[1] King Saud Med City, Crit Care Dept, POB 331905, Riyadh 11373, Saudi Arabia
[2] Johns Hopkins Univ Hosp, Dept Med, Baltimore, MD 21205 USA
[3] King Saud Med City, Res & Innovat Ctr, Riyadh, Saudi Arabia
[4] Univ Southern Calif, Keck Sch Med, Crit Care Dept, Los Angeles, CA 90007 USA