title: The relationship between positive end-expiratory pressure and cardiac index in patients with acute respiratory distress syndrome.
abstract: OBJECTIVE
  The purpose of the study is to evaluate the association between positive end-expiratory pressure (PEEP) and cardiac index in patients with acute respiratory distress syndrome (ARDS).
  
  
  METHODS
  This is a secondary cross-sectional analysis of the multicenter randomized controlled Fluid and Catheter Treatment Trial enrolling adult patients within 48 hours of ARDS onset. Patients randomized to the pulmonary artery catheter arm, who had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment, were included in this study. Because FACTT had a 2 × 2 factorial design, half of the patients were in a "liberal fluids" study arm, and the other half were in a "conservative fluids" study arm.
  
  
  RESULTS
  The final study population (833 measurements or observations, in 367 patients) was comparable with the original overall FACTT study population. The mean PEEP level used was 8.2 ± 3.4 cm H2O, and the mean cardiac index was 4.2 ± 1.2 L/min per square meter. There was no association between PEEP and cardiac index in patients with ARDS, even when adjusted for Acute Physiology and Chronic Health Evaluation score, age, fluid study arm in FACTT, and sepsis.
  
  
  CONCLUSIONS
  In patients with ARDS who are managed with liberal or conservative fluid management protocols, PEEP is not associated with lower cardiac index.
authors.affiliation: Yale University, School of Medicine, Department of Internal Medicine, Section of Pulmonary, Critical Care & Sleep Medicine, New Haven, CT 06510. Electronic address: wassim.fares@yale.edu.
authors.forename: Wassim H
authors.initials: WH
authors.lastname: Fares
authors.forename: Shannon S
authors.initials: SS
authors.lastname: Carson
mesh_terms: D018806:APACHE; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D005440:Fluid Therapy; D006334:Heart Function Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome; D014481:United States
keywords: ARDS; Cardiac function; Cardiac index; Heart-lung interaction; Mechanical ventilation