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