title: Clinical relevance of classification according to weaning difficulty.
abstract: OBJECTIVE
  To evaluate the clinical relevance of the weaning from mechanical ventilation classification system derived from the 2005 international consensus conference, in patients who receive mechanical ventilation for more than 48 hours, and evaluate its correlation with prognosis.
  
  
  METHODS
  We conducted a retrospective cohort study in a 12-bed intensive care unit (ICU) in a teaching hospital. We included patients who required > 48 hours of mechanical ventilation and who passed a spontaneous breathing trial (SBT). Weaning and sedation were monitored according to standardized protocol-directed procedures. We collected data on physiological characteristics, mechanical ventilation duration, ICU and hospital stay, and mortality from the medical records database. We assessed one-year mortality with a prospective, standardized method. Multivariate logistic regression was performed to evaluate the association between weaning categories and outcome.
  
  
  RESULTS
  We included 329 ventilation episodes, in which 115 patients passed at least one SBT. Thirty-four patients (30%) succeeded in their first SBT (simple weaning group), 47 patients (40%) succeeded in their 2nd or 3rd SBT or in less than 7 days of weaning (the difficult weaning group), and 34 patients (30%) required more than 3 SBTs or more than 7 days of weaning (the prolonged weaning group). There were significant differences in ICU and hospital mortality between the simple, difficult, and prolonged-weaning groups. Prolonged weaning was an independent risk factor for longer ICU stay (odds ratio 15.11, 95% CI 1.61-141.91, P = .01) and hospital mortality (odds ratio 3.66, 95% CI 0.99-13.51). However, the weaning process did not impact one-year mortality (odds ratio 2.61, 95% CI 0.82-8.35).
  
  
  CONCLUSIONS
  The new weaning classification system is clinically relevant and correlates to ICU and hospital mortality, but not to one-year mortality.
authors.affiliation: Réanimation Médicale, Pôle Urgences-Anesthésie- Réanimation, Centre Hospitalier Universitaire Brest, Brest, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Tonnelier
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Tonnelier
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Nowak
authors.forename: Christophe
authors.initials: C
authors.lastname: Gut-Gobert
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Prat
authors.forename: Anne
authors.initials: A
authors.lastname: Renault
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Boles
authors.forename: Erwan
authors.initials: E
authors.lastname: L'Her
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012121:Respiration, Artificial / Q000379:methods*; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D014481:United States / Q000453:epidemiology; D015300:Ventilator Weaning / Q000145:classification* / Q000401:mortality