1. Department of Anesthesiology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo, Kyoto 602-8566, Japan
2. Department of Anesthesiology, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan
3. Division of Critical Care, Kyoto Prefectural University of Medicine Hospital, 465 Kajii-cho, Kamigyo, Kyoto 602-8566, Japan