A 75-year-old man arrives at the emergency department after passing three large-volume, melenic stools over a 2-hour period. Medical history is significant for atrial fibrillation and hypertension. Medications are warfarin, metoprolol, and lisinopril.

On physical examination, he is diaphoretic and the skin is cool to the touch. Temperature is 36.8 °C (98.2 °F), blood pressure is 82/64 mm Hg, pulse rate is 142/min and irregular, and respiration rate is 20/min. Oxygen saturation is 95% breathing ambient air. Cardiac examination reveals tachycardia. Pulmonary examination is normal. Peripheral pulses are thready. Rectal examination reveals melenic stool that is guaiac positive.

Laboratory studies:

Hemoglobin

8.2 g/dL (82 g/L); 12.8 g/dL (128 g/L) 3 months ago

Leukocyte count

8600/µL (8.6 × 109/L)

Platelet count

183,000/µL (183 × 109/L)

INR

7.4

In addition to intravenous vitamin K and fluid resuscitation, which of the following is the most appropriate treatment?