[1] Univ Utah, Dept Med, Div Resp Crit Care & Occupat Pulm Med, Salt Lake City, UT 84112 USA
[2] Intermt Med Ctr, Div Emergency Med, Sorenson Heart & Lung Bldg,6th Floor, Murray, UT 84107 USA
[3] Univ Utah, Dept Surg, Div Emergency Med, Salt Lake City, UT USA
[4] Intermt Med Ctr, Div Pulm & Crit Care Med, Sorenson Heart & Lung Bldg,6th Floor, Murray, UT 84107 USA