Review Question - QID 109846

A 45-year-old woman presents to the emergency department with hematemesis. Her son said that the patient had complained of gnawing abdominal pain that worsened before and improved after meals for the past 3 weeks. She frequently travels for work and is often stressed. She drinks alcohol socially and does not smoke tobacco or marijuana. She has not had anything to eat or drink for the past 24 hours due to the pain, but coughed up "several cups of" frank red blood before arrival. Her temperature is 98°F (37°C), blood pressure is 80/50 mmHg, pulse is 140/min, respirations are 23/min, and oxygen saturation is 96% on room air. Gastric ultrasound reveals high gastric residual volume. The patient is empirically started on 3 units of uncrossmatched O-negative blood transfusion and pantoprazole. The patient's initial laboratory data return in the meantime:

Hemoglobin: 5 g/dL
Hematocrit: 18 %
Leukocyte count: 8,000/mm^3 with normal differential
Platelet count: 400,000/mm^3

Serum:
Na+: 140 mEq/L
Cl-: 115 mEq/L
K+: 3.2 mEq/L
HCO3-: 26 mEq/L
BUN: 60 mg/dL
Glucose: 104 mg/dL
Creatinine: 1.1 mg/dL

Blood type: AB
Rhesus status: negative

After bedside esophagogastroduodenoscopy with stapling of several peptic ulcers, repeat labs are obtained in 2 hours. The patient now complains of feeling hot with intermittent shivering. She denies any other symptoms. Her temperature is 101°F (38.3°C), blood pressure is 100/55 mmHg, pulse is 100/min, respirations are 20/min, and oxygen saturation is 99% on room air. Her lungs are clear to auscultation bilaterally, and no accessory respiratory muscle use is observed. No rash is seen. What is the most likely diagnosis?