Chen-Hwan Cherng1, Yi-Hsuan Huang1, Ming-Lang Shih2. 1. Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center, Neihu 114, Taipei, Taiwan. 2. Department of Surgery, Tri-Service General Hospital and National Defense Medical Center, Neihu 114, Taipei, Taiwan. Electronic address: cherng1018@yahoo.com.tw.