1. Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, Washington.
2. Division of Pulmonary and Critical Care Medicine, Intermountain Medical Center and the University of Utah, Salt Lake City, Utah.
3. Yellowstone National Park, Bozeman, Montana.
4. Himalayan Rescue Association Everest Base Camp Medical Clinic, Nepal.
5. Department of Emergency Medicine, University of Colorado, Denver, Colorado.
6. Institute for Altitude Medicine, Telluride, Colorado.