Von Willebrand's Disease (vWD)
Considerations
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High risk for perioperative bleeding
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Sequelae of bleeding in enclosed spaces (joints, intracranial, pericardium, thorax)
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Potential contraindication to neuraxial anesthesia & analgesia
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Consultation with hematology for factor optimization (replacement/supplementation)
Goals
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Optimize factor activity & coagulation profile in perioperative period
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Techniques for minimizing perioperative blood loss
Optimization
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Consultation with hematologist for appropriate factor management
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Schedule OR early in the week & early in the day (ensure all lab/blood bank/consultant resources available)
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Assay factor levels 48h prior to OR & restore levels to 40% of normal prior to surgery, as dictated by the surgical procedure (see tables below). Key trough factor VIII levels:
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Obstetric > 50%
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Minor surgery > 30%
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Major surgery > 50%
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Repeat factor assay after initial administration to confirm factor activity (within 2 hours of expected OR start)
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Continue to monitor factor activity level intra-operatively as dictated by clinical situation
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Avoid all anti-platelet medications
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Consider antifibrinolytics during perioperative period (up to 3-5 days)
Management
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DDAVP 0.3 mcg/kg (provides 3-5 fold increase in activity); only if known responder:
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Maximum effect 30 min post dose but levels remain elevated for 6-8 hours
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DDAVP works by stimulating the release of vWF from endothelial cells
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Factor VIII-vWF concentrates (Humate P)
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Platelet concentrates (contains vWF)
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Recombinant factor VIII
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Recombinant factor VIIa
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Emergency: cryoprecipitate (contains vWF, FVIII, FXIII, fibronectin, fibrinogen)
Pregnancy
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Establish baseline factor VIII, vWF, ristocetin cofactor early in pregnancy & at 34 weeks
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During pregnancy, prophylactic treatment if factor VIII level < 25% (typically levels increase with pregnancy)
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Know the patient's type & factor VIII level:
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Responder: at labour onset, DDAVP 0.3mcg/kg IV q12h
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Non-responder: Humate P or cryoprecipitate
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Labour & delivery/cesarean section: maintain levels > 50% of normal
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Post-partum: follow levels & treat if < 25% or significant hemorrhage
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Regional: epidural safe if factor VIII & vWF > 50%
Treatment Choices Based on Sub-types
Recommended Dosages of Factor VIII for Patients with Severely Reduced (<10%) Factor Levels