[1] Duke Univ, Med Ctr, Intens Care Unit, Durham, NC USA
[2] Duke Univ Hosp, Heart Serv Nursing Operat & Patient Care Serv, Durham, NC USA
[3] Duke Univ, Durham, NC USA
[4] Duke Univ, Med Ctr, 10 Duke Med Circle, Durham, NC 27710 USA
[5] Duke Univ Hosp, Durham, NC USA