An Investigation of Various Inspiratory Times and Inflation Pressures during Airway Pressure Release Ventilation

Abstract

An Evaluation of Various Inspiratory Times and Inflation Pressures During Airway Pressure Release Ventilation. Introduction: There are few recommendations how best to apply certain modes of mechanical ventilation, and the application of Airway Pressure Release Ventilation (APRV) requires strategic implementation of specific inspiratory (I-time) and expiratory times (E-time) and particular mean airway pressures (MAWP), neither of which is standardized. We sought to identify whether an ideal I-time or MAWP could be identified to favor more positive clinical outcomes. Methods: A retrospective analysis of archived electronic health record data to evaluate the clinical outcomes of adult patients that had been placed on APRV for a target of at least 8 hours. 68 adult subjects were evaluated from a convenient sample. Results: All outcomes of interest (surrogates) for shortterm clinical outcomes to include the PaO2/FiO2 (P/F) ratio, Oxygen Index (OI), Oxygen Saturation Index (OSI), and Modified Sequential Organ Failure Assessment (MSOFA) scores showed improvement after at least approximately 8 hours on APRV. Most notably, there was significant improvement in P/F ratio (p = 0.012) and OSI (p = 0.000). Results of regression analysis showed MAWP as a significant positive predictor of post-APRV OSI and P high as a significant positive predictor of post-APRV MSOFA score. Conclusion: In summary, it was found that settings for P high, Plow, and T low in addition to overall MAWP and Body Mass Index (BMI) had significant correlation to impact at least one of the short-term clinical outcomes measured with a lower setting for both P high and MAWP predictive of a better post-APRV OSI and MSOFA score.