1. Department of Anesthesiology, Thomas Jefferson University Hospitals, Philadelphia, PA
2. Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN
3. Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN
4. Department of Anesthesiology and Critical Care Medicine, George Washington University School of Medicine and Health Sciences, Washington DC
5. Missoula Anesthesiology PC, Missoula, MT
6. Department of Cardiac Surgery, Vanderbilt University Medical Center, Nashville, TN.