[1] Vanderbilt Univ, Sch Med, Div Anesthesiol Crit Care Med, 1211 21st Ave S,Med Arts Bldg 526, Nashville, TN 37212 USA
[2] Vanderbilt Univ, Sch Med, Div Pulm & Crit Care Med, Nashville, TN 37212 USA
[3] Vanderbilt Univ, Sch Med, Ctr Hlth Serv Res, Nashville, TN 37212 USA
[4] Tennessee Valley Healthcare Syst, Res Serv, Nashville Vet Affairs Med Ctr, Nashville, TN USA
[5] Vanderbilt Univ, Sch Med, Dept Orthoped Surg & Phys Med & Rehabil, Nashville, TN 37212 USA
[6] Vanderbilt Univ, Sch Med, Dept Biostat, Nashville, TN 37212 USA
[7] Vanderbilt Univ, Sch Med, Div Anesthesiol Crit Care Med, Nashville, TN 37212 USA