1 Department of Anesthesiology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo 160-8582, Japan.
2 Department of Anesthesiology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo 160-8582, Japan. Electronic address: kosugi@z6.keio.jp.