[1] Univ Calgary, Dept Emergency Med, Calgary, AB, Canada
[2] Mayo Clin, Dept Emergency Med, Rochester, MN USA
[3] George Washington Univ, Dept Emergency Med, Washington, DC USA
[4] Sinai Grace Hosp, Detroit Med Ctr, Dept Emergency Med, Detroit, MI USA
[5] Mt Sinai Hosp, Dept Emergency Med, New York, NY 10029 USA
[6] Univ Calif San Francisco, Dept Emergency Med, San Francisco, CA 94143 USA
[7] Univ Texas Southwestern, Dept Emergency Med, Dallas, TX USA