title: The timed inspiratory effort: a promising index of mechanical ventilation weaning for patients with neurologic or neuromuscular diseases.
abstract: BACKGROUND
  The aim of this study was to evaluate the performance of the recently described timed inspiratory effort (TIE) index in comparison with 4 other previously reported indices as to the weaning outcome in patients with neurologic or neuromuscular disorders.
  
  
  METHODS
  This observational prospective study included subjects undergoing weaning from mechanical ventilation. The performance of the indices was evaluated by calculation of the area under the receiver operating characteristic curves. The areas under the curve were compared using the Hanley and McNeil method. P values<.05 were considered significant.
  
  
  RESULTS
  Seventy-two subjects (57±20 y old) were selected for the study. Forty-three subjects were weaned, and 21 died during the study period. The mean duration of mechanical ventilation was 22.3±19.4 d. The areas under the curve of 5 weaning predictors (TIE index, integrative weaning index, noninvasive tension-time index, maximum inspiratory pressure, and breathing frequency/tidal volume index) were significantly higher than those of the other indices. The TIE index had the largest area under the curve (0.96±0.02) in comparison with the integrative weaning index (0.82±0.05, P=.009), noninvasive tension-time index (0.80±0.05, P=.001), maximum inspiratory pressure (0.77±0.06, P=.001), and breathing frequency/tidal volume index (0.72±0.06, P=.001).
  
  
  CONCLUSIONS
  In patients with neurologic or neuromuscular impairment, the TIE index had a better performance than the best weaning indices used in clinical practice.
authors.affiliation: Medical Science Post-graduation Program leonardo.uti@gmail.com.
authors.forename: Leonardo Cordeiro
authors.initials: LC
authors.lastname: de Souza
authors.affiliation: Physiotherapy School, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Fernando Silva
authors.initials: FS
authors.lastname: Guimarães
authors.affiliation: Nephrology Division, Department of Medicine, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Jocemir Ronaldo
authors.initials: JR
authors.lastname: Lugon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001930:Brain Injuries / Q000503:physiopathology; D002574:Cervical Vertebrae; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009468:Neuromuscular Diseases / Q000503:physiopathology; D011175:Positive-Pressure Respiration; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D056152:Respiratory Rate; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D020521:Stroke / Q000503:physiopathology; D013990:Tidal Volume; D013997:Time Factors; D015300:Ventilator Weaning; D014939:Work of Breathing / Q000502:physiology*
keywords: critical care; maximum inspiratory pressure; mechanical ventilation; respiratory muscle; weaning