TV4101 - SAM - Haemostasis 1

Primary Haemostasis involves?

When does it occur?

1st haemostasis when BV is damaged but clot is unstable and can be easily washed away

Primary vs 2ndary

Of these defects - how common is the defect from primary or secondary respectively

2ndary Haemostasis involves?

Tertiary Haemostasis - Involves?

Why?

Clot needs to break down or else blood flow is impacted → hypoxia → death

Finish table

Which is more commonly in superfiical mm bv damage to resolve it?

Which is in deep body cavities more often?

Primary

Secondary

2ndary haemostasis

Components?

Tests?

CX?

Important Dz?

2ndary haemostasis

Components?

Tests?

Important Dz?

Sample Collection

What is used?

Catheter aspects?

Citrate vaccum tube

Avoid heparinised catheters (affects coagulation)

Non-heparin catheters can be used but flush with 5ml saline and then discard 6x dead space (5ml)

Sample Collection

Care is important - we need to minimise?

Term for doing this?

Traumatic venepuncture leads to?

Activation of PLT, coagulation and fibrinolytic systems

“Clean Stick” - free flowing blood and clean venepuncture on first attempt

Exposure of Tissue factor → activates pathways to be tested (causes coagulation)

Sample Collection

Vaccuum?

Mixing?

Avoid excess vaccum - may cause turubulance and platelet activation

Mix immediately - gentle but thorough

Sample Collection

Volumes aspects

Clinical sig of underfilling?

Underfilling may cause prolonged PT and APTT (falsely claims dz)

Sample Collection

Aspects when lab is kinda far away and need to keep it relatively stable

Keep it cold when its sent

What is the functional role of inhibitors of haemostasts like Anti-thrombin III?

Dx tests for Haemostasis - Primary

What aspects do we test?

How do we test them?

Specimen type used if applicable?

Purpose of vWB?

With damaged vessel → help platelets stick to vessel and each other → aggregation

Dx tests for Haemostasis - Primary Haemostasis

PLT concentration

Methods to count? Features?

If less than 3 plt per high power field - you must count ten fields to get accurate count

Dx tests for Haemostasis - Primary Haemostasis

PLT function

Methods to count? Features?

Dx tests for Haemostasis - Primary Haemostasis

PLT function test via Buccal Mucosal Bleeding time

What might inc BMBT?

Dx tests for Haemostasis - Primary Haemostasis

PLT function test via Buccal Mucosal Bleeding time

What are normal times?

What is prolonged time?

Prolonged Time > 5 minutes in small animals

(dog normal < 4 minutes, cat < 3 minutes)

What is this?

What is it for?

How it is used? Steps?

Simplate Device

Primary Haemostasis - PLT function test via Buccal Mucosal Bleeding time

1. Roll up upper lip and secure with gauze strip

2. Make a cut in lip using device and start the time

   a. Cut is 5mm x 1mm - superficial enough to only need Primary haemostasis resolution

3. Filter paper is used to blot awat excess blood without touching or disturbing incision

4. End point - when bleeding stops

What is this?

What is it for?

Reference values?

If above these values i.e. increased, what can be interpreted

BMBT performed by Francke needle

Measuring BMBT for Platelet function of primary haemostasis

Dog, horse, cow 2- 5 min (cat < 3minutes)

Indicates vascular lesions or capillary fragility lack of platelets and/or defects of platelet function

Primary Haemostasis

PLT function test for Clot Retraction Time (CRT)

Technique?

1. 2ml blood from two animals and a control animal in glass tubes with anticoagulant to clot at 37 degrees

2. After 1 hour, compare clot retraction in 3 vials and serum prod should be 30-50%

Primary Haemostasis

PLT function test for Clot Retraction Time (CRT)

Which is which in each of these vials?

Primary Haemostasis

PLT function test for Clot Retraction Time (CRT)

Interpretation

Clot retraction should be recorded as X? based on X?

Normal, equivocal, or defective, based on a normal retraction of about 30-50%

Primary Haemostasis

PLT function test for Clot Retraction Time (CRT)

Interpretation

What can produce defective clot reaction?

What inc clot reaction?

• Thrombocytopenia/pathy, erythrocytosis, and hypofibrinogenaemia produce a defective clot retraction.

• Anaemia increase clot retraction.

Primary Haemostasis

PLT function test for Clot Retraction Time (CRT)

Interpretation

Clot lysis?

In DIC the clot is often small and ragged, partially disintegrated (due to excess of plasmin), and after 24 hours the clot modification are more pronounced

Primary Haemostasis - vWF

Testing vWF using Ag assay

What samples are used?

Primary Haemostasis - vWF

Testing vWF using Ag assay

Analytical Interpretation

Is reported as?

Reported as % relative to pool of healthy species reference

Primary Haemostasis - vWF

Testing vWF using Ag assay

Analytical Interpretation

The different parameters and meaning?

 Dog with vWF : Ag >70% are considered free of vWD trait

 Dog borderline vWF : Ag 50-69% carrier, but no risk (repeat test)

 Dog with vWF: Ag <50% considered carriers of vWD trait

: transmit trait to offspring

: risk of clinical vWD increased with lower vWF : Ag

 Dog that bleed – most <35%

Primary Haemostasis - vWF

Testing vWF using Ag assay

Analytical Interpretation

Falses and causes?

Primary Haemostasis - vWF

Testing vWF using DNA

How do?

Results?