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Breathing pattern associated with respiratory comfort during automatic tube compensation and pressure support
1Department of Anesthesiology and Critical Care Medicine, University of Freiburg, Germany. mols@ana1.ukl.ani-freiburg.de
Background:
Automatic tube compensation (ATC) is a new option to support spontaneously breathing tracheally intubated patients. We have previously demonstrated an increased respiratory comfort compared to pressure support ventilation (PSV) in volunteers. Here we characterized the breathing pattern during ATC associated with respiratory comfort in comparison to PSV. Furthermore, we studied whether ATC can be substituted by a simple modification of PSV.
Methods:
We exposed 10 volunteers breathing through a 7.5 mm endotracheal tube via mouthpiece to PSV with 1) immediate and 2) delayed pressure rise and to 3) ATC. Immediate changes of the respiratory pattern after mode shifts were analyzed in detail. Furthermore, the volunteers were instructed to indicate changes in comfort after transitions between these modes as increased, unchanged, or decreased.
Results:
Decreased comfort was associated with a substantial increase of tidal volume, minute ventilation, gas flow, and pressure. No differences in respiratory comfort were perceived between immediate and delayed pressure rise during PSV.
Conclusion:
PSV resulted in excessive tidal volumes and airflow, which was perceived as discomfort. This cannot be avoided by a delayed pressure rise but can be by the more comfortable ATC. ATC seems to adapt better to the ventilatory demand than PSV.