1. Department of Internal Medicine, Harbor-UCLA Medical Center, Torrance, CA, USA
2. Department of Emergency Medicine, University of California, San Diego, San Diego, CA, USA
3. Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, La Jolla, CA, USA
4. Department of Orthopedic Surgery, University of California, San Diego, San Diego, CA, USA
5. Pulmonary and Critical Care Medicine, Sharp Memorial Hospital, San Diego, CA, USA