1. Department of Anesthesia, Hualien Tzuchi Hospital, Hualien 97002, Taiwan
2. Bio-Math Laboratory, Department of Financial Engineering, Providence University, Taichung 43301, Taiwan
3. Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
4. Division of Otolaryngology-Head and Neck Surgery, LifeBridge Sinai Hospital, Baltimore, MD 21218, USA
5. Division of Otolaryngology-Head and Neck Surgery, MedStar Union Memorial Hospital, Baltimore, MD 21218, USA