Perioperative Management of Oral Anticoagulation by Ua7WLhH

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									Perioperative Management of
    Oral Anticoagulation

         Ri 陳信宏
                        References
   Perioperative Management of Oral Anticoagulation
    Clinics Geriatric Medicine 22 (2006) 199– 213
   Perioperative bridging therapy for the at-risk patient on
    chronic anticoagulation
    Disease-A-Month 01-FEB-2005; 51(2-3): 183-93
               Introduction(1)
   OAC therapy during surgery is associated with
    increased excessive operative bleeding.
   Patients receiving long-term oral anticoagulant
    (OAC) therapy that requires temporary
    discontinuation for an elective surgical or
    invasive procedure.
   Anticoagulation cessation, -increased risk of
    thromboembolism, especially in the
    postoperative period.
                Introduction(2)
   A management strategy for the at-risk patient on
    chronic OAC requiring temporary discontinuation for
    an elective surgical or invasive procedure.
   Emphasis on the indications for use of perioperative
    bridging therapy.
   The use of parenteral, short-acting anticoagulants
    such as unfractionated heparin (UFH) or low-
    molecular-weight-heparin (LMWH) in the
    perioperative period.
Thromboembolic and Bleeding Risks
    in the Perioperative Period
 Thromboembolic risks:
(1)Disease specific thromboembolic risks when
  discontinuing warfarin
(2)Hypercoagulability associated with surgery.
 Bleeding risks:

(1) the patient
(2) the use of anticoagulant therapy
(3) the surgery or procedure
       Thromboembolic Risk When
         Discontinuing Warfarin
Venous thromboembolism (VTE):
 The absence of OAC during the first month of an
  acute VTE event-Recurrence 40%/month
 During the second and third month- Recurrence
  10%/2month
 After the 3 month treatment-15%/year

 Surgery should be deferred following an acute
  episode of venous thromboembolism until patients
  have received at least 1 month, and preferably 3
  months,of anticoagulation.
         Venous thromboembolism
   Surgery is performed within 1 month of an
    acute event, bridging therapy should be used
     while the INR is less than 2.
   Within 1 and 3 months previously, patients are
    immobilized-bridging therapy
   Treated with 3 or more months of
    anticoagulation-not use bridging therapy.
       Arterial thromboembolism
Nonvalvular atrial fibrillation (NVAF):
 Average risk of systemic embolism -
  4.5%/year in the absence of OAC.
 The CHADS2 Score(estimate expected stroke
  rate per 100 patient-years):
 Moderate-risk patients have an adjusted stroke
  rate of up to 5.9%
 High-risk patients have adjusted stroke rates

  of 8.5 to 18.2%.
       Arterial thromboembolism
Mechanical prosthetic cardiac valves (MHV)
 In the absence of OAC, mitral position valve
  prostheses have an annualized thrombosis risk
  of 22% compared with an annualized risk of
  approximately 10 to 12% for aortic position
  valves.
 The average rate of major thromboembolism in
  non-anticoagulated patients with mechanical
  heart valves is estimated to be 8%.
        Previous thromboembolism
   The single most important risk factor for
    ischemic stroke in patients with atrial
    fibrillation
   Also an important risk factor in patients with
    prosthetic heart valve.
    Hypercoagulability associated with
                surgery
   Prothrombotic effect of major surgery and
    laparoscopic procedures-theoretically
    increase the postoperative VTE risk 100-fold.
   A recent systematic review revealed a 10-fold
    greater risk of stroke than expected in patients
    not receiving perioperative anticoagulation.
                   Bleeding Risks
Patient:
 Previous history of bleeding, especially with invasive
  procedures or trauma
 Use of concomitant antiplatelet and nonsteroidal
  antiinflammatory medications.
Procedure:
 High :include major operations and procedures (lasting >45
  minutes)
 Low : include non-major operations and procedures (lasting
  <45 minutes)
Perioperative anticoagulants:
 2-day period : 2 to 4% for major surgery
                 0 to 2% for non-major surgery.
Thromboembolic risk when discontinuing OAC
Procedural Bleeding Risks
             Clinical consequences
   MHV thrombosis is fatal in 15% of patients
   ATE: mortality -about 40% of events
          major disability -about 20% of events
   VTE : mortality -approximately 6%
          major disability -approximately 5% or less
                             in treated patients.
   Postoperative major bleeding has a fatality rate of
    approximately 3%.
 Perioperative Management Recommendations

The Seventh American College of Chest Physician
   Consensus Conference:
 Intermediate risk of thromboembolism-prophylactic
   (or higher) dose UFH or LMWH as perioperative
   bridging therapy
 High risk of thromboembolism-

  full-dose UFH or LMWH
 Low risk of bleeding-

   Continue warfarin therapy at a lower dose to maintain
   an INR of 1.3 to 1.5.
      Perioperative bridging algorithm
   Low risk of ATE or VTE:
    No heparin bridging preoperatively and only
    prophylactic doses of LMWH or UFH
    postoperatively in conjunction with resumption
    of warfarin.
                   Warfarin
   INR starts to fall at approximately 29 hours
    after the last dose of warfarin
   A half-life of approximately 22 hours
   It is reasonable to start bridging therapy
    approximately 60 hours after the last dose of
    warfarin.
  Unfractionated heparin (UFH)
Advantage:
 A short half-life(60 minutes)

 easily reversed (by protamine sulfate)

Disadvantage:
 Intravenous administration necessitates

  hospitalization before surgery,
 Inconvenient and expensive.
       Low-molecular-weight-heparin
               (LMWH)
   Allowed bridging therapy to be administered
    to outpatients.
   Doses of LMWH that are recommended for
    treatment of venous thromboembolism are
    administered once or twice daily, generally for
    3 days before surgery.
   Required to determine whether the benefit of
     bridging therapy outweighs the associated
    risks of bleeding.
       Perioperative bridging protocol
Instructions regarding warfarin use:
   1. Stop warfarin at least 4 days prior to surgery
   2. Check INR 1 day prior to surgery
       If 1.5, proceed with surgery
       If 1.5 to 1.8, consider low-level reversal with Vitamin K
       If 1.8, recommend reversal with Vitamin K (either 1 mg SC
       or 2.5 mg PO)
   3. Recheck INR day of surgery
   4. Restart maintenance dose of warfarin the evening of surgery
   5. Daily INR until in therapeutic range (1.9)
        Perioperative bridging protocol
Instructions regarding IV UFH use
   1. Should start at least 2 days prior to surgery at therapeutic
      dose using a validated, aPTT-adjusted, weight-based
      nomogram (ie, 80 U/kg bolus dose IV followed by a
      maintenance dose of 18 U/kg/h IV)
   2. Discontinue 6 hours prior to surgery
   3. Restart no less than 12 hours postoperatively at the previous
       maintenance dose once hemostasis is achieved
   4. Discontinue IV UFH when INR is in therapeutic range (1.9)
        Perioperative bridging protocol
Instructions regarding LMWH use:
   1. Should start at least 2 days prior to surgery at BID
       therapeutic dose (ie, enoxaparin 1 mg/kg SC BID or
       dalteparin 100 IU/kg SQ BID)
   2. Discontinue at least 12 hours prior to surgery (if surgery is
       in early A.M. consider holding previous evening dose)
   3. Restart usual therapeutic dose within 12–24 hours after
       surgery once hemostasis is achieved
   4. Discontinue LMWH when INR in therapeutic range (1.9)
                     Summary
   OAC should be discontinued at least 4 days prior to
    the surgical intervention or procedure
   Heparin (either UFH or LMWH) initiated at least 2
    days prior to the intervention.
   Many experts-advocate preoperative therapeutic-dose
    UFH or LMWH for intermediate- to high-risk
    patients
   Considerable disagreement -prophylactic dose,
    treatment dose, or no heparin bridging therapy should
    be initiated postoperatively in conjunction with
    resumption of OAC
                  Summary
   OAC should be resumed at the usual
    maintenance dose within 24 hours of the
    procedure, preferably the same evening.
   Heparin should be reinitiated within 24 hours
    of the procedure, provided that adequate
    hemostasis is achieved, and discontinued once
    the INR is in therapeutic range (1.9).
Thanks for your attentions !

								
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