Haemostasis 1

What is haemostasis?

What is haemostasis?

stopping bloodflow

what are the 4 stages of normal haemostasis?

1.     localized vasoconstriction at the site of injury

2.     adhesions of platelets to damage vessel wall and formation of a platelet aggregate or plug

3.     activation of the coagulation cascade leading to fibrin formation, reinforcing the platelet plug

4.     activation of the fibrinolytic system which digests the haemostatic plug, re-establishing vascular patency

What are platelets?

• Small non-nucleated cells

• Fragments of megakaryocyte cytoplasm

• Essential for primary haemostatic plug

What is normal and deficient platelet count?

Normal platelet count is 140-350x10^9L

Deficiency of less than 20 x 10^9 per litre=Spontaneous bleeding

what is the name for a reduced platelet count and increased platelet count?

1.     Thrombocytopenia = reduced platelet count

2.     Thrombocytosis = increased platelet count

What is primary and secondary haemostasis?

primary - involves vessel wall (collagen), platelets and von Willebrand factor

Secondary - involves coagulation cascade

What are the presenting problems when primary haemostasis is affected?

• Involves abnormalities in the patient’s: vessel wall (changes to collagen), platelets, and von Willebrand factor

• VWB factor is one of the factors involved in primary haemostasis and the binding of platelets to the endothelial lining of vessels.

• Present with bruising, bleeding from cuts, heavy periods and surgical bleeding

What are the presenting problems when secondary haemostasis is affected?

• joint and muscle haematomas

• surgical bleeding

• Bruising is not prominent.

As long as the primary haemostasis is okay, as the platelets will form that initial clot- they just wont have the reinforced secondary clot.

What are some of the things that you would investigate when history taking with ppl with blood disorders?

1.     Bleeding after dental extractions

2.     Bleeding after surgery

3.     Family history of a bleeding disorder

4.     Drugs e.g., aspirin, warfarin, cytotoxic

5.     Alcohol

What do we look for in an examination regarding bleeding disorders?

1.     Ecchymoses (Bruises)

2.     Purpura - purple discolouration of skin (internal bleeding)

3.     Hemarthrosis (bleeding in joints)

4.     Damaged joints

5.     Anaemia (due to bleeding)

6.     Signs of liver disease

What tests would you do for bleeding disorders?

1.     Full Blood Count - Platelet count

2.     Clotting screen

3.     Prothrombin time (PT)

4.     APTT

5.     Fibrinogen (how much in blood)

6.     Bleeding time or PFA (automated Platelet Function Analysis)

what do the following words mean?

- menorrhagia

- epistaxis

- haemoptysis

- haematemesis

- haematuria

- melaena?

1.     Menorrhagia = Heavy menstrual periods

2.     Epistaxis = Nosebleed

3.     Haemoptysis = Coughing blood

4.     Haematemesis = Vomiting blood

5.     Haematuria = Blood in the urine

6.     Melaena = Black stool due to bleeding from the upper gastrointestinal tract

what are the different treatments for the following?

- haemophilia A

- haemophilia B

- thrombocytopenia

- warfarin overdose

1.     Haemophilia A - FVIII concentrate

2.     Haemophilia B – FIX concentrate

3.     Thrombocytopenia – Platelet transfusion

4.     Warfarin overdose – Vitamin K

what are some of the inherited vascular bleeding disorders?

Vascular disorders = involving primary haemostasis

Hereditary Haemorrhagic Telangiectasia (HHT)

• can cause significant bleeding with little pressure, nose bleeds, anaemia (from blood loss).

Ehlers-Danlos syndrome

• Inherited condition of connective tissues

• stretchy skin and blood vessels

• therefore not able to produce same haemostatic plug

What are some coagulation factor disorders?

1.     haemophilia A+B

• Sites of bleeding- joints, muscles, post trauma, post operative

2.     von willebrands

3.     deficiency of fibrinogen and all the factors

How to treat mild haemophilia a?

Desmopressin (DDAVP)- this releases factor VIII from the endothelium

normalises factor VIII levels, for just a few hours

How do you treat all severities in haemophilia

recombinant factors used in UK

can be plasma derived abroad so risk of infection

what is blood thrombosis?

Thrombosis is blood coagulation inside a vessel

describe arterial thrombosis

–high pressure

–platelet rich

–examples: myocardial infarction (MI), stroke

–treat with antiplatelet drugs

describe venous thrombosis

–low pressure

–fibrin rich

–examples: deep vein thrombosis (DVT), pulmonary embolism (PE)

–treat with anticoagulants

what are the acquired risk factors of venous thrombosis?

- Age

- Surgery/Trauma

- Cancer/Serious Illness

- Pregnancy/Contraceptive pill

What are the inherited risk factors of venous thrombosis?

1.     Antithrombin deficiency

2.     Protein C deficiency

3.     Protein S deficiency

what are the arterial thrombosis risk factors?

1.     Smoking

2.     Obesity

3.     Hypertension

4.     Diabetes mellitus

5.     Older age

No inherited risk factors