Distribution and mechanisms of lung injury induced by spontaneous breathing in experimental acute respiratory distress syndrome: A comprehensive investigation towards improvement of protective mechanical ventilation
Final Report Abstract
The present project could add new relevant information to the field of mechanical ventilation. We could show that different degrees of spontaneous breathing during mechanical ventilation in an experimental model of moderate ARDS have distinct impact on lung function and damage. According to our results, levels of spontaneous breathing higher than currently used in clinical practice, i.e. responding for > 30% of the total minute volume are necessary to maximize the improvement in gas exchange and to decrease lung damage as compared to protective controlled mechanical ventilation. The mechanism for those findings is a sustainable decrease in global stress and strain in lungs. On the other hand, we could observe that spontaneous breathing added to ultra-protective mechanical ventilation could worsen lung injury in a model of severe ARDS. To the best of our knowledge, this information is original. The perhaps most striking issue raised by the results of this project is that the level of spontaneous breathing necessary to obtain lung protection, as compared to controlled protective ventilation, is higher than previously thought. Thus, clinical trials that may address the issue of spontaneous breathing in mild to moderate ARDS should take these results into account in the planning phase already. Since our group is also conducting clinical studies, we intend to perform a pilot trial for assessing the feasibility of such a trial. A number of relevant questions have also arisen from the present project. Our results seem to suggest that not only the severity of the lung damage, but also the stability of lung aeration at the end of expiration are determinants of the beneficial or even harmful effects of spontaneous breathing in ARDS. Given that we accumulated experience and know-how with different investigational tools during this project, we thus intend to investigate such hypothesis in a new series of experimental studies in the near future.
