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A 47-year-old female with protein S deficiency presents to the emergency department with acute cholecystitis and is admitted to the hospital. She currently takes warfarin (Coumadin), 5 mg daily, and has a previous history of deep-vein thrombosis and two pulmonary embolisms. Her last pulmonary embolism was 5 years ago. The surgeon consults you about perioperative management of the patient’s anticoagulation. He plans to perform a laparoscopic cholecystectomy tomorrow morning. The patient’s INR on admission was 2.9. Which of the following would be appropriate recommendations? (Mark all that are
true.)
○ Administration of vitamin K, 2.5 mg orally tonight
○ Administration of a dose of vitamin K 90 minutes before surgery if the patient’s INR is ≥1.9 at that time
○ Bridge therapy with a therapeutic dose of low molecular weight heparin after the surgery
○ Continued hospitalization postoperatively until the INR is therapeutic
○ Restarting warfarin at the patient’s usual dosage tomorrow evening
A, C, E
This patient’s INR should be normalized by the morning of the surgery, so vitamin K the evening before would be appropriate (SOR C). If her INR had not normalized by the morning of the surgery, she should receive low-dose oral vitamin K plus either fresh frozen plasma or another prothrombin concentrate. The patient is considered at high risk for recurrent venous thromboemoblism because of her protein S deficiency, and bridge therapy with low molecular weight heparin (LMWH) or intravenous unfractionated heparin is recommended, starting 24–72 hours after surgery (SOR C). From a cost-containment perspective, the best choice is subcutaneous LMWH administered in an outpatient setting if this is feasible (SOR B/C).
When resuming vitamin K antagonists after surgery, approximately 48 hours is required to attain a partial anticoagulant effect, with an INR >1.5. Consequently, the potential effect of these agents to promote postoperative bleeding is likely to be mitigated by the delayed onset of their anticoagulant activity. It is reasonable, therefore, to resume warfarin therapy on the evening of the day of surgery or the next day, with a partial anticoagulant effect anticipated to occur 48 hours later (SOR C).