1. Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama , Japan
2. Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama , Japan
3. Center for Innovative Clinical Medicine, Okayama University Hospital , Okayama , Japan