Vivian H Y Ip1, Rakesh V Sondekoppam2, Ban C H Tsui3. 1. Department of Anesthesiology and Pain Medicine, University of Alberta Hospital, Edmonton, AB, Canada. hip@ualberta.ca. 2. Department of Anesthesiology, University of Iowa, Iowa City, IA, USA. 3. Department of Anesthesiology, Perioperative Medicine and Pain Medicine, Stanford University, Stanford, CA, USA.