1. Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
2. Department of Anesthesiology and Pain Medicine, College of Medicine, Seoul National University, Seoul, South Korea
3. Department of Emergency Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
4. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea