Review Question - QID 215161

A 67-year-old woman presents to the emergency department with a headache. She was lifting weights when the headache suddenly developed. Although she occasionally has migraines, she describes her current headache as the worst of all her headaches. There is associated nausea and vomiting. Her medical history includes hypertension, hyperlipidemia, and atrial fibrillation. Her medications are chlorthalidone, atorvastatin, acetaminophen, and warfarin. She smokes 1 pack of cigarettes per day and has a 50-pack-year smoking history. Her temperature is 99.2°F (37.3°C), blood pressure is 144/92 mmHg, pulse is 50/min, and respirations are 8/min. On exam, the patient is lethargic and there is limited passive neck flexion. Laboratory results are below:

Activated partial thromboplastin time (aPTT): 35 seconds
Prothrombin time (PT): 51 seconds
International normalized ratio (INR): 4.2

After the diagnosis is confirmed, which of the following is the most appropriate next step in management for the reversal of anticoagulation?