A 34-year-old woman presents to the emergency department with a chief complaint of acute onset of shortness of breath. It started with a right-sided chest pain an hour ago. She denies fever, chills, cough, vomitings and diarrhea. She also has right lower extremity swelling that started two days ago, when she returned from Honolulu, Hawaii to State College, Pennsylvania traveling in long flights. The family history is notable for a father who died of an embolic stroke. She smokes one pack of cigarettes a day and uses oral contraceptives for birth control. On physical examination, she appears anxious and in respiratory distress. Her temperature is 99 °F (37.2 °C), heart rate is 108 beats/min, blood pressure is 165/105 mm Hg, respirations are 34 breaths/min, and oxygen saturation is 94% on room air. Chest x-ray film is normal. Ventilation-perfusion scan revealed a high probability of pulmonary embolism. She was initiated on heparin for anticoagulation. She requested early discharge from the hospital because of a family emergency and was transitioned to warfarin 5 mg once daily. Three days later, she developed pain and redness on her legs followed by a skin rash with large, irregular bullae with sharp red borders. Later, the skin necrosed and formed an eschar. Of the following, what is the next best step in the management of this patient?
