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A method for determining optimal mean airway pressure in high-frequency oscillatory ventilation
Brian Casserly1, F Dennis McCool, Jigme M Sethi
1Division of Pulmonary, Critical Care and Sleep Medicine, The Memorial Hospital of Rhode Island, Pawtucket, RI, USA. brian_casserly@brown.edu
Lung
|November 8, 2012
Summary
Determining optimal mean airway pressure (MAP) during high-frequency oscillatory ventilation (HFOV) for acute respiratory distress syndrome (ARDS) can be guided by PaO2 measurements, serving as a surrogate for lung volume. This simplifies monitoring for effective alveolar recruitment and preventing overdistention.
Area of Science:
- Critical Care Medicine
- Respiratory Physiology
- Mechanical Ventilation
Background:
- Optimal mean airway pressure (MAP) in high-frequency oscillatory ventilation (HFOV) balances alveolar recruitment and prevents overdistention.
- The point of maximal curvature (PMC) on the lung's volume-pressure curve guides optimal MAP selection.
- Accurate determination of optimal MAP is crucial for patients with acute respiratory distress syndrome (ARDS).
Purpose of the Study:
- To evaluate if PaO2 measurements can determine optimal MAP at the PMC during HFOV in ARDS patients.
- To assess the utility of non-invasive measures for guiding ventilator settings.
Main Methods:
- Prospective study of seven ARDS patients on HFOV after conventional ventilation failure.
- Validation of end-expiratory lung volume (∆EELV) changes using magnetometry against spirometry in healthy subjects.
- Comparison of MAP at PMC derived from ∆EELV versus PaO2 measurements in ARDS patients.
Main Results:
- Magnetometry measurements of ∆EELV were validated against spirometry.
- MAP at the PMC was identical using both ∆EELV and PaO2 methods in all ARDS patients.
- A significant correlation (p < 0.001) was found between MAP-associated changes in PaO2 and ∆EELV.
Conclusions:
- Bedside PaO2 measurements can serve as a reliable surrogate for end-expiratory lung volume (EELV) measurements.
- This finding simplifies the determination of optimal MAP during HFOV in ARDS.
- PaO2 monitoring offers a practical approach to optimize lung recruitment and minimize overdistention.
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