Lab 3 - Changes in haemostasis Flashcards
Name the tests performed by the side of the animal
- Signa of increased bleedomg tendancy
- Capillary recistance (human)
- Bleeding time
- Clotting time (first fibrin strand appear)
- Appearance of the clot - clotting time on difference surfaces
- Clot retraction time
Bleeding time and bleeding mucosal bleeding time is used to test for what
Theombocytopenias(fewer platelets), thrombocytopenias (dysfunctional platelets) and vasopathies(cell wall dysfunction)
Bleeding time influenced by this - not bye the coagulation cascade (coagulopathys)
Normal BMBT
3-5mins
Coagulation time is used to test what
Coagulationpathy (disfunctionnin coag. Cascade)
When will the forst fibril stand appear
1-2mins
Clotting time
On watch glass - 7-15mins (paraffin or wax)
In plastic syringe - 10-12mins
In glass tube - 4-5mins
In activated CT tube - 3min (SiO2)
5 causes pf theombocytopenia
- Decr prod in bone marrow (bm suppression - chemo, toxins)
- DIC (small blood clot formation)
- Blood/platelets trapped in spleen -> splenomagaly and hypovolemia
- Incr destruction of platelets (immune thrombooenia)
- Subacute bleeding; blood/platelet loss
Size of platelets in different animals
3-5fl horse, sheep and cattle
7-8fl dogs and swine
10-15fl cats
Causes of thrombocytopathy
- Improper development(hereditary glucoprotein deficiancy)
- Von willebrands disease (clotting factor missing/defect)
- Liver failure, uraemia etc
When are platelet counts important?
When the bleeding time/buccal mucosal bleeding time is increased or petechies are visible
(-> problems with stopping bleeding)
What is the normal prothrombin time, and how is it evaluated?
10-15sec
Extrinsic pathway - by external trauma - quickest. Activated by tissue factor(thromboplastin=factor III) from rat uterus tissue
What is the normal activated partial thromboplastin time and how is it evaluated
20-30sec
Intrinsic pathway as the imitated internal trauma of the micronised silica (imitates free collagen from vessel) and also TF3(rabbit brain) and Calcium
Intrinsic coagulation cascade
Collagene, APTT
12-11-9-8-5
->
10-2-1-13
-> polymerized fibrin
Extrinsic coagulation cascade
Prothrombin, tissue damage 3-7 -> 10-2-1-13 -> polymerized fibrin
What are the three steps of haemostasis
- vasoconstriction
- Platelet aggregation and adherance, primary thrombus
- Coagulation cascade, polymerized fibrin network
A more precice wat to measure fibrin degr products
D-dimer levels instead of fibrin degr products, which are derived from fibrin only
Attach to latex particles for quantitative measure on dark surface