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Pressure support compared with controlled mechanical ventilation in experimental lung injury
Rolf Dembinski1, Martin Max, Ralf Bensberg
1Department of Anesthesiology, Universitaetsklinikum der RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany. rolf.dembinski@post.rwth-aachen.de
Anesthesia and Analgesia
|May 29, 2002
Summary
Pressure support ventilation (PSV) improves gas exchange in acute lung injury by reducing ventilation-perfusion inequality. However, controlled mechanical ventilation (CMV) may offer more effective improvements in gas distribution.
Area of Science:
- Critical Care Medicine
- Respiratory Physiology
- Pulmonary Medicine
Background:
- Spontaneous breathing activity may enhance oxygenation in acute lung injury (ALI) via improved ventilation-perfusion (V/Q) distribution.
- Pressure support ventilation (PSV) is a common assisted spontaneous breathing mode in critical care.
Purpose of the Study:
- To investigate the prolonged effects of PSV on gas exchange in an experimental model of ALI.
- To test the hypothesis that PSV improves oxygenation through enhanced V/Q distribution.
Main Methods:
- Acute lung injury (ALI) was induced in 20 pigs using repetitive lung lavage.
- Animals were randomized to receive either PSV or controlled mechanical ventilation (CMV) with PEEP.
- Blood gas analysis and V/Q distribution were assessed over 12 hours.
Main Results:
- PSV improved oxygenation by decreasing pulmonary shunt and increasing normal V/Q ratios.
- CMV demonstrated a more pronounced reduction in pulmonary shunt compared to PSV.
- PSV reduced V/Q inequality, but CMV was potentially more effective in improving V/Q distribution.
Conclusions:
- Assisted spontaneous breathing, specifically PSV, can benefit gas exchange in ALI.
- PSV improves gas exchange in ALI by reducing V/Q inequality.
- Controlled mechanical ventilation may provide more effective V/Q distribution improvements than PSV in this ALI model.