Evaluation of maximal inspiratory pressure, tracheal airway occlusion pressure, and its ratio in the weaning outcome

J Crit Care. 2009 Sep;24(3):441-6. doi: 10.1016/j.jcrc.2009.01.007. Epub 2009 Mar 27.


Purpose: 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.

Materials and 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).

Conclusion: 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.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Airway Obstruction / physiopathology*
  • Female
  • Humans
  • Inhalation / physiology*
  • Inspiratory Capacity / physiology
  • Male
  • Middle Aged
  • Ventilator Weaning*