[1] Georgetown Univ, Sch Med, MedStar Georgetown Univ Hosp, Washington, DC 20007 USA
[2] Harvard Med Sch, Dept Anesthesia Crit Care & Pain Med, Beth Israel Deaconess Med Ctr, Boston, MA 02115 USA
[3] Univ Arizona, Coll Med Phoenix, Dept Anesthesiol, Phoenix, AZ USA
[4] Louisiana State Univ, Anesthesiol, Hlth Sci Ctr, Shreveport, LA 71105 USA