理解的对吗？

A widely recognized guide for evaluating lung mechanics, the inspiratory limb of the volume–pressure relationship, was implemented by investigators who proposed setting PEEP 2 cm of water higher than its lower inflection point [7]. This method tacitly assumes that recruitment of viable units is nil at still higher pressures and volumes, and that limited over-distention occurs during tidal ventilation. This misconception motivated research to define and measure recruitment. Unfortunately, the term“recruitment” itself is ambiguous. We and others quantify recruitment through quantitative lung imaging, defining it as the total of gasless tissue regaining aeration. Others assess recruitment as the improved aeration of a predefined lung region [8]. In clinical settings, recruitment has been assumed when tidal compliance increases in response to a PEEP increment [9]. Recruitment estimates measured by improved respiratory mechanics and those quantified by imaging, however, are quitedistinct. In fact, better respiratory mechanics result not only from more numerous aerated units, but also from higher compliance of units already open. Other mechanics-based attempts to identify“best PEEP”, an expiratory intervention, have concentrated on the deflation limb of the volume–pressure relationship.Accordingly, airway pressures were reduced stepwise from endinspiration, with‘best PEEP’ defined as the pressure just above that at which PaO2 or tidal compliance decreased [12]. This method attributes such changes in respiratory system properties to“de-recruitment” within the lung, ignoring its chest wall enclosure. A sharply different approach, one also based on expiratory mechanics (but of the lung itself ), was proposed by Talmor et al. [13]. These authors equated esophageal pressure to pleural pressure and based the elusive“best PEEP” on the level at which the difference between the end-expiratory airway and esophageal pressures turns positive. Apparently, however, doing so offers no clear outcome advantage [14].

据广受认可的肺力学（即容积-压力曲线的吸气肢）评估指南，研究者提出将PEEP的设置为高于容积-压力曲线的吸气肢下拐点2cm。该方法默认在压力和容积仍较高时，非实变肺泡的复张为零，并且在潮气量通气时只有有限的过度膨胀。这种误解激发了定义和衡量“复张”的研究。不幸的是，“复张”一词本身是模棱两可的。我们和其他研究者通过定量肺成像量化肺复张，将其定义为恢复通气的无通气组织的总数。其他研究者将肺复张评估为预先确定的肺区通气改善。在临床，当潮气量顺应性随PEEP增量而增加时，就假设肺复张了。然而，通过改善呼吸力学量化的复张估计值和通过成像量化的复张估计值有很大不同。事实上，改善的呼吸力学不仅因更多的肺通气，还因已通气的肺组织更高的顺应性。其他基于肺力学确定“最佳PEEP”（一种呼气干预）的尝试集中于容量-压力曲线的呼气支。因此，从吸气末开始逐步降低气道压力，“最佳PEEP”定义为略高于PaO2或潮气顺应性降低的PEEP压力。这种确定“最佳PEEP”的方法认为当忽略胸壁时，改变的呼吸系统特性是由于“复张的肺开始塌陷”。Talmor等人提出了一种也是基于呼气力学，但不是基于肺力学的截然不同的方法。这些研究者将食道压等同于胸膜腔压力，将难以捉摸的“最佳PEEP”设定为减去食道压后差值为正的压力。然而，显然，这样做并不能提供明确的预后优势。

the inspiratory limb of the volume–pressure relationship与A widely recognized guide还是与lung mechanics是同位语？

viable非实变？

predefined预先确定的？

tidal compliance潮气顺应性？是不是就是吸气时的肺顺应性？

ignoring its chest wall enclosure 当忽略胸壁时？