Perioperative anticoagulation

Perioperative bleeding risk is classified into 2 groups: High risk with a 2 day risk of major bleeding of 2-4% or low risk with a 2 day risk of major bleeding of 0-2%.

Cardiovascular, vascular, oncologic, and urologic surgeries are associated with a high risk of bleeding.

Procedures associated with a low risk of bleeding include cholecystectomy, abdominal hysterectomy, hernia repairs, most laparoscopic surgeries, coronary angiography, and bronchoscopy.

Often not necessary to stop NOACs (novel oral anticoagulants) or warfarin for surgical procedures with moderate risk for bleeding, such as oral surgery or pacemaker implantation.

Many dental, dermatologic, and ophthalmologic surgical procedures are considered to have a low bleeding risk.

Patients receiving anticoagulation can have tooth extractions, endodontic, and minor reconstructive surgery, often times, without altering their anticoagulation treatment by using local hemostatic agents.

These agents include oxidized cellulose or an oral tranexamic acid mouthwash.

In patients undergoing minor dermatologic procedures, self-limited minor bleeding episodes occur with the continued use of warfarin, but the incidence of major bleeding less than 5%.

In patients undergoing ophthalmological procedures and who continue warfarin, some patients experience self-limited episodes of bleeding without compromising visual abilities.

For patients receiving spinal epidural anesthetic administration optimal coagulation studies should be achieved at the time of neuraxial anesthesia

For warfarin patients need to stop your treatment for approximately 5 days before surgery to remove any effects of the drug.

Warfarin has a 36-42 hour elimination half life, and with first-order pharmacokinetics each half-life correlates to an approximately 50% reduction in the anticoagulant effect.

With warfarin one half life decreases anticoagulation effect by approximately 50%, the second half-the life by 25%, the third half-life 12-1/2%, the fourth half-life by 6.25% and a fifth half-life by 3.125%.

For patients who require temporary interruption of warfarin for surgery, resuming warfarin on the evening of surgery or the day after is safe.

The use of low molecular weight heparin or UFH are effective when used in bridging therapy to prevent VTE.

When using bridging anticoagulation with UFH intravenously that agent should be stopped for-6 hours prior to surgery.

UFH intravenous bridging therapy is a safer choice for patients with severe renal insufficiency, or those on dialysis, compared to low molecular weight heparin.

UFH intravenously can be restarted postoperatively at the same infusion rate as before the procedure.

For the bridging use of subcutaneous LMWH the last preoperative dose should be approximately 24 hours prior to surgical procedure.

When using LMWH bridging therapy postoperative hemostasis must be assessed and reinstitution of treatment delayed until adequate surgical hemostasis has been assured as the anticoagulant effect is greatest closest to the time of surgery.

LMWH in low-bleeding risk situations can be restarted within 24 hours of surgical procedure, whereas in higher-bleed-risk situations reinitiation of anticoagulation with therapeutic doses of L LMWH should not be restarted before at 48-72 hours.

For targeted oral anticoagulants, novel oral anticoagluants (NOACs), perioperative management is determined by elimination half-life of the agents being utilized, the patient’s renal function, the risk of hemorrhage with the planned surgery.

Postoperative reinstitution of NOACs is based on the fact these agents have a rapid onset of action, potential effect of postoperative bowel impaired motility, and the use of acid suppressive therapy on the absorption of these agents.

Dabigatran (Pradaxa) has an elimination half life of 14-10 hours with normal or mildly impaired renal function.

In patients undergoing a surgical procedure with a high risk of bleeding, the last dose of dabigatran should be given 3 days before surgery.

In patients with moderate renal impairment, dabigatran has a half-life of 16-18 hours in the last those should be given 5 days before surgery.

For rivaroxaban (Xarelto) the half life is 8-9 hours and it’s renal clearance is 33%.

For Rivaroxaban, the drug should be stopped at least 3-4 days prior to surgical procedures with a high bleeding risk, and 2-3 days for low bleeding risk procedures.

For Rivaroxaban, in a patient with renal impairment, perioperative management should be stopping the drug four days prior to planned surgery.

For apixaban (Eliquis) the half life is 7-8 hours and the renal clearance is 25%.

For apixaban (Eliquis), the drug should be stopped at least 3-4 days prior to surgical procedures with a high bleeding risk, and 2-3 days for patients with low bleeding risk procedures.

For reintroduction of postoperative NOACs management should be based on bleeding risk and whether hemostasis has been achieved.

In patients undergoing major surgery re-institution of NOACs using lower doses for 2-3 days may be a safer option.

Patients with active cancer are considered at moderate risk for perioperative thromboembolism, which implies an annual risk of arterial thromboembolism of 5-10%, and a one-month venous thromboembolism risk of 2-10%.

Patients with advanced cancer, adenocarcinomas, high risk biomarkers, those who have experienced a recent thrombotic event, those with thrombophilia such as protein C, protein S, antithrombin deficiency, or antiphospholipid antibodies are at high risk for perioperative thromboembolism with an annual arterial thromboembolism risk of greater than 10% or one-month venous thromboembolism risk of greater than 10%.

In a trial of patients with atrial fibrillation who stopped taking warfarin before elective surgery or an invasive procedure, forgoing bridging anticoagulation was noninferior to perioperative bridging with low-molecular-weight heparin to prevent arterial thromboembolism(Douketis JD et al).

In the above study bridging nearly tripled the risk of major bleeding without providing benefits in preventing myocardial infarction, venous thromboembolism, or death when compared with no bridging.

The above study suggests that the risk of arterial thromboembolism in patients with atrial fibrillation who temporarily stop warfarin may have been over stated.

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