1. Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
2. Division of Anesthesiology, Koujinkai Daiichi Hospital, Tokyo 125-0041, Japan
3. Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo 113-8421, Japan
4. Department of Anesthesiology, Cancer Institute Hospital, Tokyo 135-8550, Japan
5. Department of Anesthesiology, East Hokkaido Hospital, Kushiro 085-0036, Japan