Bleeding Disorders and Haemostasis - Part 1

Bleeding Disorders (Part 1)

• Bleeding disorders are a significant concern in oral health.
• This session is aimed at educating dental hygienists/therapists about bleeding disorders.
• GDC learning outcomes include explaining general and systemic diseases, relevant physiology, recognizing oral cavity abnormalities and patient concerns, and adjusting treatment plans according to patient needs.
• Learning outcomes also include understanding the impact of medical conditions and psychological conditions.

Haemostasis

• Haemostasis is the body's physiological response to vascular injury, preventing significant blood loss.
• Three main events in haemostasis are:
  • Vascular system: the injured vessel constricts.
  • Platelet system: platelets aggregate to form a plug.
  • Coagulation cascade: the cascade produces a fibrin plug.

Aggregation of Platelets

• Platelet activation involves three stages:
  • Adhesion: platelets stick to the damaged blood vessel wall.
  • Secretion: platelets release substances to promote clotting.
  • Aggregation: platelets clump together to form a plug.

The Coagulation Cascade

• The coagulation cascade is a complex series of reactions involving various clotting factors.
• The cascade has two main pathways:
  • Intrinsic pathway: initiated by contact with a damaged surface.
  • Extrinsic pathway: initiated by tissue damage.

Classification of Bleeding Disorders

• Bleeding disorders can be categorized into disorders of:
  • Blood vessels
  • Platelets
  • Coagulation

Disorders of Blood Vessels

• Inherited disorders include connective tissue disorders (e.g., Ehlers-Danlos Syndrome) and hereditary hemorrhagic telangiectasia (HHT).
• Acquired disorders include severe infections (e.g., meningococcal, typhoid), medications (e.g., sulphonamides), and other conditions (e.g., vitamin C deficiency, senile purpura).

Disorders of Platelets

• Disorders of platelets include:

  • Thrombocytopenia (low platelet count)
    • Idiopathic Thrombocytopenia Purpura (ITP)
    • Liver disease
    • Renal disease
    • Chemotherapy
    • Radiotherapy
    • Connective tissue disorders
    • Rare diseases (Bernard-Soulier, Jacobsen, Lowe)
    • Antiplatelet drugs

• Thrombocytopenia can result from decreased/failed platelet production, destruction of circulating platelets or from platelet function disorders.

• Idiopathic Thrombocytopenic Purpura (ITP) is an autoimmune disorder resulting from the immune system attacking platelets. It has acute and chronic forms.

Disorders of Platelets cont.

• Liver disease affects blood clotting. The liver produces clotting factors, and liver disease can lead to mal-absorption of fat-soluble vitamins such as vitamin K.
• Patients with chronic liver disease and post-operative patients dependent on alcohol may have increased postoperative bleeding due to decreased clotting factor production, bone marrow suppression, or folate deficiency causing thrombocytopenia.
• Malnutrition from heavy drinking can decrease the synthesis of vitamin K-dependent clotting factors.
• Renal disease impairs haemostasis due to impaired platelet production, a decrease in platelet factor 3 and vasodilation. Renal failure patients taking heparin may also have impaired haemostasis.

Disorders of Coagulation

• Inherited disorders include Haemophilia A, Haemophilia B (Christmas Disease), and Von Willebrand Disease.
• Acquired disorders include liver disease, hematological malignancies, and anticoagulant drugs.

Haemophilia A

• Most common type of haemophilia.
• Deficiency in clotting factor VIII.
• X-linked recessive condition affecting mostly males. Females can be carriers.
• Presents with bleeding (nosebleeds, bleeding gums, easy bruising, joint pain and stiffness).

Haemophilia B (Christmas Disease)

• Less common than Haemophilia A.
• Deficiency in clotting factor IX.
• X-linked recessive condition affecting mostly males.
• Presents with similar bleeding symptoms as Haemophilia A.

Von Willebrand Disease

• Most common hereditary coagulation abnormality.
• Deficiency or dysfunction of von Willebrand factor (vWF).
• VWF is crucial for factor VIII and platelet adhesion and aggregation.
• Presentation similar to platelet dysfunction.
• Treated with medications like desmopressin, tranexamic acid, and factor VIII replacement.

Antiplatelet and Anticoagulant Drugs

• Antiplatelet drugs are used to prevent blood clots and include:

  • Aspirin
  • Clopidogrel
  • Dipyridamole
  • Ticagrelor
  • Prasugrel

• Indications include ischaemic heart disease, previous myocardial infraction, atrial fibrillation, coronary stent placement, previous stroke and renal transplant.

• Anticoagulant drugs are used to prevent blood clots.

  • Warfarin
  • Direct oral anticoagulants (DOACs) : Rivaroxaban, Apixaban, Edoxaban, Dabigatran
  • Heparin

• Indications for anticoagulants include stroke, transient ischaemic attack, deep vein thrombosis, pulmonary embolism, atrial fibrillation, and heart valve surgery.

Warfarin

• Vitamin K antagonist that blocks enzymes requiring vitamin K to produce clotting factors.
• Monitored using the international normalized ratio (INR).
• Target INR can vary depending on the condition.
• Long half-life, effect begins in 8-12 hours, with maximal effect at 36 hours and lasts 72 hours.
• Many interactions with other medications.

Direct Oral Anticoagulant Drugs (DOACs)

• Work by inhibiting factor Xa or thrombin.
• Rapid onset of action (1-4 hours).
• Fewer food and drug interactions than Warfarin.
• Usually no need for routine INR monitoring.
• Some have reversal agents.

Heparin

• Short half-life (1-2 hours).
• Primarily used intravenously in hospitals.
• Used in dialysis, and in pregnant women or after surgery to prevent deep vein thrombosis or thrombosis after myocardial infarction.

Summary

• The summary highlights the importance of knowledge of haemostasis, classification of bleeding disorders. and familiarity with medical conditions and drug therapies that affect the bleeding risks for patients.