[1] Texas Tech Univ Hlth Sci Ctr Paul L Foster Sch Me, Dept Internal Med, Div Resp Med, El Paso, TX 79905 USA
[2] Texas Tech Univ Hlth Sci Ctr Paul L Foster Sch Me, Div Resp & Crit Care Med, El Paso, TX 79905 USA
[3] Beneficencia Espanola, Dept Internal Med, Tampico, Mexico
[4] Intermt Med Ctr, Dept Med, Div Pulm & Crit Care Med, Murray, UT USA
[5] Univ Utah Hlth Sci Ctr, Salt Lake City, UT USA