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Perioperative Anticoagulation issues

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					  Perioperative
Coagulation Issues

     Michael E. Lazarus M.D.
     David Geffen School of Medicine
     at UCLA
     Division of General Internal
     Medicine.
Incidence of Fatal PE in
 Perioperative setting
• 0.1-0.8 % during elective general surgery.

• 2-3 % during elective hip replacement.

• 4-7 % of patients undergoing surgery for a
  fractured hip.
       Incidence of VTE
• Asymptomatic VTE 20-25% of patients after
  general surgery and 45-60% of patients post hip or
  knee surgery.
• Most studies use “surrogate outcome” of
  Asymptomatic VTE to power their data because of
  the low incidence of symptomatic VTE.
• Fewer than 1 in 8 AVTE’s progress to SVTE’s
• More valuable studies show reduction in hard end
  points such as reduction in SVTE and PE
         Evidence Driven
            Guidelines
• Assess risks of VTE and Bleeding
• Evidence based safety and efficacy data of
  available agents.
• Determine the optimal duration of
  prophylaxis
• Involve surgeons and internists (post
  operative care providers)
      Risk factors associated with
              thrombosis.
•     Acquired
1.    Age > 70
2.    Lupus AC/ SLE                •    Inherited.
3.    Ethnicity                    1.   AT III deficiency
4.    Trauma                       2.   Protein C and S deficiency
5.    Prior thrombus               3.   APC Deficiency
6.    Venous Stasis                4.   Homocysteinemia
7.    Malignancy
8.    Obesity
9.    Stroke and Immobility
10.   Heart Failure
11.   Nephrotic Syndrome
12.   COPD
13.   Inflammatory Bowel Disease
14.   Pregnancy
          Risk Categories
• Low ( Fatal PE < 0.001%)
     •   <40
     •   No risk factors
     •   General Anesthesia lasting < 30 mins.
     •   Minor operative procedures.


• Moderate ( Fatal PE 0.1-0.7%)
     • >40
     • General Anesthesia for > 30 mins
     • <2 of the previous risk factors.
          Risk Categories
• High Risk (Fatal PE-1-5%)
     •   > 40
     •   Surgery for Malignancy or Orthopedic procedure
     •   Surgery lasting > 30 mins.
     •   Inhibitor deficiency state or any other risk factor.
           Guidelines
• The Sixth ACCP Consensus Conference on
  Antithrombotic Therapy.

• Chest 2001;119(1 Suppl):132S-75S

• Non-pharmacologic and pharmacologic
  regimens
             Modalities
Non-pharmacologic        Pharmacologic
1. Early Ambulation      1. Low Dose
                             Unfractionated Heparin
2. Elastic Stockings     2. Aspirin
3. Intermittent          3. Warfarin
   Pneumatic             4. Low molecular weight
   Compression devices       heparin
4. IVC Filters           5. Direct thrombin
                             inhibitors
      Early Ambulation
• The earlier the better
• Lower incidence of SVTE, Shorter length of
  stay, earlier return to the community, fewer
  complications and lower 6 month mortality.
• Used with elastic stockings for low risk
  patients as only form of prophylaxis.
       Elastic stockings
• Improve venous flow and reduce vessel
  wall damage secondary to passive venous
  dilatation.
• Fit properly, above knee and continue use
  throughout hospitalization and rehab period.
• Not recommended as solo prophylaxis for
  moderate and high risk patients
     Intermittent pneumatic
      compression devices
• Exact mechanism whereby they prevent VTE is
  unclear.
• Reduce venous stasis.
• Promote the clearance of pro-thrombotic
  coagulation factors.
• Possibly increase local plasminogen activator
• Not as effective in patients with BMI > 25.
• Only effective when used continuously
• Not recommended as the primary agent in high
  risk patients and Hip and knee surgery.
    Intermittent pneumatic
     compression devices
• Reduce bleeding at surgical site possibly
  related to its effects on plasminogen

• No difference between IPC and LMWH for
  VTE prevention in gynecologic malignancy
  surgery
     • Obstet Gynecol 2001;98(6):989-995.
      Inferior Vena Cava
             Filters
•    Indications
    1. Absolute contraindication to anticoagualtion.
    2. Life threatening hemorrhage on
       anticoagulation.
    3. Failure of adequate anticoagulaion.
              IVC Filters
• Evidence: N Engl J Med 1998;338(7):409-
  15.
  – Controlled trial of IVC filters in patients with
    acute proximal DVT
  – Non significant reduction in the incidence of
    fatal pulmonary embolism.
  – Significant increase in the number of
    subsequent DVT’s
 Low Dose Unfractionated
        Heparin
• 5000 IU sq q8-12.
• Most general surgical procedures as well as
  high risk gynecologic and urologic surgery
• When compared with LMWH it is
  associated with a modest increase in
  bleeding and HIT.
                    Aspirin
• Should not be used as the sole prophylaxis
  measure in post surgical patients.
• PEP trial: Lancet 2000;355(9212):1295-302
   – 13 000 patients randomized to 160 mg ASA per day or
     placebo for 5 weeks.
   – All got routine thromboprophylaxis
   – Significant reduction in PE in ASA group 0.7 vs. 1.2%.
   – 58 % lower incidence of fatal PE in ASA group.
   – Increased bleeding incidence in the ASA group (not
     fatal)
              Warfarin
• Indicated for the very high risk surgical
  patient.
• Hip fracture repair, total hip arthroplasty
  and total knee arthroplasty.
• Benefit supported by numerous meta-
  analyses.
• Generally 5 mg dose is recommended pre-
  operatively and 2.5 mg for patients >75
 Low Molecular Weight Heparin

• Dalteparin, enoxaparin and tinzaparin are
  available in the USA.
• All act to inhibit Factor Xa
• None are approved in pregnancy, spinal
  cord injury, trauma with high risk of
  bleeding or neurosurgery.
• Lower incidence of bleeding when
  compared with LDUH.
• Indicated in THA an TKA prophylaxis as
  lower incidence of thromboses.
           Fondaparinux
• Low molecular weight pentasaccaride.
• Inhibits Factor Xa.
• Lower incidence of thromboembolism when
  compared to enoxaparin after THA, TKA, and
  Hip fracture surgery 12.5% vs. 27.8% but
  significantly no difference in the incidence of
  symptomatic VTE (0.5%)
• In the TKA study fondaparinux had a higher
  incidence of bleeding vs. enoxaparin
  Perioperative management of
  patients on long term oral AC

• Weigh the risk of thromboembolism against
  the risk of bleeding
• Who are most at risk if OAT is interrupted?
     •   Mechanical heart valves
     •   Atrial fibrillation
     •   Prior stroke or multiple risk factors
     •   Recent(<1 month) DVT
AC regimens for Chronic OAT patient
  undergoing non cardiac surgery
         Clinical Situation                 Anticoagulation regimen

Procedures associated with low        Continue OAT at usual dose or
bleeding risk (dental, cataract and   target INR to =2
dermatologic)
Aortic valve prosthesis and no         Stop OAT 4-5 days pre surgery,
additional risk factors or A. fib with operate when INR <1.5; resume
a low stroke risk                      daily dose of warfarin on the day of
                                       surgery
MV or AV with multiple risk           Stop OAT 3-5 days prior to surgery;
factors; recent VTE(<3 months);       start IV heparin when INR <2; stop
AF and high stroke risk               heparin 6 hrs prior to surgery;
                                      restart sq heparin and oral AC as
                                      soon as possible; Stop heparin
                                      when INR therapeutic for 2
                                      consecutive days.
             DVT Prophylaxis guidelines
Drug         Abdominal      Total Hip        Total Knee        Medical
             Surgery        Replacement      Replacement       Conditions
Unfract-       5000 U                                            5000 U
ionated       SC q8-12                                          SC q8-12
Heparin

Warfarin                      Start post       Start post      1 mg PO qd
                              operation        operation       for
                             Target INR       Target INR       indwelling
                                 2-3              2-3          catheters


Enoxaparin                                                     40 mg SC qd
                            30 mg SC         30 mg SC
             40 mg SC       q12h, 1st dose   q12h, 1st dose
             qd, 1st dose   12-24 h post     12-24 h post op
             1-2 hrs        op or 40 mg
             preop          SC qd starting
                            12h preop
       DVT Prophylaxis guide (Continued)
Drug       Abdominal        Total Hip            Total Knee    Medical
           Surgery          Replacement          Replacement   Conditions



Dalteparin 2500 IU SC       2500 IU SC q24h,
           q24h, preop      2h preop and 6h
           (Moderate        postop then 5000
           risk) or 5000    IU SC
           IU SC q24, 1st   q24(Moderate risk)
           dose q8-12h      or 5000 IU SC q8-
           preop (High      12h, then q24h
           risk Patients)   postop (High risk
                            Patients)
       DVT Prophylaxis guide (Continued)
Drug       Abdominal   Total Hip     Total Knee      Medical
           Surgery     Replacement   Replacement     Conditions




Fonda-                 2.5 mg SC 6 h 2.5 mg SC 6 h
parinux                postop, then  postop, then
                       2.5 mg SC qd 2.5 mg SC qd