[1] Washington Univ St Louis, Sch Med, Dept Anesthesiol, 660 S Euclid Ave,POB 8054, St Louis, MO 63110 USA
[2] Washington Univ St Louis, Sch Med, Dept Orthopaed Surg, St Louis, MO USA
[3] Univ Arkansas Med Sci, Arkansas Children Hosp, Dept Anesthesiol & Pain Management, Little Rock, AR USA
[4] Univ Kansas Hlth Syst, St Francis Hosp, Dept Pain Management, Topeka, KS USA
[5] Washington Univ St Louis, Sch Med, Bernard Becker Med Lib, St Louis, MO USA
[6] Washington Univ St Louis, Sch Med, Dept Surg, St Louis, MO USA