1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
2. Division of Critical Care Medicine, Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
3. Pulmonary Section, Medicine Service, VA Palo Alto Health Care System, Palo Alto, CA, USA
4. Anesthesiology and Perioperative Care Service, VA Palo Alto Health Care System, Palo Alto, CA, USA