title: The ALIEN study: incidence and outcome of acute respiratory distress syndrome in the era of lung protective ventilation.
abstract: OBJECTIVE
  While our understanding of the pathogenesis and management of acute respiratory distress syndrome (ARDS) has improved over the past decade, estimates of its incidence have been controversial. The goal of this study was to examine ARDS incidence and outcome under current lung protective ventilatory support practices before and after the diagnosis of ARDS.
  
  
  METHODS
  This was a 1-year prospective, multicenter, observational study in 13 geographical areas of Spain (serving a population of 3.55 million at least 18 years of age) between November 2008 and October 2009. Subjects comprised all consecutive patients meeting American-European Consensus Criteria for ARDS. Data on ventilatory management, gas exchange, hemodynamics, and organ dysfunction were collected.
  
  
  RESULTS
  A total of 255 mechanically ventilated patients fulfilled the ARDS definition, representing an incidence of 7.2/100,000 population/year. Pneumonia and sepsis were the most common causes of ARDS. At the time of meeting ARDS criteria, mean PaO(2)/FiO(2) was 114 ± 40 mmHg, mean tidal volume was 7.2 ± 1.1 ml/kg predicted body weight, mean plateau pressure was 26 ± 5 cmH(2)O, and mean positive end-expiratory pressure (PEEP) was 9.3 ± 2.4 cmH(2)O. Overall ARDS intensive care unit (ICU) and hospital mortality was 42.7% (95%CI 37.7-47.8) and 47.8% (95%CI 42.8-53.0), respectively.
  
  
  CONCLUSIONS
  This is the first study to prospectively estimate the ARDS incidence during the routine application of lung protective ventilation. Our findings support previous estimates in Europe and are an order of magnitude lower than those reported in the USA and Australia. Despite use of lung protective ventilation, overall ICU and hospital mortality of ARDS patients is still higher than 40%.
authors: CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain. jesus.villar54@gmail.com
authors: Jesús
authors: J
authors: Villar
authors: Jesús
authors: J
authors: Blanco
authors: José Manuel
authors: JM
authors: Añón
authors: Antonio
authors: A
authors: Santos-Bouza
authors: Lluís
authors: L
authors: Blanch
authors: Alfonso
authors: A
authors: Ambrós
authors: Francisco
authors: F
authors: Gandía
authors: Demetrio
authors: D
authors: Carriedo
authors: Fernando
authors: F
authors: Mosteiro
authors: Santiago
authors: S
authors: Basaldúa
authors: Rosa Lidia
authors: RL
authors: Fernández
authors: Robert M
authors: RM
authors: Kacmarek
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000628:therapy; D013030:Spain / Q000453:epidemiology; D055397:Ventilator-Induced Lung Injury / Q000517:prevention & control*