1. Stanford University School of Medicine, Stanford, California, USA
2. Department of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, USA
3. Anesthesiology and Perioperative Care Service, VA Palo Alto Health Care System, Palo Alto, California, USA
4. Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, California, USA
5. Department of Health Research and Policy, Stanford University School of Medicine, Stanford, California, USA