1 Section of Orthopedic Anesthesiology, Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: Nabil.Elkassabany@uphs.upenn.edu.
2 Anesthesiology and Perioperative Care Service, Inpatient Surgical Services, Veterans Affairs Palo Alto Health Care System, Department of Anesthesiology, Perioperativeand Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA. Electronic address: emariano@stanford.edu.