Lung Stress and Strain during Mechanical Ventilation Any Safe Threshold?
Lung Stress and Strain during Mechanical Ventilation Any Safe Threshold?
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DOI：
10.1164/rccm.201010-1757oc
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发表时间：
2011-05-15
影响因子：
24.7
通讯作者：
Gattinoni, Luciano
中科院分区：
文献类型：
--
作者：
Protti, Alessandro;Cressoni, Massimo;Gattinoni, Luciano
基本原理：非生理性应变（潮气量和功能残气量之间的比率）和应力（transulpture压力）可以导致呼吸机引起的肺damage.Objectives：为了确定一个应变应力阈值（如果有的话）高于呼吸机引起的肺damage.Methods：29只健康猪机械通气54小时，潮气量产生的应变在0.45和3.30之间。呼吸机引起的肺损伤被定义为净增加肺weight. Measures和主要结果：初始肺重量和功能残气量进行了测量与计算机断层扫描。使用天平测量最终肺重量。设定潮气量后，数据收集包括呼吸系统力学、气体交换和血流动力学（每6小时）;血清（每12小时）和支气管肺泡灌洗液（实验结束）中的细胞因子水平;以及血液实验室检查（实验开始和结束）。可以清楚地识别两组动物：肺重量增加的动物（n = 14）和肺重量未增加的动物（n = 15）。前一组的潮气量为38 +/- 9 ml/kg，后一组为22 +/- 8 ml/kg，分别对应于2.16 +/- 0.58和1.29 +/- 0.57的应变和13 +/- 5和8 +/- 3 cm H2O的应力。肺增重与呼吸系统力学，气体交换，血流动力学，肺部和全身炎症和多器官功能障碍恶化。结论：在健康的猪，呼吸机引起的肺损伤的发展，只有当应变大于1.5-2达到或克服。由于内在肺特性的差异，在将这些发现转化为人类时需要谨慎。
Rationale: Unphysiologic strain (the ratio between tidal volume and functional residual capacity) and stress (the transpulmonary pressure) can cause ventilator-induced lung damage.Objectives: To identify a strain-stress threshold (if any) above which ventilator-induced lung damage can occur.Methods: Twenty-nine healthy pigs were mechanically ventilated for 54 hours with a tidal volume producing a strain between 0.45 and 3.30. Ventilator-induced lung damage was defined as net increase in lung weight.Measurements and Main Results: Initial lung weight and functional residual capacity were measured with computed tomography. Final lung weight was measured using a balance. After setting tidal volume, data collection included respiratory system mechanics, gas exchange and hemodynamics (every 6 h); cytokine levels in serum (every 12 h) and bronchoalveolar lavage fluid (end of the experiment); and blood laboratory examination (start and end of the experiment). Two clusters of animals could be clearly identified: animals that increased their lung weight (n = 14) and those that did not (n = 15). Tidal volume was 38 +/- 9 ml/kg in the former and 22 +/- 8 ml/kg in the latter group, corresponding to a strain of 2.16 +/- 0.58 and 1.29 +/- 0.57 and a stress of 13 +/- 5 and 8 +/- 3 cm H2O, respectively. Lung weight gain was associated with deterioration in respiratory system mechanics, gas exchange, and hemodynamics, pulmonary and systemic inflammation and multiple organ dysfunction.Conclusions: In healthy pigs, ventilator-induced lung damage develops only when a strain greater than 1.5-2 is reached or overcome. Because of differences in intrinsic lung properties, caution is warranted in translating these findings to humans.