title: Relationship between extravascular lung water and severity categories of acute respiratory distress syndrome by the Berlin definition.
abstract: BACKGROUND
  The Berlin definition divides acute respiratory distress syndrome (ARDS) into three severity categories. The relationship between these categories and pulmonary microvascular permeability as well as extravascular lung water content, which is the hallmark of lung pathophysiology, remains to be elucidated. The aim of this study was to evaluate the relationship between extravascular lung water, pulmonary vascular permeability, and the severity categories as defined by the Berlin definition, and to confirm the associated predictive validity for severity.
  
  
  METHODS
  The extravascular lung water index (EVLWi) and pulmonary vascular permeability index (PVPI) were measured using a transpulmonary thermodilution method for three consecutive days in 195 patients with an EVLWi of ≥10 mL/kg and who fulfilled the Berlin definition of ARDS. Collectively, these patients were seen at 23 ICUs. Using the Berlin definition, patients were classified into three categories: mild, moderate, and severe.
  
  
  RESULTS
  Compared to patients with mild ARDS, patients with moderate and severe ARDS had higher acute physiology and chronic health evaluation II and sequential organ failure assessment scores on the day of enrollment. Patients with severe ARDS had higher EVLWi (mild, 16.1; moderate, 17.2; severe, 19.1; P <0.05) and PVPI (2.7; 3.0; 3.2; P <0.05). When categories were defined by the minimum PaO2/FIO2 ratio observed during the study period, the 28-day mortality rate increased with severity categories: moderate, odds ratio: 3.125 relative to mild; and severe, odds ratio: 4.167 relative to mild. On independent evaluation of 495 measurements from 195 patients over three days, negative and moderate correlations were observed between EVLWi and the PaO2/FIO2 ratio (r = -0.355, P<0.001) as well as between PVPI and the PaO2/FIO2 ratio (r = -0.345, P <0.001). ARDS severity was associated with an increase in EVLWi with the categories (mild, 14.7; moderate, 16.2; severe, 20.0; P <0.001) in all data sets. The value of PVPI followed the same pattern (2.6; 2.7; 3.5; P <0.001).
  
  
  CONCLUSIONS
  Severity categories of ARDS described by the Berlin definition have good predictive validity and may be associated with increased extravascular lung water and pulmonary vascular permeability.
  
  
  BACKGROUND
  UMIN-CTR ID UMIN000003627.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kushimoto
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Endo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamanouchi
authors.forename: Teruo
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ishikura
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Kitazawa
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Taira
authors.forename: Kazuo
authors.initials: K
authors.lastname: Okuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Tagami
authors.forename: Akihiro
authors.initials: A
authors.lastname: Watanabe
authors.forename: Junko
authors.initials: J
authors.lastname: Yamaguchi
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yoshikawa
authors.forename: Manabu
authors.initials: M
authors.lastname: Sugita
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kase
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanemura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Yuuichi
authors.initials: Y
authors.lastname: Kuroki
authors.forename: Hiroo
authors.initials: H
authors.lastname: Izumino
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Rinka
authors.forename: Ryutarou
authors.initials: R
authors.lastname: Seo
authors.forename: Makoto
authors.initials: M
authors.lastname: Takatori
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kaneko
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nakamura
authors.forename: Takayuki
authors.initials: T
authors.lastname: Irahara
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Saito
mesh_terms: D000368:Aged; D002199:Capillary Permeability; D015633:Extravascular Lung Water / Q000502:physiology*; D005260:Female; D006801:Humans; D008168:Lung / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012119:Respiration; D012128:Respiratory Distress Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D012720:Severity of Illness Index
chemical_list: D010100:Oxygen