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
DIC
Disseminated intravascular coagulopathy
Fdp or D-dimer test is often first sign of this disease
What characterises dic
blood clots form throughout the body, blocking small blood vessels. Usually a secondary problem developed after eg. Necrosis of big tumors, pancreatitis - diseases causing severe tissue damage and necrosis
How is von willebrand disease detected?
Detection of lack of von willebrand related antigen, use eg. Platelet aggregation test
Sample type for coagulation time
Non coagulated, fresh, native blood, 2 syringe method
Sample type for platelet count
K2 or na2 EDTA anticoagulated blood
Platelet aggregation test and tests for voagulopathies and fibrin degr. Products sample type used
Citrated blood - de-calcinated plasma by binding the ca2+ to citrate
aggregation test
Used for aggregation test to measure disfunction in aggregation of platelets
Citrated blood sample, use upper layer ➡️ into cuvette with drug(ADP) causing exaggerated aggregation ➡️ aggregation cause clearing up of fluid which decr the absorbancy. We use a spectrophotometer to measure.
Decr A means good platelet function
Thrombin time
Does not check intrinsic or extrinsic, only the time throbin uses to convert fibrinogen into the insoluble fibrin clot
(Thrombin mixed with citrated blood + fibrinogen and XIII
