Bleeding Disorders for Dental Hygienists

Bleeding Disorders (Part 1)

• The session aims to describe bleeding disorders for dental hygienists and therapists.
• GDC learning outcomes include explaining general and systemic diseases, their relevance to oral health, and describing and applying relevant physiology to patient management.
• Recognizing abnormalities of the oral cavity and the rest of the patient, and raising concerns where appropriate is crucial.
• Identifying where patients' needs differ from the treatment plan and referring them accordingly is also emphasized.

Haemostasis

• Haemostasis is the physiological response preventing significant blood loss after vascular injury.
• The process involves three key events:
  • Vascular system - injured vessels constrict.
  • Platelet system - platelet activation and aggregation to form a plug.
  • Coagulation cascade - activation to produce a fibrin plug.

Aggregation of Platelets

• Platelet activation involves three stages:
  • Adhesion: platelets stick to damaged blood vessels.
  • Secretion: platelets release substances.
  • Aggregation: platelets clump together.

The Coagulation Cascade

• This cascade involves a complex series of reactions resulting in the formation of a fibrin clot.
• Two main pathways exist:
  • Intrinsic pathway - initiated by activation of clotting factors within the blood.
  • Extrinsic pathway - initiated by tissue damage, leading to activation of clotting factors in the surrounding tissue.
  • Final common pathway - where both pathways converge and ultimately result in the formation of a fibrin clot

Classification of Bleeding Disorders

• Bleeding disorders are categorized into:
  • Disorders of blood vessels.
  • Disorders of platelets.
  • Disorders of coagulation.

Disorders of Blood Vessels

• Inherited disorders:
  • Connective tissue disorders e.g., Ehlers Danlos syndrome
  • Hereditary hemorrhagic telangiectasia (HHT).
• Acquired disorders:
  • Severe infections (e.g., meningococcal, typhoid).
  • Medications (e.g., sulphonamides).
  • Vitamin C deficiency, senile purpura.

Disorders of Platelets

• Thrombocytopenia: a reduced platelet count (below 150 x 109/L). Causes:
  • Decreased/failure of platelet production.
  • Destruction of circulating platelets.
  • Disorders of platelet function.
• Idiopathic thrombocytopenic purpura (ITP): a rare autoimmune blood disorder affecting platelets. Two Forms:
  • Acute ITP - often following viral infections in children.
  • Chronic ITP - can occur at any age and symptoms can persist for months or years.

Disorders of Coagulation

• Inherited:
  • Haemophilia A - deficiency in Factor VIII.
  • Haemophilia B - deficiency in Factor IX.
  • Von Willebrand Disease - deficiency in von Willebrand Factor.
• Acquired:
  • Liver disease - reduced production of clotting factors.
  • Haematological malignancies - impaired coagulation.
  • Anticoagulant drugs.

Antiplatelet and Anticoagulant Drugs

• Antiplatelet drugs are used to prevent blood clot formation in situations like ischemic heart disease and previous myocardial infarction. Aspirin, Clopidogrel, Dipyridamole, Ticagrelor, and Prasugrel are examples.
• Anticoagulant drugs prevent blood clotting, and are used in conditions such as stroke, deep vein thrombosis, and pulmonary embolism. Warfarin, direct oral anticoagulants (DOACs), and Heparin are example drug classes.

Warfarin

• A vitamin K antagonist that blocks enzymes needed to produce clotting factors.
• Monitored using INR (international normalized ratio).

Direct Oral Anticoagulants (DOACs)

• Rivaroxaban, Apixaban, Edoxaban inhibit Factor Xa.
• Dabigatran directly inhibits thrombin.
• Generally have a faster onset of action and fewer drug interactions compared to Warfarin.

Heparin

• Short half-life, primarily used intravenously.
• Used to prevent thrombosis in various situations such as after surgery, heart attack, and during dialysis.