Static lung/thorax compliance measurements during mechanical ventilation are not useful in predicting extubation failures

Bryan DeHaven, O. C. Kirton, David V Shatz, J. Morgan

Research output: Contribution to journalArticlepeer-review


Purpose: Many objective measurements have been proposed to identify patients likely to remain successfully extubated following mechanical ventilation, and those likely to be reintubated and returned to the ventilator. Measurement of the lung and thorax compliance (CLTH) can be accomplished by use of the plateau pressure at the end of an end-inspiratory pause and the exhaled volume of the mechanical ventilator, inferring how 'hard' the patient might work during spontaneous breathing. End-inspiratory pause pressure avoids contributions to peak pressure from endotracheal tube flow resistance, and variations in inspiratory time and/or flow rates and patterns. We evaluated whether this data clarified which patients would not tolerate withdrawal of mechanical ventilation. Methods: Prospective, descriptive cohort study over 6 months in a 20 bed Trauma ICU, n = 209 patients extubated from mechanical ventilation. Mean age of 42 years (range 14-90). Pre-extubation trials used both objective (room air CPAP trial) and subjective (airway protection, level of consciousness) criteria, and were the sole criteria used for extubation decisions. Mechanical ventilators either compensated for circuit compressible volume (PB 7200ae) or measured volume at the proximal airway (Hamilton Veolar). CLTH measurement added a 1.0 second end-inspiratory pause to the ventilator cycle, with pressure and exhaled tidal volume recorded. Pressure was divided into volume to yield CLTH (ml/cmH2O). Results: Mechanical ventilation was re-instituted in 17/209 (8%) of extubated patients. Calculated CLTH of the entire cohort was low. unpaired t-test p=ns. CLTHml/cmH2O mean std dev 95% distrb range n = 192 32 ±10 12 to 52 15-64 n = 17 33 ±8 17 to 49 21-53 15 of 17 patients failing extubation had measured Clth within 1 standard deviation of the mean, while of the remaining 2 patients, 1 was within 2 standard deviations of the mean at 21ml/cmH2O, and 1 slightly outside of 2 standard deviations of the mean, at 53ml/cmH2O. Conclusions: Static lung/thorax compliance provided no useful distinguishing classification of those patients intolerant of withdrawal of mechanical ventilation. Clinical Implications: Reliance on CLTH may delay extubation if the value is perceived by the clinician as 'too low.'.

Original languageEnglish (US)
Issue number4 SUPPL.
StatePublished - Oct 1998
Externally publishedYes

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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