title: High Positive End-Expiratory Pressure Is Associated with Improved Survival in Obese Patients with Acute Respiratory Distress Syndrome.
abstract: BACKGROUND
  In acute respiratory distress syndrome, minimizing lung injury from repeated collapse and reopening of alveoli by applying a high positive end-expiratory pressure improves oxygenation without influencing mortality. Obesity causes alveolar atelectasis, thus suggesting that a higher positive end-expiratory pressure might be more protective among the obese. We hypothesized that the effect of applying a high positive end-expiratory pressure on mortality from acute respiratory distress syndrome would differ by obesity status.
  
  
  METHODS
  This was a retrospective analysis of 505 patients from the Assessment of Low tidal Volume and elevated End-expiratory volume to Obviate Lung Injury Trial, a multicenter randomized trial that compared a higher vs a lower positive end-expiratory pressure ventilatory strategy in acute respiratory distress syndrome. We examined the relationship between positive end-expiratory pressure strategy and 60-day mortality stratified by obesity status.
  
  
  RESULTS
  Among obese patients with acute respiratory distress syndrome, those assigned to a high positive end-expiratory pressure strategy experienced lower mortality compared with those assigned to a low strategy (18% vs 32%; P = .04). Among the nonobese, those assigned to high positive end-expiratory pressure strategy experienced similar mortality with those assigned to low strategy (34% vs 23%; P = .13). Multivariate analysis demonstrated an interaction between obesity status and the effect of positive end-expiratory pressure strategy on mortality (P <.01).
  
  
  CONCLUSIONS
  Ventilation with higher levels of positive end-expiratory pressure was associated with improved survival among the subgroup of patients with acute respiratory distress syndrome who are obese.
authors.affiliation: Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine, Department of Medicine, University of Arizona College of Medicine, Tucson; University of Arizona Health Sciences, Tucson. Electronic address: cbime@email.arizona.edu.
authors.forename: Christian
authors.initials: C
authors.lastname: Bime
authors.affiliation: Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson.
authors.forename: Mallorie
authors.initials: M
authors.lastname: Fiero
authors.affiliation: University of Arizona Health Sciences, Tucson; BiO5 Institute - The University of Arizona, Tucson.
authors.forename: Zhenqiang
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson.
authors.forename: Eyal
authors.initials: E
authors.lastname: Oren
authors.affiliation: Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine, Department of Medicine, University of Arizona College of Medicine, Tucson; University of Arizona Health Sciences, Tucson.
authors.forename: Cristine E
authors.initials: CE
authors.lastname: Berry
authors.affiliation: Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine, Department of Medicine, University of Arizona College of Medicine, Tucson; University of Arizona Health Sciences, Tucson.
authors.forename: Sairam
authors.initials: S
authors.lastname: Parthasarathy
authors.affiliation: Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine, Department of Medicine, University of Arizona College of Medicine, Tucson; University of Arizona Health Sciences, Tucson.
authors.forename: Joe G N
authors.initials: JGN
authors.lastname: Garcia
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000401:mortality; D011175:Positive-Pressure Respiration / Q000379:methods; D012128:Respiratory Distress Syndrome / Q000150:complications / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D012189:Retrospective Studies; D013990:Tidal Volume
keywords: ARDS; Adult; Mortality; Obesity; PEEP; Survival