[1] Duke Univ, Sch Med, Dept Emergency Med, Durham, NC 27708 USA
[2] Dartmouth Hitchcock Med Ctr, Dept Anesthesiol, Lebanon, NH USA
[3] Massachusetts Gen Hosp, Dept Anesthesiol, Boston, MA USA
[4] Hosp Special Surg, Dept Anesthesiol, Crit Care & Pain Management, New York, NY USA
[5] Weill Cornell Med Coll, Dept Anesthesiol, New York, NY USA
[6] Case Western Reserve Univ, Metrohlth Med Ctr, Dept Emergency Med, Cleveland, OH USA
[7] Mayo Clin, Dept Anesthesiol, Rochester, MN USA
[8] Duke Univ, Dept Anesthesiol, Sch Med, Durham, NC USA