title: The authors reply.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, South Korea Division of Cardiology, Department of Internal Medicine and Cardiovascular Center, Seoul National University Hospital, Jongno-gu, Seoul, South Korea.
authors.forename: Young-Jae
authors.initials: YJ
authors.lastname: Cho
authors.forename: Joo Myung
authors.initials: JM
authors.lastname: Lee
mesh_terms: D006801:Humans; D056888:Patient Positioning; D016684:Prone Position / Q000502:physiology*; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000628:therapy*