1. Department of Anesthesiology, Larner College of Medicine, University of Vermont, Burlington, Vermont
2. Department of Anesthesiology and Perioperative Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
3. Department of Anesthesiology, University of Colorado, Anschutz School of Medicine, Aurora, Colorado
4. Departments of Anesthesiology, Orthopaedics and Rehabilitation, and Surgery, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA