Stenqvist Ola, Persson Per, Lundin Stefan
Department of Anesthesiology and Intensive Care Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
Ann Transl Med. 2018 Oct;6(19):392. doi: 10.21037/atm.2018.06.05.
A protective ventilation strategy is based on separation of lung and chest wall mechanics and determination of transpulmonary pressure. So far, this has required esophageal pressure measurement, which is cumbersome, rarely used clinically and associated with lack of consensus on the interpretation of measurements. We have developed an alternative method based on a positive end expiratory pressure (PEEP) step procedure where the PEEP-induced change in end-expiratory lung volume is determined by the ventilator pneumotachograph. In pigs, lung healthy patients and acute lung injury (ALI) patients, it has been verified that the determinants of the change in end-expiratory lung volume following a PEEP change are the size of the PEEP step and the elastic properties of the lung, ∆PEEP × Clung. As a consequence, lung compliance can be calculated as the change in end-expiratory lung volume divided by the change in PEEP and esophageal pressure measurements are not needed. When lung compliance is determined in this way, transpulmonary driving pressure can be calculated on a breath-by-breath basis. As the end-expiratory transpulmonary pressure increases as much as PEEP is increased, it is also possible to determine the end-inspiratory transpulmonary pressure at any PEEP level. Thus, the most crucial factors of ventilator induced lung injury can be determined by a simple PEEP step procedure. The measurement procedure can be repeated with short intervals, which makes it possible to follow the course of the lung disease closely. By the PEEP step procedure we may also obtain information (decision support) on the mechanical consequences of changes in PEEP and tidal volume performed to improve oxygenation and/or carbon dioxide removal.
保护性通气策略基于肺与胸壁力学的分离以及跨肺压的测定。到目前为止，这需要测量食管压力，该方法操作繁琐，临床很少使用，且在测量结果的解读上缺乏共识。我们开发了一种基于呼气末正压（PEEP）阶梯程序的替代方法，其中呼气末肺容积因PEEP引起的变化由呼吸机呼吸流速仪测定。在猪、肺部健康患者和急性肺损伤（ALI）患者中，已经证实PEEP变化后呼气末肺容积变化的决定因素是PEEP阶梯的大小和肺的弹性特性，即∆PEEP×肺顺应性（Clung）。因此，可以通过呼气末肺容积的变化除以PEEP的变化来计算肺顺应性，而无需测量食管压力。当以这种方式测定肺顺应性时，可以逐次计算跨肺驱动压力。由于呼气末跨肺压随着PEEP的增加而增加，因此也可以在任何PEEP水平下确定吸气末跨肺压。因此，通过简单的PEEP阶梯程序就可以确定呼吸机诱导性肺损伤的最关键因素。测量程序可以短时间间隔重复进行，这使得密切跟踪肺部疾病的进程成为可能。通过PEEP阶梯程序，我们还可以获得关于为改善氧合和/或二氧化碳清除而改变PEEP和潮气量的机械后果的信息（决策支持）。
