title: [Utility of the dead space fraction (Vd/Vt) as a predictor of extubation success].
abstract: OBJECTIVE
  To determine the value of Vd/Vt as a predictor of extubation failure in patients with mechanical ventilation admitted to the intensive care units.
  
  
  METHODS
  A prospective, observational cohort study conducted from 1 September 2010 to 1 March 2011.
  
  
  METHODS
  General intensive care unit (G-ICU) of a third level university hospital.
  
  
  METHODS
  The study included patients on mechanical ventilation (MV) for over 12 hours, and who in the process of weaning were subjected to low-level pressure support. Exclusion criteria were age under 18 years, ventilation via tracheotomy and patients failing to cooperate for different reasons. During the study, 392 patients were admitted to the G-ICU; of these, 214 required MV. The weaning process was started in 154 cases. Fifty-four patients were excluded from the study, and 24 were not extubated from MV. A total of 76 patients were finally extubated and analyzed.
  
  
  METHODS
  Vd/Vt was calculated as the ratio (PaCO(2)-Pє CO(2))/PaCO(2), with the recorded parameters.
  
  
  RESULTS
  Logistic regression analysis showed a significant association between the Vd/Vt and extubation failure, with OR=1.52 (95%CI 1.11 to 2.09, p=0.008). The area under the ROC curve with respect to the prediction of extubation failure according to the Vd/Vt value was 0.94 (95%CI 0.86 to 0.98, p<0.0001).
  
  
  CONCLUSIONS
  Vd/Vt is a powerful predictor of extubation failure in patients on MV.
authors.affiliation: Servicio de Medicina Intensiva, Hospital Universitario Marqués de Valdecilla, Santander, España. jandro120475@hotmail.com
authors.forename: A
authors.initials: A
authors.lastname: González-Castro
authors.forename: V
authors.initials: V
authors.lastname: Suárez-Lopez
authors.forename: V
authors.initials: V
authors.lastname: Gómez-Marcos
authors.forename: C
authors.initials: C
authors.lastname: González-Fernandez
authors.forename: D
authors.initials: D
authors.lastname: Iglesias-Posadilla
authors.forename: J
authors.initials: J
authors.lastname: Burón-Mediavilla
authors.forename: J C
authors.initials: JC
authors.lastname: Rodríguez-Borregan
authors.forename: E
authors.initials: E
authors.lastname: Miñambres
authors.forename: J
authors.initials: J
authors.lastname: Llorca
mesh_terms: D018806:APACHE; D000368:Aged; D060666:Airway Extubation; D002318:Cardiovascular Diseases / Q000628:therapy; D045422:Continuous Positive Airway Pressure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy; D012126:Respiratory Dead Space; D015300:Ventilator Weaning / Q000379:methods