Pressure support ventilation (PSV) is a form of assisted ventilation which has become frequently used, with the aim of partially unloading the patient’s inspiratory muscles. Both under- and over-assistance should be avoided to target a lung- and diaphragm- protective ventilation. Herein, we propose a conceptual model, supported by actual data, to describe how patient and ventilator share the generation of tidal volume (Vt) in PSV and how respiratory system compliance (Crs) affects this interaction. We describe the presence of a patient-specific range of PSV levels, within which the inspiratory effort (Pmus) is modulated, keeping Vt relatively steady on a desired value (Vttarget). This range of assistance may be considered the “adequate PSV assistance” required by the patient, while higher and lower levels may result in over- and under-assistance respectively. As we also show, the determinants of over- and under- assistance borders depend on the combination of Crs and the inspiratory effort which the patient is able to sustain over a period of time. These concepts can be applied at the bedside to understand if the level of assistance is adequate to patient’s demand, focusing on the variation of relevant parameters (Vt, Pmus and pressure-muscle-index) as patient reaction to a change in the level of assistance.

中文翻译：

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压力支持、患者努力和潮气量：非线互作用的概念模型


压力支持通气 （PSV） 是一种经常使用的辅助通气形式，目的是部分减轻患者的吸气肌负荷。应避免辅助不足和过度辅助，以肺和隔膜保护性通气为目标。在此，我们提出了一个由实际数据支持的概念模型，以描述患者和呼吸机如何共享 PSV 中潮气量 （Vt） 的产生，以及呼吸系统顺应性 （Crs） 如何影响这种相互作用。我们描述了患者特异性 PSV 水平范围的存在，在该范围内，吸气努力 （Pmus） 受到调节，使 Vt 相对稳定在所需值 （Vttarget）。这一范围的援助可能被认为是患者所需的“足够的 PSV 援助”，而更高和更低的水平可能分别导致过度和不足的帮助。正如我们还表明的那样，过度援助和援助不足边界的决定因素取决于 Crs 和患者能够在一段时间内维持的吸气努力的结合。这些概念可以在床边应用，以了解援助水平是否足以满足患者的需求，重点关注相关参数（Vt、Pmus 和压力肌指数）的变化，作为患者对援助水平变化的反应。