Perioperative Management of Oral Anti Coagulation

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Perioperative Management of

Oral Anticoagulation

RiRi


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ReferencesReferences

Perioperative Management of Oral Anticoagulation

Clinics Geriatric Medicine 22 (2006) 199 213

Perioperative bridging therapy for the at-risk patient on

chronic anticoagulationDiseaseDisease--AA--Month 01Month 01--FEBFEB--2005; 51(22005; 51(2--3): 1833): 183--9393


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Introduction(1)Introduction(1)

OAC therapy during surgery is associated withincreased excessive operativebleeding.

Patients receiving long-term oral anticoagulant(OAC) therapy that requires temporarydiscontinuation for an elective surgical orinvasive procedure.

Anticoagulation cessation,

increased risk ofthromboembolism, especially in thepostoperative period.


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Introduction(2)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.


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Thromboembolic and Bleeding Risks

in th

e Perioperative Period Thromboembolic risks:

(1)Disease specific thromboembolic risks whendiscontinuing warfarin

(2)Hypercoagulability associated with surgery.

Bleeding risks:

(1) the patient

(2) the use of anticoagulant therapy

(3) the surgery or procedure


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Thromboembolic Risk When

Discontinuing WarfarinVenous thromboembolism (VTE):

The absence of OAC during the first month of anacuteVTE eventRecurrence 40%/month

During the second and third month

Recurrence10%/2month

After the 3 month treatment15%/year

Surgery should be deferred following an acute

episode of venous thromboembolism until patientshave received at least 1 month, and preferably 3months,of anticoagulation.


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Arterial thromboembolism

Nonvalvular atrial fibrillation (NVAF):

Average risk of systemic embolism4.5%/yearin the absence of OAC.

The CHADS2 Score(estimate expected strokerate 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%.


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Arterial thromboembolism

Mechanical prosthetic cardiac valves (MHV)

In the absence of OAC, mitral position valveprostheses have an annualized thrombosis riskof22% compared with an annualized risk ofapproximately 10 to 12% foraortic positionvalves.

The average rate of major thromboembolism innon-anticoagulated patients with mechanicalheart valves is estimated to be 8%.


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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.


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Hypercoagulability associated with

surgery Prothrombotic effect ofmajor surgery and

laparoscopic procedurestheoretically

increase the postoperative VTE risk 100-fold.

A recent systematic review revealed a 10-fold

greater risk ofstroke than expected in patients

not receiving perioperative anticoagulation.


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Bleeding Risks

Patient:

Previous history of bleeding, especially with invasiveprocedures or trauma

Use of concomitant antiplatelet and nonsteroidal

antiinflammatory medications.Procedure:

High :include major operations and procedures (lasting >45minutes)

Low : include non-major operations and procedures (lasting


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Thromboembolic risk when discontinuing OAC


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Procedural Bleeding Risks


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Clinical consequences

MHV thrombosis is fatal in 15% of patients

ATE: mortalityabout 40% of events

major disabilityabout 20% of events

VTE : mortalityapproximately 6%

major disabilityapproximately 5% or less

in treated patients.

Postoperative major bleeding has a fatality rate of

approximately 3%.


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Perioperative Management Recommendations

The Seventh American College of Chest PhysicianConsensus Conference:

Intermediate riskof thromboembolismprophylactic

(or higher) dose UFH or LMWH as perioperativebridging therapy

High riskof thromboembolism

full-dose UFH or LMWH

Low risk of bleeding

Continue warfarin therapy at a lower dose to maintainan INR of 1.3 to 1.5.


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Perioperative bridging algorithm

Low risk of ATE orVTE:

No heparin bridging preoperatively and only

prophylactic doses of LMWH or UFHpostoperatively in conjunction with resumption

of warfarin.


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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.


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Unfractionated heparin (UFH)

Advantage:

A short half-life(60 minutes)

easily reversed (by protamine sulfate)Disadvantage:Disadvantage:

Intravenous administration necessitates

hospitalization before surgery, Inconvenient and expensive.


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Low-molecular-weight-heparin

(LMWH)

Allowed bridging therapy to be administeredto outpatients.

Doses of LMWH that are recommended fortreatment of venous thromboembolism areadministered once or twice daily, generally for3 days before surgery.

Required to determine whether the benefit ofbridging therapy outweighs the associatedrisks of bleeding.


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Perioperative bridging protocol

Instructions regarding warfarin use:

1. Stop warfarin at least 4 daysprior to surgery

2. Check INR 1 day prior to surgery

If 1.5, proceed with surgeryIf 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)


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Instructions regarding IV UFH use

1. Should start at least 2 daysprior 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 hoursprior to surgery

3. Restart no less than 12 hourspostoperatively at the previous

maintenance dose once hemostasis is achieved

4. Discontinue IV UFH when INR is in therapeutic range (1.9)


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Instructions regarding LMWH use:

1. Should start at least 2 daysprior 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 hoursprior to surgery (if surgery is

in early A.M. consider holding previous evening dose)

3. Restart usual therapeutic dose within 1224 hours after

surgery once hemostasis is achieved 4. Discontinue LMWH when INR in therapeutic range (1.9)


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SummarySummary

OAC should be discontinued at least 4 daysprior tothe surgical intervention or procedure

Heparin (either UFH or LMWH) initiated at least 2daysprior to the intervention.

Many experts-advocate preoperative therapeutic-doseUFH or LMWH forintermediate- to high-riskpatients

Considerable disagreementprophylactic dose,

treatment dose, or no heparin bridging therapy shouldbe initiated postoperatively in conjunction withresumption of OAC


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SummarySummary

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).


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Perioperative Management of Oral Anti Coagulation

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