[1] Hallym Univ, Dongtan Sacred Heart Hosp, Dept Internal Med, Div Pulm Allergy & Crit Care Med, Hwaseong, South Korea
[2] Natl Med Ctr, Dept Internal Med, Div Pulm & Crit Care Med, Seoul, South Korea
[3] Seoul Metropolitan Govt Seoul Natl Univ Boramae M, Div Pulm & Crit Care, Dept Internal Med, Seoul, South Korea