title: Evaluation of maximal inspiratory pressure, tracheal airway occlusion pressure, and its ratio in the weaning outcome.
abstract: OBJECTIVE
  The objective of this study is to evaluate the predictive performance of maximal inspiratory pressure (Pimax), airway occlusion pressure (P 0.1), and its ratio (P 0.1/Pimax) in the weaning outcome.
  
  
  METHODS
  Seventy patients on mechanical ventilation for more than 24 hours, who fulfilled weaning criteria, were prospectively evaluated. Pimax less than -25 cm H(2)O, P 0.1 less than 4.2 cm H(2)O, and P 0.1/Pimax less than 0.14 were evaluated in all patients before spontaneous breathing trials. The receiver operating characteristic (ROC) curve was calculated to evaluate the predictive performance of each index.
  
  
  RESULTS
  Pimax presented the area under the ROC curves smaller than those for P 0.1 and P 0.1/Pimax (0.52 x 0.76 and 0.52 x 0.78; P = .004 and P = .0006, respectively), being the criteria of worst performance. P 0.1/Pimax presented excellent predictive performance in weaned patients, with sensitivity of 98.08, but with the area under the ROC curves only slightly larger than those for P 0.1 (0.78 x 0.76, respectively; P = .69).
  
  
  CONCLUSIONS
  In our study, P 0.1 and P 0.1/Pimax ratio were moderately accurate, whereas Pimax was less accurate in predicting the weaning outcome.
authors.affiliation: Intensive Care Unit, Hospital de Clínicas de Niterói, Centro-Niterói, Rio de Janeiro CEP 24020-090, Brazil. snnemer@urbi.com.br
authors.forename: Sérgio N
authors.initials: SN
authors.lastname: Nemer
authors.forename: Carmen S V
authors.initials: CS
authors.lastname: Barbas
authors.forename: Jefferson B
authors.initials: JB
authors.lastname: Caldeira
authors.forename: Bruno
authors.initials: B
authors.lastname: Guimarães
authors.forename: Leandro M
authors.initials: LM
authors.lastname: Azeredo
authors.forename: Ricardo
authors.initials: R
authors.lastname: Gago
authors.forename: Paulo Cesar P
authors.initials: PC
authors.lastname: Souza