[1] Department of Otorhinolaryngology/Head and Neck Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA 19104-4283
[2] Departments of Otorhinolaryngology/Head and Neck Surgery, Hospital of the University of Pennsylvania, Philadelphia
[3] Department of Anesthesia, Hospital of the University of Pennsylvania, Philadelphia
[4] Department of Nursing Service, School of Nursing, Hospital of the University of Pennsylvania, Philadelphia
[5] Department of Otolaryngology/Head and Neck Surgery, University of California, San Francisco
[6] Department of Anesthesiology and Critical Care, Johns Hopkins University, Baltimore, MD