[1] Univ Pittsburgh, Dept Hlth & Community Syst, Sch Nursing, 426 Victoria Bldg,3500 Victoria St, Pittsburgh, PA 15261 USA
[2] Vanderbilt Univ, Med Ctr, Dept Biostat, Nashville, TN USA
[3] Univ Pittsburgh, Sch Nursing, Dept Nurse Anesthesia, Pittsburgh, PA 15261 USA
[4] Univ Pittsburgh, Sch Med, UPMC Dept Anesthesiol & Perioperat Med, Pittsburgh, PA 15261 USA
[5] Univ Pittsburgh, Dept Elect & Comp Engn, Pittsburgh, PA 15261 USA