Effects of positional changes on alveolar dynamics and respiratory mechanics in rats with and without acute lung injury.

肺保护性机械通气是现代麻醉和重症监护的标志，已被证明可以显著降低肺健康和损伤患者的发病率和死亡率。除了使用低潮量外，体位疗法已被证明具有有益的效果。呼吸阻力和顺应性以及血气分析通常用于床边，但仅提供有限的通气和灌注区域分布信息。此外，CT和MRI等成像方式提供了有关肺整体结构的信息，但对健康肺和损伤肺的肺泡动力学的了解有限。一般认为，特别是在低压损伤的肺中，重力依赖区域的肺泡塌陷，但目前还不能通过任何成像方式证明这一点。在本研究中，我们将在肺健康和表面活性物质耗竭引起的急性肺损伤大鼠的体内成像研究机械通气对肺泡组织结构和功能的影响。我们将在俯卧位和仰卧位对肺部的同一区域进行成像。根据重力位置推测，在同一肺区域内肺泡结构和动力会发生变化。特别是在受伤的肺中，我们假设肺泡平均较小，部分充满液体。通气参数如气道和组织阻力和顺应性将与肺泡结构成像同时测量并与之相关。我们希望通过肺泡动力学和肺弹性的结合，更好地了解机械通气过程中的生理和病理生理过程。我们的研究结果有望帮助临床医生更好地解释整体肺功能测量，并有助于更好地理解和改进肺保护性机械通气策略，以进一步降低机械通气患者的发病率和死亡率。

Lung protective mechanical ventilation is a hallmark of modern anesthesia and intensive care and has been shown to significantly reduce morbidity and mortality in both, lung healthy and injured patients. Beside the use of low tidal volumes, positional therapy has been shown to be associated with beneficial effects.Respiratory resistance and compliance as well as blood gas analysis are routinely used at the bedside but provide only limited information about the regional distribution of ventilation and perfusion. Moreover, imaging modalities such as CT and MRI provide information about the global structure of the lung, but there is limited knowledge about the alveolar dynamic, neither in healthy nor in injured lungs. It is assumed that especially in injured lungs at low pressure, alveoli in gravitationally dependent areas collapse, but this could not be proven by any imaging modality so far. In this proposal, the effects of mechanical ventilation on the structure and function of alveolar tissue will be imaged in vivo in lung healthy and rats with surfactant depletion induced acute lung injury. We will image the same areas of the lung in both, prone and supine position. Presumable there will be changes in alveolar structure and dynamic within the same lung region based on the gravitationally position. Especially in the injured lung, we assume that alveoli will be on average smaller and partly liquid filled.Ventilation parameters such as airway and tissue resistance and compliance will be measured simultaneously with the imaging of alveolar structures and correlated to them. From the combination of alveolar dynamics and lung elasticity, we hope to gain a better understanding for the physiological and pathophysiological processes during mechanical ventilation. Our results will hopefully help the clinician at the bedside to better interpret global lung functional measurements and help to better understand and maybe improve lung protective mechanical ventilation strategies to further reduce morbidity and mortality of mechanically ventilated patients.