Kentaro Shimizu1, Hiroshi Ogura2. 1. Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Japan. Electronic address: shimiken@hp-emerg.med.osaka-u.ac.jp. 2. Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Japan. Electronic address: ogura@hp-emerg.med.osaka-u.ac.jp.