title: Disassociating Lung Mechanics and Oxygenation in Pediatric Acute Respiratory Distress Syndrome.
abstract: OBJECTIVE
  Both oxygenation and peak inspiratory pressure are associated with mortality in pediatric acute respiratory distress syndrome. Since oxygenation and respiratory mechanics are linked, it is difficult to identify which variables, pressure or oxygenation, are independently associated with outcome. We aimed to determine whether respiratory mechanics (peak inspiratory pressure, positive end-expiratory pressure, ΔP [PIP minus PEEP], tidal volume, dynamic compliance [Cdyn]) or oxygenation (PaO2/FIO2) was associated with mortality.
  
  
  METHODS
  Prospective, observational, cohort study.
  
  
  METHODS
  University affiliated PICU.
  
  
  METHODS
  Mechanically ventilated children with acute respiratory distress syndrome (Berlin).
  
  
  METHODS
  None.
  
  
  RESULTS
  Peak inspiratory pressure, positive end-expiratory pressure, ΔP, tidal volume, Cdyn, and PaO2/FIO2 were collected at acute respiratory distress syndrome onset and at 24 hours in 352 children between 2011 and 2016. At acute respiratory distress syndrome onset, neither mechanical variables nor PaO2/FIO2 were associated with mortality. At 24 hours, peak inspiratory pressure, positive end-expiratory pressure, ΔP were higher, and Cdyn and PaO2/FIO2 lower, in nonsurvivors. In multivariable logistic regression, PaO2/FIO2 at 24 hours and ΔPaO2/FIO2 (change in PaO2/FIO2 over the first 24 hr) were associated with mortality, whereas pressure variables were not. Both oxygenation and pressure variables were associated with duration of ventilation in multivariable competing risk regression.
  
  
  CONCLUSIONS
  Improvements in oxygenation, but not in respiratory mechanics, were associated with lower mortality in pediatric acute respiratory distress syndrome. Future trials of mechanical ventilation in children should focus on oxygenation (higher PaO2/FIO2) rather than lower peak inspiratory pressure or ΔP, as oxygenation was more consistently associated with outcome.
authors.affiliation: 1Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA.2Division of Pediatric Critical Care Medicine, Department of Pediatrics and Public Health Science, Penn State Hershey Children's Hospital, Hershey, PA.
authors.forename: Nadir
authors.initials: N
authors.lastname: Yehya
authors.forename: Neal J
authors.initials: NJ
authors.lastname: Thomas
mesh_terms: D000293:Adolescent; D001784:Blood Gas Analysis; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D015278:Intensive Care Units, Pediatric; D008168:Lung / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000401:mortality / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*
chemical_list: D010100:Oxygen