Current Insights On Perioperative Management Of Anticoagulation Therapy

Increasingly, the podiatric physician must perform surgery on patients receiving anticoagulant therapy. Decisions on the perioperative management of anticoagulation represent a balance among concerns regarding postoperative hematoma, excessive bleeding and patient safety with consideration of the reasons why the patient started on anticoagulant therapy.

No organization has proposed specific guidelines directed toward foot and ankle surgery. However, the American College of Chest Physicians has proposed evidence-based clinical practice guidelines for the perioperative management of antithrombotic therapy.1 In light of the introduction of new anticoagulation therapy utilized today and alterations in the use of previously approved anticoagulant therapy, the following represents a summary of the recommendations regarding antithrombotic therapy in the perioperative period.

Vitamin K antagonist therapy. In patients receiving vitamin K antagonists such as warfarin (Coumadin, Bristol-Myers Squibb), the recommendations are stopping the vitamin K antagonists five days prior to surgery rather than for a shorter period of time before surgery.1 When surgery has interrupted vitamin K antagonist therapy, the recommendation is restoration of the vitamin K antagonist therapy between 12 and 24 hours following surgery.

In a high-risk patient who has a mechanical heart valve, atrial fibrillation or history of venous thromboembolism, the guidelines recommend bridging therapy during the time of vitamin K antagonist interruption. One may utilize agents such as heparin, enoxaparin (Lovenox, Sanofi) or similar agents as bridging therapy. Conversely, patients with mechanical heart valves, atrial fibrillation or venous thromboembolism who are considered low risk do not require bridging therapy during the period of interruption of vitamin K antagonist therapy.

For minor dermatologic surgical procedures, the suggestion is that the patient continue on vitamin K antagonist therapy in the perioperative period and that the physician make efforts to optimize local hemostasis.

Aspirin therapy. For patients undergoing minor dermatologic procedures, the guidelines say patients may continue taking aspirin for the prevention of cardiovascular disease throughout the perioperative period.1 Rather than discontinue aspirin use seven to 10 days before the procedure, patients undergoing other procedures who are considered at moderate to high risk for cardiovascular events should continue on aspirin through the perioperative period.

Patients with stent placement. In patients with a heart stent who are also receiving dual antiplatelet therapy, the guidelines recommend postponing surgery for at least six weeks following the placement of a bare metal stent and for six months after placement of a drug-eluting stent.1 Patients who require urgent surgery within six weeks of placement of a bare metal stent or within six months of placement of a drug-eluting stent should continue dual antiplatelet therapy in the perioperative period rather than stopping it seven to 10 days before surgery.

Bridging therapy. Bridging therapy is generally defined as the administration of a short-acting anticoagulant for approximately 12 days to compensate for the interruption of vitamin K antagonist therapy until an international normalized ratio (INR) returns to normal therapeutic range.

The guidelines recommend that patients who are receiving bridging therapy with unfractionated heparin discontinue the heparin four to six hours prior to surgery rather than at a closer time to the surgical procedure.1 Patients who are receiving bridging anticoagulation with low molecular weight heparin should have their last preoperative dose of the low molecular weight heparin 24 hours before surgery rather than 12 hours prior to surgery. If a patient is receiving bridging into coagulation with a therapeutic dose of low molecular weight heparin and is to undergo a surgery with a high bleeding risk, the low molecular weight heparin efforts should start again 48 to 72 hours after surgery rather than within 24 hours of surgery

Antiplatelet therapy. Aspirin, clopidogrel (Plavix, Bristol-Myers Squibb), ticlopidine (Ticlid, Roche) and prasugrel (Effient, Eli Lilly) are drugs that all irreversibly inhibit platelet function. Use of antiplatelet therapy for up to 10 days is required to replenish a normal platelet pool. Other antiplatelet drugs may irreversibly inhibit platelet function with self-limited effects dependent upon the half-lives of the medications. This would include drugs such as paclitaxel (Taxol, Bristol-Myers Squibb), nonsteroidal anti-inflammatory medications (NSAIDs) and dipyridamole (Persantine, Boehringer Ingelheim).

Preoperative protocols. The guidelines suggest that some protocols may be helpful for the standardization of perioperative management for inpatients on anticoagulant therapy to prevent thromboembolic disease as well as bleeding complications.1 This protocol includes the following:

1. Assess the patient at least seven days prior to surgery in order to allow the planning of perioperative anticoagulation prior to surgery.
2. Provide the patient with a calendar outlining the perioperative timing of warfarin and antiplatelet drug discontinuation and resumption, as well as dose and timing of bridging therapy.
3. Perform international normalized ratio testing on the day before surgery to identify patients with continued elevation of international normalized ratio in order to allow timely correction with the use of oral vitamin K or deferral of the surgical procedure when possible.
4. Assess postoperative hemostasis on the day of surgery and on the first postoperative day in order to assess the ability to safely resume the use of anticoagulant drugs.
5. Ensure that the patient or caregiver received adequate education for injection techniques when utilizing outpatient low molecular weight heparin bridging therapy.
6. Consider the pharmacokinetic profiles of the patient’s current medications as well as his or her thromboembolic and bleeding risks in decision-making regarding perioperative anticoagulation therapy.

Reference

1. Douketis JD, Spyropoulos AC, Spencer FA, et al. Perioperative management of antithrombotic therapy: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012; 141(2 Suppl):e326S-50S.



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