[1] Washington Hosp Ctr, Pulm Serv, Washington, DC 20010 USA
[2] Washington Hosp Ctr, Crit Care Serv, Washington, DC 20010 USA
[3] Washington Hosp Ctr, Resp Serv, Washington, DC 20010 USA
[4] 3M Pharmaceut, Clin Res, St Paul, MN USA
[5] Natl Jewish Med & Res Ctr, Denver, CO USA