[1] George Washington Univ, Ringgold Stand Inst, Sch Med & Hlth Sci, Dept Pulm & Crit Care Med, Washington, DC 20037 USA
[2] George Washington Univ, Ringgold Stand Inst, Sch Med & Hlth Sci, Dept Emergency Med, Washington, DC 20037 USA
[3] Univ Maryland, Ringgold Stand Inst, Sch Med, Dept Emergency Med, Baltimore, MD 21201 USA
[4] Univ Maryland, Ringgold Stand Inst, R Adams Cowley Shock Trauma Ctr, Sch Med, Baltimore, MD 21201 USA