Background

Lung rest has been recommended during extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome (ARDS). Whether positive end-expiratory pressure (PEEP) confers lung protection during ECMO for severe ARDS is unclear. We compared the effects of three different PEEP levels whilst applying near-apnoeic ventilation in a model of severe ARDS treated with ECMO.

Methods

Acute respiratory distress syndrome was induced in anaesthetised adult male pigs by repeated saline lavage and injurious ventilation for 1.5 h. After ECMO was commenced, the pigs received standardised near-apnoeic ventilation for 24 h to maintain similar driving pressures and were randomly assigned to PEEP of 0, 10, or 20 cm H₂O (n=7 per group). Respiratory and haemodynamic data were collected throughout the study. Histological injury was assessed by a pathologist masked to PEEP allocation. Lung oedema was estimated by wet-to-dry-weight ratio.

Results

All pigs developed severe ARDS. Oxygenation on ECMO improved with PEEP of 10 or 20 cm H₂O, but did not in pigs allocated to PEEP of 0 cm H₂O. Haemodynamic collapse refractory to norepinephrine (n=4) and early death (n=3) occurred after PEEP 20 cm H₂O. The severity of lung injury was lowest after PEEP of 10 cm H₂O in both dependent and non-dependent lung regions, compared with PEEP of 0 or 20 cm H₂O. A higher wet-to-dry-weight ratio, indicating worse lung injury, was observed with PEEP of 0 cm H₂O. Histological assessment suggested that lung injury was minimised with PEEP of 10 cm H₂O.

Conclusions

During near-apnoeic ventilation and ECMO in experimental severe ARDS, 10 cm H₂O PEEP minimised lung injury and improved gas exchange without compromising haemodynamic stability.

中文翻译：

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体外膜肺氧合和近乎窒息通气治疗实验性急性呼吸窘迫综合征时呼气末正压对肺损伤和血流动力学的影响

背景

对于严重急性呼吸窘迫综合征 (ARDS)，建议在体外膜肺氧合 (ECMO) 期间进行肺休息。呼气末正压 (PEEP) 是否能在 ECMO 期间对严重 ARDS 提供肺保护尚不清楚。我们比较了在 ECMO 治疗的严重 ARDS 模型中应用近乎窒息通气时三种不同 PEEP 水平的影响。

方法

通过反复盐水灌洗和伤害性通气 1.5 小时在麻醉的成年雄性猪中诱发急性呼吸窘迫综合征。开始 ECMO 后，猪接受标准化的近乎窒息通气 24 小时以保持相似的驱动压力，并随机分配到 PEEP 为 0、10 或 20 cm H ₂ O（每组n = 7）。在整个研究过程中收集了呼吸和血流动力学数据。组织学损伤由一名不知道 PEEP 分配情况的病理学家进行评估。通过湿重比估计肺水肿。

结果

所有猪都出现了严重的急性呼吸窘迫综合征。ECMO 上的氧合在 PEEP 为 10 或 20 cm H _{2 O 时得到改善，但在分配到 PEEP 为 0 cm H 2} O的猪中没有改善。去甲肾上腺素难以控制的血流动力学崩溃（n = 4）和早死（n = 3）发生在之后PEEP 20 cm H _{2 O。与 PEEP 0 或 20 cm H 2} O相比，PEEP 10 cm H ₂ O 在依赖和非依赖肺区域的肺损伤严重程度最低。用 0 cm H ₂ O的 PEEP 观察到干重比，表明肺损伤更严重。组织学评估表明，用 10 cm H ₂ O的 PEEP 可以最大限度地减少肺损伤。

结论

在实验性严重 ARDS 的近乎窒息通气和 ECMO 期间，10 cm H ₂ O PEEP 可最大限度地减少肺损伤并改善气体交换，而不会影响血流动力学稳定性。