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Oxygen consumption and PEEPe in ventilated COPD patients
J-Ch Glérant1, O Leleu, D Rose
1Respiratory Department and Intensive Care Unit, 80054 Amiens Cedex 1, France.
Respiratory Physiology & Neurobiology
|March 16, 2005
Summary
Applying extrinsic positive-end-expiratory pressure (PEEPe) equal to intrinsic positive-end-expiratory pressure (PEEPi) significantly reduces oxygen consumption in mechanically ventilated COPD patients. A PEEPe of 5 cmH2O is recommended for patients with FEV1 ≤ 1000 ml.
Area of Science:
- Respiratory Physiology
- Critical Care Medicine
Background:
- Intrinsic positive-end-expiratory pressure (PEEPi) elevates inspiratory load and oxygen consumption (V(O2)) in ventilated patients.
- Extrinsic positive-end-expiratory pressure (PEEPe) can mitigate inspiratory threshold load, but optimal levels remain debated.
Purpose of the Study:
- To investigate the effect of different PEEPe levels on V(O2) in mechanically ventilated COPD patients.
- To determine the optimal PEEPe to reduce V(O2) demands imposed by PEEPi.
Main Methods:
- Nine mechanically ventilated COPD patients were studied.
- PEEPe levels were set at 0%, 50%, and 100% of measured static PEEPi.
- V(O2) was measured using an automatic gas analyzer during synchronized intermittent mandatory ventilation (SIMV).
Main Results:
- Static PEEPi significantly correlated with airflow obstruction (FEV1).
- Applying PEEPe equal to static PEEPi significantly decreased V(O2).
- V(O2) changes were unpredictable at 50% PEEPe, but decreased progressively up to 100% PEEPi.
Conclusions:
- Increasing PEEPe up to the level of static PEEPi progressively reduces V(O2) in ventilated COPD patients.
- A PEEPe of 5 cmH2O is recommended for mechanically ventilated COPD patients with FEV1 ≤ 1000 ml to decrease oxygen consumption.