Lung Stress and Strain During Mechanical Ventilation: Any Difference Between Statics and Dynamics?
Lung Stress and Strain During Mechanical Ventilation: Any Difference Between Statics and Dynamics?
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DOI：
10.1097/ccm.0b013e31827417a6
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发表时间：
2013-04-01
影响因子：
8.8
通讯作者：
Gattinoni, Luciano
中科院分区：
文献类型：
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作者：
Protti, Alessandro;Andreis, Davide T.;Gattinoni, Luciano
目的：潮气量 (V-T) 和呼气末正压 (V-PEEP) 引起的气体量分别产生动态和静态肺应变。我们的目的是澄清动态和静态应变的不同组合是否会导致相同的大的整体应变，不断产生肺水肿。设计：实验室调查。设置：动物单位。受试者：28头健康猪。干预：肺部计算机断层扫描后，20只动物在2.5的整体应变下通气54小时，要么完全动态（V-T 100%和V-PEEP 0%），部分动态和 部分静态（V-T 75-50% 和 V-PEEP 25-50%），或主要静态（V-T 25% 和 V-PEEP 75%），然后被杀死。在其他八头猪中（V-T 25% 和 V-PEEP 75%），V-PEEP 在 36-54 小时后突然为零，并持续通气 3 小时。 测量和主要结果：当最终肺重量（平衡）超过初始重量（计算机断层扫描）时，诊断出水肿。评估了死亡率、肺力学、气体交换、肺组织学和炎症。所有以完全动态应变 (V-T 825 +/- 424 mL) 通气的动物均出现肺水肿（肺重量从 334 +/- 38 至 658 +/- 99 g，p < 0.01），而所有以主要静态应变（V-T 237 +/- 21 mL 和 V-PEEP 906 +/- 114 mL，对应于 19 +/- 1 cm）通气的动物均未出现肺水肿。水分子的 呼气末正压）确实如此（从 314 +/- 55 到 277 +/- 46 g，p = 0.65）。采用中间组合通气的动物最终肺重量正常或大幅增加。较小的动态应变和较大的静态应变可降低死亡率 (p < 0.01)、肺力学紊乱 (p < 0.01) 和动脉氧合 (p < 0.01)、组织学损伤评分 (p = 0.03) 和支气管肺泡白细胞介素 6 浓度 (p < 0.01)。去除呼气末正压不会导致肺重量突然增加（从 336 +/- 36 到 351 +/- 77 g，p = 0.51）。结论：肺水肿的形成（可能是全或无反应）不仅取决于整体应变，还取决于其组成部分。大静态应变比大动态应变危害更小，但这并不是因为前者仅仅抵消液体外渗。 （《重症监护医学》2013 年；41：1046-1055）
Objective: Tidal volume (V-T) and volume of gas caused by positive end-expiratory pressure (V-PEEP) generate dynamic and static lung strains, respectively. Our aim was to clarify whether different combinations of dynamic and static strains, resulting in the same large global strain, constantly produce lung edema.Design: Laboratory investigation.Setting: Animal unit.Subjects: Twenty-eight healthy pigs.Interventions: After lung computed tomography, 20 animals were ventilated for 54 hours at a global strain of 2.5, either entirely dynamic (V-T 100% and V-PEEP 0%), partly dynamic and partly static (V-T 75-50% and V-PEEP 25-50%), or mainly static (V-T 25% and V-PEEP 75%) and then killed. In eight other pigs (V-T 25% and V-PEEP 75%), V-PEEP was abruptly zeroed after 36-54 hours and ventilation continued for 3 hours.Measurements and Main Results: Edema was diagnosed when final lung weight (balance) exceeded the initial weight (computed tomography). Mortality, lung mechanics, gas exchange, pulmonary histology, and inflammation were evaluated. All animals ventilated with entirely dynamic strain (V-T 825 +/- 424 mL) developed pulmonary edema (lung weight from 334 +/- 38 to 658 +/- 99 g, p < 0.01), whereas none of those ventilated with mainly static strain (V-T 237 +/- 21 mL and V-PEEP 906 +/- 114 mL, corresponding to 19 +/- 1 cm H2O of positive end-expiratory pressure) did (from 314 +/- 55 to 277 +/- 46 g, p = 0.65). Animals ventilated with intermediate combinations finally had normal or largely increased lung weight. Smaller dynamic and larger static strains lowered mortality (p < 0.01), derangement of lung mechanics (p < 0.01), and arterial oxygenation (p < 0.01), histological injury score (p = 0.03), and bronchoalveolar interleukin-6 concentration (p < 0.01). Removal of positive end-expiratory pressure did not result in abrupt increase in lung weight (from 336 +/- 36 to 351 +/- 77 g, p = 0.51).Conclusions: Lung edema forms (possibly as an all-or-none response) depending not only on global strain but also on its components. Large static are less harmful than large dynamic strains, but not because the former merely counteracts fluid extravasation. (Crit Care Med 2013; 41: 1046-1055)