[1] Vanderbilt Univ, Med Ctr, Dept Anesthesiol, Nashville, TN USA
[2] Univ Michigan, Dept Anesthesiol, Ann Arbor, MI 48109 USA
[3] Univ Toledo, Coll Med & Life Sci, ProMed Toledo Hosp, Dept Surg, 2801 W Bancroft St, Toledo, OH 43606 USA
[4] ProMed Toledo Hosp, Dept Anesthesiol, Toledo, OH USA