Mechanical Power and Ventilator-induced Lung Injury: What Does Physics Have to Say?
Mechanical Power and Ventilator-induced Lung Injury: What Does Physics Have to Say?
复制标题
机械功率和呼吸机引起的肺损伤：物理学有什么说法？
DOI：
10.1164/rccm.202307-1292vp
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发表时间：
2023
影响因子：
24.7
通讯作者：
Gaver III, Donald P
中科院分区：
文献类型：
--
作者：
Bates, Jason H.T.;Kaczka, David W.;Kollisch-Singule, Michaela;Nieman, Gary F;Gaver III, Donald P
呼吸机诱导的肺损伤（VILI）是一个潜在的威胁，任何人接受支持性机械通气急性呼吸衰竭。然而，尽管经过数十年的研究，对特定患者进行手术的最安全方法仍然存在争议。这为新概念提供了肥沃的土壤，最近出现的一个概念是呼吸机向肺部提供潜在的破坏性机械能（1，2）。这个概念的动机很清楚：当任何结构受到物理损坏时，都会涉及能量转移。因此，通过呼吸机向肺部输送能量（即机械功率）的速率应该与VILI相关，这可能是直观的。然而，理解机械功率和VILI之间的关系需要明确存储能量与耗散能量之间的差异，无论通气是由气道开口处的正压还是胸膜腔中的负压引起的[3]。当呼吸机使肺膨胀时，一些施加的功作为弹性势能存储在肺组织中。这种类型的能量是物理学家所说的保守的，这意味着它是完全可恢复的。只有当吸气时变形的组织在呼气时精确地恢复到其充气前的形态时，才会出现这种情况。对组织的净结果相当于能量从一开始就没有被输送。
Ventilator-induced lung injury (VILI) is a potential threat to anyone receiving supportive mechanical ventilation for acute respiratory failure. Despite decades of research, however, the safest way to ventilate any given patient remains controversial. This makes fertile ground for novel concepts, and one that has arisen recently concerns the idea that a ventilator imparts potentially damaging mechanical energy to the lungs (1, 2). The motivation for this concept is clear: Energy transfer is involved when any structure becomes physically damaged. It may be intuitive, then, that the rate at which energy is delivered to the lungs by a ventilator—namely, mechanical power—should be associated with VILI. Nevertheless, understanding the relationship between mechanical power and VILI requires clarity on the difference between stored versus dissipated energy, regardless of whether ventilation is caused by positive pressure at the airway opening or negative pressure in the pleural space (3).When a ventilator inflates the lung, some of the applied work is stored in the lung tissues as elastic potential energy. This type of energy is what physicists call conservative, meaning it is completely recoverable. This can only be the case if those tissues that become distorted during inspiration are returned precisely to their preinflation configurations on expiration. The net result to the tissues is equivalent to the energy never having been delivered in the first place.