[1] Univ Vermont, Dept Surg, Div Emergency Med, Larner Coll Med, Burlington, VT 05401 USA
[2] Univ Vermont, Emergency Med Residency, Larner Coll Med, Burlington, VT 05401 USA
[3] Univ Texas Hlth Sci Ctr San Antonio, Dept Emergency Med, San Antonio, TX 78229 USA
[4] Brooke Army Med Ctr, San Antonio Uniformed Serv Hlth Educ Consortium S, Emergency Med, Ft Sam Houston, TX 78234 USA