Department of Morphology, Surgery and Experimental Medicine, Azienda Ospedaliera-Universitaria Arcispedale Sant'Anna, University of Ferrara, Ferrara, Italy.
Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany.
Crit Care Med. 2020 Aug;48(8):1148-1156. doi: 10.1097/CCM.0000000000004439.
Different techniques exist to select personalized positive end-expiratory pressure in patients affected by the acute respiratory distress syndrome. The positive end-expiratory transpulmonary pressure strategy aims to counteract dorsal lung collapse, whereas electrical impedance tomography could guide positive end-expiratory pressure selection based on optimal homogeneity of ventilation distribution. We compared the physiologic effects of positive end-expiratory pressure guided by electrical impedance tomography versus transpulmonary pressure in patients affected by acute respiratory distress syndrome.
Cross-over prospective physiologic study.
Two academic ICUs.
Twenty ICU patients affected by acute respiratory distress syndrome undergoing mechanical ventilation.
Patients monitored by an esophageal catheter and a 32-electrode electrical impedance tomography monitor underwent two positive end-expiratory pressure titration trials by randomized cross-over design to find the level of positive end-expiratory pressure associated with: 1) positive end-expiratory transpulmonary pressure (PEEPPL) and 2) proportion of poorly or nonventilated lung units (Silent Spaces) less than or equal to 15% (PEEPEIT). Each positive end-expiratory pressure level was maintained for 20 minutes, and afterward, lung mechanics, gas exchange, and electrical impedance tomography data were collected.
PEEPEIT and PEEPPL differed in all patients, and there was no correlation between the levels identified by the two methods (Rs = 0.25; p = 0.29). PEEPEIT determined a more homogeneous distribution of ventilation with a lower percentage of dependent Silent Spaces (p = 0.02), whereas PEEPPL was characterized by lower airway-but not transpulmonary-driving pressure (p = 0.04). PEEPEIT was significantly higher than PEEPPL in subjects with extrapulmonary acute respiratory distress syndrome (p = 0.006), whereas the opposite was true for pulmonary acute respiratory distress syndrome (p = 0.03).
Personalized positive end-expiratory pressure levels selected by electrical impedance tomography- and transpulmonary pressure-based methods are not correlated at the individual patient level. PEEPPL is associated with lower dynamic stress, whereas PEEPEIT may help to optimize lung recruitment and homogeneity of ventilation. The underlying etiology of acute respiratory distress syndrome could deeply influence results from each method.
针对急性呼吸窘迫综合征患者，存在多种选择个体化呼气末正压（positive end-expiratory pressure，PEEP）的技术。跨肺压（positive end-expiratory transpulmonary pressure，PEEPPL）策略旨在对抗背侧肺塌陷，而电阻抗断层成像（electrical impedance tomography，EIT）可基于通气分布的最佳均匀性来指导 PEEP 选择。本研究比较了 EIT 指导与 PEEPPL 指导对急性呼吸窘迫综合征患者的生理学影响。
交叉前瞻性生理学研究。
2 家学术性重症监护病房。
20 例接受机械通气的急性呼吸窘迫综合征患者。
通过食管导管和 32 电极 EIT 监测器监测的患者，采用随机交叉设计进行 2 次 PEEP 滴定试验，以寻找与以下两种情况相关的 PEEP 水平：1）PEEPPL，2）比例小于或等于 15%的非通气或通气不良肺单位（Silent Spaces）（PEEPEIT）。每种 PEEP 水平维持 20 分钟，之后收集肺力学、气体交换和 EIT 数据。
在所有患者中，PEEPEIT 和 PEEPPL 不同，且这两种方法确定的水平之间无相关性（Rs=0.25；p=0.29）。PEEPEIT 可实现通气的更均匀分布，具有更低的依赖 Silent Spaces 百分比（p=0.02），而 PEEPPL 的特征为较低的气道而非跨肺驱动压（p=0.04）。在非肺源性急性呼吸窘迫综合征患者中，PEEPEIT 显著高于 PEEPPL（p=0.006），而在肺源性急性呼吸窘迫综合征患者中则相反（p=0.03）。
EIT 和基于跨肺压的方法确定的个体化 PEEP 水平在个体患者水平上无相关性。PEEPPL 与较低的动态压力相关，而 PEEPEIT 可能有助于优化肺复张和通气的均匀性。急性呼吸窘迫综合征的潜在病因可能会深刻影响每种方法的结果。
