1. Department of Anesthesia, Hualien Tzuchi Hospital, Hualien 97002, Taiwan
2. Department of Surgery, Hualien Tzu-Chi Hospital, Buddhist Tzu Chi Medical Foundation and School of Medicine, Tzu-Chi University, Hualien 97002, Taiwan
3. Department of Otolaryngology, Hualien Tzu Chi Hospital, No. 707, Sec. 3, Chung-Yang Road, Hualien 97002, Taiwan
4. Laboratory of Bio-Math, Department of Financial Engineering, Providence University, 200, Sec. 7, Taiwan Boulevard, Shalu Dist., Taichung City 43301, Taiwan
5. Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115, USA