title: Difference in pulmonary permeability between indirect and direct acute respiratory distress syndrome assessed by the transpulmonary thermodilution technique: a prospective, observational, multi-institutional study.
abstract: BACKGROUND
  Acute respiratory distress syndrome (ARDS) is characterized by the increased pulmonary permeability secondary to diffuse alveolar inflammation and injuries of several origins. Especially, the distinction between a direct (pulmonary injury) and an indirect (extrapulmonary injury) lung injury etiology is gaining more attention as a means of better comprehending the pathophysiology of ARDS. However, there are few reports regarding the quantitative methods distinguishing the degree of pulmonary permeability between ARDS patients due to pulmonary injury and extrapulmonary injury.
  
  
  METHODS
  A prospective, observational, multi-institutional study was performed in 23 intensive care units of academic tertiary referral hospitals throughout Japan. During a 2-year period, all consecutive ARDS-diagnosed adult patients requiring mechanical ventilation were collected in which three experts retrospectively determined the pathophysiological mechanisms leading to ARDS. Patients were classified into two groups: patients with ARDS triggered by extrapulmonary injury (ARDSexp) and those caused by pulmonary injury (ARDSp). The degree of pulmonary permeability using the transpulmonary thermodilution technique was obtained during the first three intensive care unit (ICU) days.
  
  
  RESULTS
  In total, 173 patients were assessed including 56 ARDSexp patients and 117 ARDSp patients. Although the Sequential Organ Failure Assessment (SOFA) score was significantly higher in the ARDSexp group than in the ARDSp group, measurements of the pulmonary vascular permeability index (PVPI) were significantly elevated in the ARDSp group on all days: at day 0 (2.9 ± 1.3 of ARDSexp vs. 3.3 ± 1.3 of ARDSp, p = .008), at day 1 (2.8 ± 1.5 of ARDSexp vs. 3.2 ± 1.2 of ARDSp, p = .01), at day 2 (2.4 ± 1.0 of ARDSexp vs. 2.9 ± 1.3 of ARDSp, p = .01). There were no significant differences in mortality at 28 days, mechanical ventilation days, and hospital length of stay between the two groups.
  
  
  CONCLUSIONS
  The results of this study suggest the existence of several differences in the increased degree of pulmonary permeability between patients with ARDSexp and ARDSp.
  
  
  BACKGROUND
  This report is a sub-group analysis of the study registered with UMIN-CTR (IDUMIN000003627).
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Morisawa
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Fujitani
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Taira
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kushimoto
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Kitazawa
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Okuchi
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ishikura
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Teruo
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tagami
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Yamaguchi
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Sugita
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kase
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanemura
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Yuuichi
authors.initials: Y
authors.lastname: Kuroki
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Izumino
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Rinka
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Ryutarou
authors.initials: R
authors.lastname: Seo
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Takatori
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kaneko
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Irahara
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Saitou
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8603 Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Watanabe
keywords: Acute pulmonary edema; Acute respiratory distress syndrome; Direct injury; Indirect injury; Pulmonary vascular permeability; Transpulmonary thermodilution technique