinolysis- fibrinogen degredation products, D-dimers

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10
Q

How much blood can healthy animals usually lose?

A

15-25% of blood

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11
Q

What disorders of primary haemostasis are there?

A

Thrombocytopenia

von Willebrands disease

Thrombocytopathia- v rare

Vascular disorders- v rare

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12
Q

What can cause thrombocytopenia?

A

Most common cause

Lack of production- bone marrow disorders, drug toxicosis

Increased consumption- DIC, acute severe haemorrhage

Increased destruction- immune mediated- primary/secondary

Increased sequestration- splenic torsion

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13
Q

What are the two types of inherited thrombocytopenia?

A

Inherited macrothrombocytopaenia- CKCS, norfolk and cairn terriers

Breed-associated thrombocytopenia- Sighthounds with lower platlet counts

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14
Q

What is the difference between primary and secondary immune mediated thrombocytopenia?

A

Primary- IgG binding to platlets resulting in their destruction, marked thrombocytopenia

Secondary- secondary to drugs, infectious disease or neoplasia, antibiotics most common

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15
Q

How is IMTP diagnosed?

A

Full clinical history- including drugs and travel history

Full clinical exam including opthalmological exam

Haematology with blood smear evalutation

Biochemistry +/- urinalysis

Thoracic radiographs

Abdominal ultrasound

Idexx 4DX SNAP

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16
Q

How is IMTP treated?

A

Secondary- treat underlying disease or discontinue offending drug

Glucocorticoids mainstay of therapy for primary disease:
regulator of gene expression, effects humoral and cell-mediated immune system

Whole blood transfusions can provide short-term haemostasis despite a negligible increase in platelet count post-transfusion

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17
Q

What is platlet dysfunction and what can cause it?

A

Animals who bleed excessively despite normal platelet count and coagulation profile

Causes:
Drug therapy
von Willebrands disease
Hepatic disease
Renal disease
Hyperproteinaemias
Bone marrow neoplasia

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18
Q

What is von Willebrands disease?

A

Deficiency of von Willebrand factor- inherited, acquired with severe aortic stenosis

vWF is synthesised and stored by endothelial cells- vital for platelet adherence

Mucosal surface bleeding or excessive bleeding following surgery

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19
Q

How is von Willebrands disease treated?

A

Cryoprecipitate- rich in VII, fibrinogen and vWF, whole blood or fresh plasma

DDAVP- 1-desamino-8-D-arginine vasopressin increases vWF release

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20
Q

What causes disorders of secondary haemostasis?

A

Deficiency of clotting factors

Inherited uncommon- haemophilia A/B

Usually acquired- vitamin K antagonism (deficency), severe liver disease, DIC

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21
Q

What can cause vitamin K deficiency?

A

Most commonly caused by ingestion of vitamin K antagonists- rodenticides

Other causes- hepatic failure, decreased absorption

Vit K involved in production/activation of factors II, VII, IX, X

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22
Q

What are the clinical signs, diagnosis and treatment of vitamin K deficiency?

A

Clinical Signs:
typically 2-5 days after ingestion- epitaxis, melaena, haemoptysis, haematoma, eccymoses, haematuria, gingival bleeding, haemoabdomen, haemothorax

Diagnosis- clinical history, signs, coatulation testing

Treatment- vit K therapy, not IV, recommended for 2-4 weeks, FPP transfusion in emergency

23
Q

What does DIC stand for and what does it cause?

A

Disseminated intravascular coagulation

Widespread activation of coagulation leads to thrombosis and multiorgan failure

24
Q

What are the common underlying casues of DIC?

A

Infectious disease, immune mediated, neoplasia, trauma, heat stoke, cardiac disease, parasites, toxicity

25
Q

What can cause acute DIC?

A

Presentation with thrombotic disease

Haemorrhage
Thrombosis
Multiorgan failure
Metabolic acidosis

26
Q

What are the lab abnormalities of acute DIC and how is it treated?

A

Lab abnormalities:
Prolonged clotting times, reduced ATIII, thrombocytopenia, schistocytes, increased FDPs/D-dimers, decreased fibrinogen- poor prognosis

Treatment- treat underlying cause, plasma, heparin, whole blood

27
Q

What are FDPs and what causes their increase?

A

Fibrinogen degredation products

Increased- DIC, thrombotic disease, reduced hepatic clearence

28
Q

What are D-dimers more sensitive indicators of and why?

A

D-dimers are more senstitive indicators of fibrinolysis in canine DIC

because they are specific for breakdown of cross linked fibrin

29
Q

What is PT and aPTT?

A

PT- prothombin

aPTT- activated partial thromboplastin time- blood coagulation test

30
Q

Can you fill in the following table?

A
31
Q

When should a patient be given a blood transfusion?

A

Based on clinical signs- signs of reduced oxygen delivery- taccycardia, lethargy, collapse, weakness

Transfuse dogs with PCV 15-20% and cats of 10-15%

32
Q

How long does it take PCV to decrease after acute haemorrhage?

A

Lag period of 24 hours

33
Q

What decides what blood product should be used?

A

Replace like with like

Haemorrhage there is equal loss so whole blood preferred

34
Q
A
35
Q

What blood product should be used with blood loss, haemolysis and coagulopathy?

A

Blood loss- fresh whole blood or packed red cells

Haemolysis- packed red cells

Coagulopathy- fresh frozen plasma, regular plasma, cryoprecipitate

36
Q

What different blood transfusion products are availible and what are its constituents?

A

Whole blood- 35% RBC, 65% plasma

Packed red cells- 60-80% RBCs, plasma 40-20%

Fresh frozen plasma- 99.9% I-XI clotting factors and vWF

Regular plasma- 99.9%- II, VII, IX, X clotting factors

37
Q

What is the UK blood bank and how does it work?

A

Charity that provides all blood products and equipment as well as guidance

Can deliver 24/7- cost depends on distance

Provide cross match with IDEXX

No feline or platelet products

38
Q

Within how long does fresh whole blood need to be used?

A

Within the first 24-48 hours following collection

After this there is a decrease in liable clotting factors and the product becomes whole blood with 21 day shelf life

6 hours after colleciton there is no platelets in blood

39
Q

How long is fresh frozen plasmas shelf life?

A

Centrifuged blood within 6-8 hours, contains clotting factors

1 year shelf life

40
Q

What information needs to be known about patients blood types before infusion?

A

Ideally give type-specific in dogs as it has a longer life span

If in doubt or an emergency give dogs DEA -ve

In cats it is imperative that type specific blood is given as can lead to acute haemolytic transfusion reactions

Not necessary for adminstration of plasma products

41
Q

Why does blood type of patients usually need to be known?

A

RBCs have different antigens

If a patient has a specific antigen it will not have antibodies against that protein

If they do it will cause RBC haemolysis

42
Q

Why can dogs be given any blood in an emergency but cats cannot?

A

Dogs rarely have naturally occuring auto-antibodies so will rarely have an acute haemolytic transfusion reaction- auto-antiboides are usually produced 3-5 days after transfusion- the first one is free

Cats do have naturally occuring auto-antibodies, non-matched blood causes acute haemolytic reaction

43
Q

What antigen is found on the surface of canine RBCs?

How is this used for typing?

A

DEA, the only one we can type is the DEA 1 system

Typing:

  • DEA 1-ve recieving DEA 1+ve blood for the first time will develop delayed haemolytic transfusion reaction
  • DEA 1+ve dogs reciving DEA 1-ve blood for the first time will not have any DEA 1 antigens giving longer lifespan of RBCs
44
Q

How is cats blood typed?

A

In cats the main RBC antifen is the A/B system where A is autosomal dominant to B

All B cats have auto-antibodies for A

Not all cats have auto-antibodies for B

45
Q

What are the different ways blood can be tested?

A

Gold standard is testing in an external lab- there is rarely time though

Most common methods are rapid vet-card method and alvedia cassette method

Cassette method easier to interpret and autoagglutination does not need to be ruled out

46
Q

What is cross matching?

A

Cross matching looks for reactions between red blood cell antigens and antibodies in the donor and recipient

Performed by mixing two bloods and looking for evidence of haemolysis

47
Q

What is major and minor cross matching?

A

Major- looks for the presence of auto-antibodies in plasma

Minor- looks for the presence of auto-antibodies in donors plasma against recipients RBCs

48
Q

How much blood should be tansfused to the patient?

A

Restrictive transfusion target- 21-25% PCV just as good as liberal 35-40%

Use formulas as a rough guide

Round up to the nearest bag/cat

Wide variation in post-transfusion PCV

49
Q

How should transfusion be administered?

A

IV/IO

All administered slowly to prevent transfusion reactions
Consider equipment and ability to monitor patient
Maintaining sterility is vital
Must be fiven through transfusion set with in-line filter
Dogs better drip-by-drip, cats a syringe

0.5-1ml/kg/hr for first 30 mins
4-6ml/kg/hr thereafter

only flush IV with saline

No access to food

50
Q

What should be monitored for a transfusion?

A

Monitoring for signs of transfusion reactions during and after

Monitor HR, RR, rectal temp

Watch for anaphylaxis, uticaria, nausea, vomiting

51
Q

What haemolytic transfusion reactions can occur?

A

Type II with varying degrees of severity

Severe acute haemolytic reactions- obvious- tachycardia, tachypnoea, pyrexia, haemolysis of serum, haemoglobinuria

Mild delayed haemolytic reactions- slow removal of RBCs by monocytic phagocytic syndrome

52
Q

What respiratory transfusion reactions can occur?

A

Increase in respiratory rate- common but could be stress or disease

TRALI- transfusion induced acute respiratory distress syndrome

TACO- transfusion related cardiovascular overload- cats or patients with cardiac/renal disease

53
Q

How should transfusion reactions be managed?

A

If reaction suspected stop transfusion

If in doubt, temporarily stop and and restart at slower rate

If cause cannot be found symptomatic treatment should be administered

54
Q

What non-heamoltyic transfusion reactions can occur?

A

Most common is non-haemolytic pyrexia and anaphylaxis

Reactions vary from tachycardia, tachypnoea, and pyrexia but can also be uticaria

Year 3 MOD (40 decks)

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