BACKGROUND Mechanical ventilation with variable tidal volumes (VT) may improve lung function and reduce ventilator-induced lung injury in experimental acute respiratory distress syndrome (ARDS). However, previous investigations were limited to less than 6 h, and control groups did not follow clinical standards. We hypothesised that 24 h of mechanical ventilation with variable VT reduces pulmonary inflammation (as reflected by neutrophil infiltration), compared with standard protective, nonvariable ventilation. METHODS Experimental ARDS was induced in 14 anaesthetised pigs with saline lung lavage followed by injurious mechanical ventilation. Pigs (n=7 per group) were randomly assigned to using variable VT or nonvariable VT modes of mechanical ventilation for 24 h. In both groups, ventilator settings including positive end-expiratory pressure and oxygen inspiratory fraction were adjusted according to the ARDS Network protocol. Pulmonary inflammation (primary endpoint) and perfusion were assessed by positron emission tomography using 2-deoxy-2-[18F]fluoro-d-glucose and 68Gallium (68Ga)-labelled microspheres, respectively. Gas exchange, respiratory mechanics, and haemodynamics were quantified. Lung aeration was determined using CT. RESULTS The specific global uptake rate of 18F-FDG increased to a similar extent regardless of mode of mechanical ventilation (median uptake for variable VT=0.016 min-1 [inter-quartile range, 0.012-0.029] compared with median uptake for nonvariable VT=0.037 min-1 [0.008-0.053]; P=0.406). Gas exchange, respiratory mechanics, haemodynamics, and lung aeration and perfusion were similar in both variable and nonvariable VT ventilatory modes. CONCLUSION In a porcine model of ARDS, 24 h of mechanical ventilation with variable VT did not attenuate pulmonary inflammation compared with standard protective mechanical ventilation with nonvariable VT.

中文翻译：

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可变与非可变控制机械通气对实验性急性呼吸窘迫综合征猪肺部炎症的影响。


背景技术可变潮气量（VT）机械通气可以改善实验性急性呼吸窘迫综合征（ARDS）中的肺功能并减少呼吸机引起的肺损伤。然而，之前的调查仅限于6小时以内，对照组没有遵循临床标准。我们假设，与标准保护性非可变通气相比，24 小时可变 VT 机械通气可减少肺部炎症（如中性粒细胞浸润所反映）。方法 对 14 只麻醉猪进行实验性 ARDS，先用盐水进行肺灌洗，然后进行损伤性机械通气。猪（每组 n=7）被随机分配使用可变 VT 或非可变 VT 模式机械通气 24 小时。在两组中，呼吸机设置（包括呼气末正压和吸氧分数）均根据 ARDS 网络协议进行调整。分别使用 2-脱氧-2-[18F]氟-d-葡萄糖和 68 镓 (68Ga) 标记微球通过正电子发射断层扫描评估肺部炎症（主要终点）和灌注。气体交换、呼吸力学和血流动力学被量化。使用 CT 确定肺通气量。结果 无论机械通气模式如何， 18F-FDG 的特定总体摄取率均增加到类似程度（与非可变 VT= 的中位摄取相比，可变 VT=0.016 min-1 [四分位数范围，0.012-0.029] 的中位摄取） 0.037 分钟-1 [0.008-0.053]；P=0.406)。在可变和非可变 VT 通气模式下，气体交换、呼吸力学、血流动力学以及肺通气和灌注相似。 结论 在猪 ARDS 模型中，与标准保护性机械通气（不可变 VT）相比，24 小时可变 VT 机械通气并不能减轻肺部炎症。