van Egmond Jan, Booij Leo H D J
Department of Anesthesiology, Radboud University Medical Centre, Nijmegen, The Netherlands.
Donders Institute for Brain, Cognition and Behaviour, Donders Centre for Cognition, Radboud University Nijmegen, Nijmegen, The Netherlands.
J Thorac Dis. 2024 Nov 30;16(11):8103-8109. doi: 10.21037/jtd-24-497. Epub 2024 Nov 18.
Mechanical ventilation, essential for critically ill patients, contrasts with natural respiration, primarily due to differences in pleural pressure ( ). Natural inspiration decreases , pulling the lungs away from the thoracic wall, whereas positive pressure inspiration increases , pushing the lungs against the thoracic wall. This shift has several consequences. First, elevated during positive pressure ventilation can lead to cyclic airway closure, particularly in the dependent lung regions. This increases the risk of atelectasis, that impairs oxygenation and may lead to further complications such as pneumonia. Second, the increase in disrupts the balance maintained by negative and capillary forces. This disruption reduces the lubricating pleural fluid between the pleurae, increasing friction and shear stress on the lung tissues, which may lead to damage and conditions such as ventilator-induced lung injury and pneumothorax. Furthermore, airway closure can worsen lung compliance, making mechanical ventilation more challenging and increasing the risk of lung overstretching. This necessitates careful management of ventilation settings, particularly the use of positive end-expiratory pressure (PEEP) and recruitment maneuvers to minimize these adverse effects. Protective strategies, such as synchronizing mechanical ventilation with the patient's breathing efforts, prone positioning, and careful application of PEEP, are crucial in reducing and its associated risks. Since negative pressure ventilation (NPV) inherently lowers , it may help avoid many of the adverse side effects previously discussed. Therefore, reconsidering and reintroducing NPV in a modern context should be seriously explored.
机械通气对重症患者至关重要，它与自然呼吸形成对比，主要是由于胸膜压力存在差异。自然吸气时胸膜压力降低，将肺拉离胸壁，而正压吸气时胸膜压力升高，将肺压向胸壁。这种变化会产生多种后果。首先，正压通气时胸膜压力升高会导致气道周期性关闭，尤其是在肺低垂区域。这增加了肺不张的风险，肺不张会损害氧合，并可能导致诸如肺炎等进一步并发症。其次，胸膜压力升高会破坏由负压和毛细血管力维持的平衡。这种破坏会减少胸膜之间起润滑作用的胸膜液，增加肺组织上的摩擦力和剪切应力，这可能导致损伤以及诸如呼吸机相关性肺损伤和气胸等情况。此外，气道关闭会使肺顺应性恶化，使机械通气更具挑战性，并增加肺过度伸展的风险。这就需要仔细管理通气设置，特别是使用呼气末正压（PEEP）和肺复张手法以尽量减少这些不良影响。保护性策略，如使机械通气与患者的呼吸努力同步、采用俯卧位以及谨慎应用PEEP，对于降低胸膜压力及其相关风险至关重要。由于负压通气（NPV）本质上会降低胸膜压力，它可能有助于避免前面讨论的许多不良副作用。因此，应认真探索在现代背景下重新考虑和重新引入负压通气。
