1. Department of Emergency and Critical Care Medicine, Graduate School of Medicine, University of the Ryukyus, 207, Uehara, Nishihara-cho, Okinawa 903-0215, Japan
2. Department of Emergency Medicine, Center for Resuscitation Science, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
3. Division of Acute Care Surgery, Trauma, and Surgical Critical Care, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
4. Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
5. Department of Emergency and Critical Care Medicine, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan