Pharm

Unfractionated Heparin

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Unfractionated Heparin, Heparin

  • Mechanism
  1. Potentiates Antithrombin III (AT III)
  2. See Intrinsic Clotting Pathway
  1. Heparin 5000 Units SQ every 8-12 hours
  • Dosing
  • Therapeutic Dosing by Weight based Calculations
  1. Measure
    1. Total body weight (TBW) in kilograms
    2. Height in inches
  2. Calculate Lean Body Weight (LBW) in kilograms
    1. Male: 50 + 2.3 x (height in inches - 60)
    2. Female: 45 + 2.3 x (height in inches -60)
  3. Calculate Dosing Weight
    1. Non-Obese
      1. Dosing Weight (kg): TBW above
    2. Obese (TBW > 1.4 x LBW)
      1. Dosing Weight (kg): (0.4 x TBW) + LBW
  4. Calculate Heparin starting doses
    1. Bolus: 80 Units/kg
      1. Maximum: 10,000 units
      2. Round to nearest 100 units
    2. Maintenance: 18 Units/kg/hour
      1. Round to nearest 50 units per hour
  • Labs
  • Therapeutic Dosing Initial (before Heparin)
  • Labs
  • Therapeutic Dosing Recurring Labs
  1. Partial Thromboplastin Time (aPTT)
    1. 6 hours after bolus and then per nomogram
  2. Platelets
    1. Every 3 days
    2. Minimum: 150,000
  • Protocol
  • Therapeutic Dosing Nomogram
  1. aPTT under 40
    1. Give 6000 unit bolus
    2. Increase maintenance rate by 6 units/kg/hour
    3. Recheck aPTT in 6 hours
  2. aPTT 40-49
    1. Give 3000 unit bolus
    2. Increase maintenance rate by 4 units/kg/hour
    3. Recheck aPTT in 6 hours
  3. aPTT 50-59
    1. Give 1500 unit bolus
    2. Increase maintenance rate by 2 units/kg/hour
    3. Recheck aPTT in 6 hours
  4. aPTT 60-85
    1. No change in dosing
    2. Recheck aPTT on the next morning
  5. aPTT 86-100
    1. Decrease maintenance rate by 1 unit/kg/hour
    2. Recheck aPTT in 6 hours
  6. aPTT over 100
    1. Stop Heparin for 60 minutes
    2. Decrease maintenance rate by 2 units/kg/hour
    3. Recheck aPTT in 6 hours
  • Adverse Effects
  1. Bleeding complications
  2. Heparin Induced Thrombocytopenia
  • Management
  • Reversal