Maggiore S M, Richard J C, Brochard L
Dept of Anaesthesiology and Intensive Care, Agostino Gemelli Hospital, Università Cattolica del Sacro Cuore, Rome, Italy.
Eur Respir J Suppl. 2003 Aug;42:22s-26s. doi: 10.1183/09031936.03.00004204.
Mechanical impairment of the respiratory system was recognised soon after the description of acute respiratory distress syndrome. The analysis of the pressure/volume (P/V) curve of the respiratory system contributed a lot to the understanding of the pathophysiology of acute lung injury and formed the basis for lung protection. The lower and upper inflection points were regarded as points of interest to avoid cyclic derecruitment and overdistension and to optimise ventilatory settings. However, because of the heterogeneity of lung injury, reducing the mechanical properties of the whole respiratory system to a single curve is a schematic approach, which makes interpretation difficult. New data suggest that alveolar re-inflation occurs along the whole P/V curve that can, therefore, be considered as a recruitment curve. The lower inflection point has no relationship with alveolar opening and closure and does not indicate the positive end-expiratory pressure needed to prevent alveolar collapse. The shape of the P/V curve gives information about the extension and the homogeneity of lung injury, indicating the possibility of lung recruitment. The upper inflection point, classically seen as the beginning of overdistension, may also indicate the end of recruitment. The pressure/volume curve offers the unique opportunity of evaluating alveolar recruitment/derecruitment at the bedside that can be helpful for the identification of optimal ventilatory settings and makes the curve a valuable tool for the ventilatory management of acute lung injury.
在急性呼吸窘迫综合征被描述后不久，人们就认识到了呼吸系统的机械性损伤。呼吸系统压力/容积（P/V）曲线的分析对理解急性肺损伤的病理生理学有很大帮助，并构成了肺保护的基础。下拐点和上拐点被视为避免周期性肺不张和过度扩张以及优化通气设置的关注点。然而，由于肺损伤的异质性，将整个呼吸系统的力学特性简化为一条单一曲线是一种示意性方法，这使得解读变得困难。新数据表明，肺泡再膨胀沿着整个P/V曲线发生，因此该曲线可被视为一条复张曲线。下拐点与肺泡的开放和关闭无关，也不表明预防肺泡塌陷所需的呼气末正压。P/V曲线的形状提供了有关肺损伤范围和同质性的信息，表明了肺复张的可能性。传统上被视为过度扩张开始的上拐点，也可能表明复张的结束。压力/容积曲线提供了在床边评估肺泡复张/肺不张的独特机会，这有助于确定最佳通气设置，并使该曲线成为急性肺损伤通气管理的有价值工具。
