Imaging the Interaction of Atelectasis and Overdistension in Surfactant-Depleted Lungs
Imaging the Interaction of Atelectasis and Overdistension in Surfactant-Depleted Lungs
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DOI：
10.1097/ccm.0b013e31826ab1f2
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发表时间：
2013-02-01
影响因子：
8.8
通讯作者：
Rizi, Rahim R.
中科院分区：
文献类型：
--
作者：
Cereda, Maurizio;Emami, Kiarash;Rizi, Rahim R.
目的：肺不张和表面活性物质耗竭可能导致充气肺区扩大，从而造成损伤；肺不张的恢复可以通过减轻这种过胀来保护这些区域。然而，肺不张（和收缩）对充气空间的影响仍然难以捉摸。我们测试了这样的假设：在机械通气过程中，表面活性剂的耗竭增加了充气空间的尺寸，而肺的重新招募逆转了这些变化。设计：动物模型前瞻性影像学研究。设置：研究成像设施。实验对象：27只健康的Sprague Dawley大鼠。干预措施：麻醉、通气大鼠经生理盐水灌洗获得表面活性剂耗竭。肺泡恢复是通过呼气末正压和外源性表面活性剂来完成的。测量结果及主要结果：采用弥散加权超极化气体磁共振成像技术，测量He-3的表观扩散系数，估算空域尺寸。通过计算机断层扫描和测量氧合来证实肺不张。生理盐水灌洗增加了肺不张（未通气组织从影像面积的1.2%增加到13.8%,p < 0.001），与基线相比，平均表观扩散系数增加（33%,p < 0.001）；ct信号的非均质性和表观扩散系数的方差增大。呼气末正压和表面活性剂的应用降低了平均表观扩散系数（23%,p < 0.001）及其方差，与肺泡恢复平行（即减少计算机断层扫描密度和异质性，增加氧合）。结论：应用临床相关磁共振成像技术可检测到肺不张时通气肺的过度扩张，这可能是机械通气时肺损伤发生的关键因素。通过较高的呼气末正压和表面活性剂的使用来增加肺功能，可以减少空气空间的扩张。（中国医学快报2013；41:527-535）
Objective: Atelectasis and surfactant depletion may contribute to greater distension-and thereby injury-of aerated lung regions; recruitment of atelectatic lung may protect these regions by attenuating such overdistension. However, the effects of atelectasis (and recruitment) on aerated airspaces remain elusive. We tested the hypothesis that during mechanical ventilation, surfactant depletion increases the dimensions of aerated airspaces and that lung recruitment reverses these changes.Design: Prospective imaging study in an animal model.Setting: Research imaging facility.Subjects: Twenty-seven healthy Sprague Dawley rats.Interventions: Surfactant depletion was obtained by saline lavage in anesthetized, ventilated rats. Alveolar recruitment was accomplished using positive end-expiratory pressure and exogenous surfactant administration.Measurements and Main Results: Airspace dimensions were estimated by measuring the apparent diffusion coefficient of He-3, using diffusion-weighted hyperpolarized gas magnetic resonance imaging. Atelectasis was demonstrated using computerized tomography and by measuring oxygenation. Saline lavage increased atelectasis (increase in nonaerated tissue from 1.2% to 13.8% of imaged area, p < 0.001), and produced a concomitant increase in mean apparent diffusion coefficient ( 33%, p < 0.001) vs. baseline; the heterogeneity of the computerized tomography signal and the variance of apparent diffusion coefficient were also increased. Application of positive end-expiratory pressure and surfactant reduced the mean apparent diffusion coefficient ( 23%, p < 0.001), and its variance, in parallel to alveolar recruitment (i. e., less computerized tomography densities and heterogeneity, increased oxygenation).Conclusions: Overdistension of aerated lung occurs during atelectasis is detectable using clinically relevant magnetic resonance imaging technology, and could be a key factor in the generation of lung injury during mechanical ventilation. Lung recruitment by higher positive end-expiratory pressure and surfactant administration reduces airspace distension. (Crit Care Med 2013; 41: 527-535)