1 Department of Emergency Medicine, Vanderbilt University Medical Center, 1313 21st Avenue South, 703 Oxford House, Nashville, TN, 37323-4700, USA.
2 Department of Emergency Medicine, Vanderbilt University Medical Center, 1313 21st Avenue South, 703 Oxford House, Nashville, TN, 37323-4700, USA. erik.hess@vumc.org.