1. Department of Pediatrics, Section of Critical Care Medicine, Dartmouth-Hitchcock Medical Center, Lebanon
2. Department of Pediatrics, Division of Critical Care Medicine, University of Utah, Salt Lake City, Utah, United States
3. Department of Internal Medicine, Division of Epidemiology, University of Utah, Salt Lake City, Utah, United States
4. Department of Pediatrics, Washington Permanente Medical Group, Spokane, Washington, United States