[1] Univ Texas Houston, Hlth McGovern Med Sch, Div Pulm Med, Houston, TX 77030 USA
[2] Univ Texas Houston, Hlth McGovern Med Sch, Div Crit Care Med, Houston, TX 77030 USA
[3] Univ Texas Houston, Hlth McGovern Med Sch, Div Sleep Med, Houston, TX 77030 USA
[4] Univ Texas Houston, Hlth McGovern Med Sch, Dept Diagnost & Intervent Imaging, Houston, TX USA