1 Department of Emergency Medicine, Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Ground Ravdin, 3400 Spruce Street, Philadelphia, PA 19104, USA. Electronic address: [email protected].
2 Department of Emergency Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; 900 Welch Road, Suite 350, Palo Alto, CA 94304, USA. Electronic address: [email protected].