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[Blue Journal在线发表]:容量控制通气不能预防自主呼吸时的肺损伤
2017年04月09日 时讯速递, 进展交流 暂无评论

Volume Controlled Ventilation does not Prevent Injurious Inflation during Spontaneous Effort

Takeshi Yoshida, Susumu Nakahashi, Maria Aparecida Miyuki Nakamura, et al

Am J Respir Crit Care Med 2017

Published on 17-February-2017 as 10.1164/rccm.201610-1972OC

Rationale: 背景

Spontaneous breathing during mechanical ventilation increases transpulmonary pressure and tidal volume, and worsens lung injury. Intuitively, controlling tidal volume and transpulmonary pressure might limit injury from added spontaneous effort.

机械通气时的自主呼吸能够增加跨肺压和潮气量,加重肺损伤。控制潮气量和跨肺压可能防止自主呼吸引起的损伤。

Objectives: 目的

To test the hypothesis that during spontaneous effort in injured lungs, tidal volume and transpulmonary pressure limitation by volume-controlled ventilation results in less injurious patterns of inflation.

验证如下假设:即损伤肺在自主呼吸情况下,通过容量控制通气限制潮气量和跨肺压能够减少充气过程造成的损伤。

Methods: 方法

Dynamic CT was used to determine patterns of regional inflation in rabbits, in injured lungs, during volume-controlled or pressure-controlled ventilation. Transpulmonary pressure was estimated by using esophageal balloon manometry (PL(es)) with and without spontaneous effort. Local dependent lung stress was estimated as the swing (inspiratory change) in transpulmonary pressure measured by intra-pleural manometry in dependent lung (ΔPL(dep)) and was compared with ΔPL(es). Electrical impedance tomography evaluated the inflation pattern in a larger animal (pig) and in a patient with ARDS.

动态CT用于确定容量控制通气或压力控制通气下家兔损伤肺局部充气情况。留置食道气囊导管测定有无自主呼吸情况下的跨肺压(PL(es))。根据重力依赖区域胸腔内导管测定的跨肺压波动(吸气改变)(ΔPL(dep))估测局部肺应力,并与ΔPL(es)进行比较。采用电阻抗CT评价大动物(猪)及一名ARDS患者的充气情况。

Measurements and Main Results: 测定和主要结果

Spontaneous breathing in injured lungs increased PL(es) during pressure-controlled (but not volume-controlled) ventilation, but the pattern of dependent lung inflation was the same in both modes. In volume-controlled ventilation, spontaneous effort caused greater inflation and tidal recruitment of dorsal regions (>2-fold) vs. during muscle paralysis, despite the same tidal volume and PL(es). This was caused by higher local lung stress, ΔPL(dep). In injured lungs, esophageal manometry underestimated local dependent pleural pressure changes during spontaneous effort.

在压力控制通气(而非容量控制通气)时,自主呼吸能够增加损伤肺的PL(es),但两种模式下重力依赖区域充气情况相似。在容量控制通气时,与肌松相比,尽管潮气量及PL(es)相似,自主呼吸导致背侧区域充气及潮式复张更为明显(> 2倍)。这是局部肺应力ΔPL(dep)更高的结果。对于损伤肺,食道压力测定低估自主呼吸时重力依赖区域胸腔内压改变。

Conclusions: 结论

Limitation of tidal volume and PL(es) by volume-controlled ventilation could not eliminate harm from spontaneous breathing, unless the level of spontaneous effort was lowered and local dependent lung stress was reduced.

通过容量控制通气限制潮气量和PL(dep)不能消除自主呼吸的危害,除非减弱自主呼吸的水平从而减少重力依赖区域肺应力。

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