[1] Vanderbilt Univ, Dept Anesthesiol, Sch Med, Nashville, TN USA
[2] Brigham & Womens Hosp, Dept Anesthesiol Perioperat & Pain Med, Boston, MA USA
[3] Southeast Hlth Med Ctr, Dept Anesthesiol, Dothan, AL USA
[4] Tufts Med Ctr, Dept Anesthesiol, Boston, MA USA