[1] Duke Univ, Med Ctr, Dept Surg, Div Emergency Med, DUMC Box 3096, Durham, NC 27706 USA
[2] Duke Univ, Med Ctr, Sch Nursing, Durham, NC 27706 USA
[3] Duke Univ, Med Ctr, Dept Med, Div Hematol, Durham, NC 27706 USA
[4] Johns Hopkins Univ, Sch Med, Div Hematol, Baltimore, MD 21218 USA
[5] Wake Forest Sch Med, Dept Emergency Med, Winston Salem, NC USA