Flashcards in Bleeding disorders Deck (20):
Describe the origin of a pulmonary embolus and a stroke.
Which prophylactic drugs are given to prevent each?
PE originates in the venous system. Administer heparin, an anti-coagulant drug.
Stroke occurs when a clot originating from the arterial system enters the cerebrospinal circulation/embolus. Atrial fibrillation puts patients at risk of this. Administer warfarin, anti-coagulant drug.
Outline and describe the three main causes of bleeding.
Vascular disorders (vessel wall problems). Can be Inherited (hereditary haemorrhagic telangiectasia which causes malformations of capillaries in skin and organs; ehlers-danlos syndrome) and acquired (scurvy, steroids, senile)
Platelet disorders e.g. thrombocytopenia, defective function
Defective coagulation subdivided into inherited (haemophilia) and acquired (liver failure which disrupts clotting factor secretion)
What is the difference between bleeding caused by vascular and platelet disorders vs coagulation disorders?
Bleeding into mucous membranes and skin
Bleeding into joints and soft tissue
Consider platelet disorders. At which critical level is thrombocytopenia diagnosed?
When is it considered a medical emergency?
What causes it?
<150 x10^9 / L
Thrombocytopenia requiring emergency treatment is a platelet count below 50,000 per microliter (<50x 10^9 / L)
Epistaxis, GI bleeds, menorrhagia, bruising, some rare inherited conditions, COMMON acquired causes e.g.
1. Immune thrombocytopenia
2. Drug use
3. Disseminated intravascular coagulation
Treatment for immune thrombocytopenia ?
Steroids or intravenous immunoglobulins or occasionally splenectomy
Describe the aetiology of disorders of platelet function
May present as normal platelet count!
INHERITED (RARE): Glanzmann's
ACQUIRED: aspirin, non-steroidal anti-inflammatory drugs (NSAIDs) . This. are examples of iatrogenic causes.
Describe the use of EDTA in terms of blood clotting
It stops blood clotting by binding calcium. Calcium is required in the action of prothrombinase
Where is the defect in haemophilia A and B?
Their clinical symptoms are identical. What are they?
A- Clotting factor 8
B- Clotting factor 9
X linked so affects males more
Spontaneous bleeding into joints and muscles
unexpected post op bleeding
Chronic debilitating joint disease
Outline 6 tests of coagulation
1. PT = Prothrombin time . It assesses the extrinsic pathway. Essential in patients on warfarin
2. APTT= Activated partial thromboplastin time
Assesses the intrinsic pathways
3. TT= Thrombin time
4. Fibrongen level
5. Factor level assay
6. Bleeding time
What would coagulation tests look like for a patient with haemophilia?
Prolonged APTT, Normal PT, Low factor VIII/IX (<1% =severe, 1-5%= moderate, >5%=mild)
What is the treatment for haemophilia ?
Historically- fractionated human plasma
Current treatment- infusions of recombinant factor VIII or Into 50-100%
Prophylactic treatment has revolutionalised management of haemophilia patients.
Describe the von Willebrand disease
Results in decreased von Willebrand factor which is a large multimeric protein that carries factor VIII in blood. It also binds platelets to endothelial collagen.
Mucocutaneous, nose bleeds, menorrhagia
What would coagulation tests look like for a patient with von Willebrand disease?
Prolonged APTT, normal PT, low vWF level/function, low factor VIII level, prolonged bleeding time, defective platelets
What is the treatment for von Willebrand disease?
Desmopressin (DDAVP), anti-fibrinolytic and plasma products
Outline three acquired coagulation diseases
1. Non-inherited haemophilia
2. Liver disease ( defects in synthesis of CP, impaired platelet function & fibrinolysis)
3. Disseminated intravascular coagulation (DIC)- releases of pro-coagulant material into circulation, causes bleeding and thrombosis to occur
Consider anti-coagulants. Which anti-coats are iatrogenic?
Direct oral anti coagulants?
Warfarin - used in PE, DVT, Afib, Prosthetic valves
Heparin- used tin MI, PE, DVT
Direct thrombin inhibitors: Dabigatran, Urgatrobin
Factor Xa inhibitors: Rivaroxaban, apixaban
What is the use of Vitamin K in terms of blood clotting?
What causes Vitamin K deficiency?
Required for gamma-carboxylation of factors 2, 7,9,10
Inhibited by warfarin
Deficiency due to malabsorption of vitamin k, billiard obstruction (jaundice), haemorrhagic disease of newborn (give 1mg @ birth)
What effect does warfarin have on coagulation tests?
What must happen to patients on warfarin?
Prolonged extrinsic pathway (assessed by PT)
They must be monitored by the international normalised ratios (INR)
Target INR of 2.5 for DVT, PE & AFib
Target INR of 3.5 for recurrent VTE or metal heart valves
Warfarin is used a rat poison. Describe the discovery of warfarin?
Farmer discovered treatment for cattle with mysterious haemorrhagic disease.