From the Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany (LV, RH, AB, MS, JW, TK, PH, MH, MM, MGA, TB), Department of Pathophysiology and Transplantation, University of Milan, Italy (LV), Institute of Nuclear Medicine, University Hospital Carl Gustav Carus, Dresden (AB), Department of Anesthesiology, Elblandklinikum Radebeul, Radebeul (TK), Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe (MK), Drägerwerk AG & Co KGaA, Lübeck, Germany (MK), IRCCS San Martino IST, Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy (MM), Department of Intensive Care and Resuscitation (MGA) and Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio, USA (MGA).
Eur J Anaesthesiol. 2023 Jul 1;40(7):501-510. doi: 10.1097/EJA.0000000000001808. Epub 2023 Feb 22.
Variable ventilation recruits alveoli in atelectatic lungs, but it is unknown how it compares with conventional recruitment manoeuvres.
To test whether mechanical ventilation with variable tidal volumes and conventional recruitment manoeuvres have comparable effects on lung function.
Randomised crossover study.
University hospital research facility.
Eleven juvenile mechanically ventilated pigs with atelectasis created by saline lung lavage.
Lung recruitment was performed using two strategies, both with an individualised optimal positive-end expiratory pressure (PEEP) associated with the best respiratory system elastance during a decremental PEEP trial: conventional recruitment manoeuvres (stepwise increase of PEEP) in pressure-controlled mode) followed by 50 min of volume-controlled ventilation (VCV) with constant tidal volume, and variable ventilation, consisting of 50 min of VCV with random variation in tidal volume.
Before and 50 min after each recruitment manoeuvre strategy, lung aeration was assessed by computed tomography, and relative lung perfusion and ventilation (0% = dorsal, 100% = ventral) were determined by electrical impedance tomography.
After 50 min, variable ventilation and stepwise recruitment manoeuvres decreased the relative mass of poorly and nonaerated lung tissue (percent lung mass: 35.3 ± 6.2 versus 34.2 ± 6.6, P = 0.303); reduced poorly aerated lung mass compared with baseline (-3.5 ± 4.0%, P = 0.016, and -5.2 ± 2.8%, P < 0.001, respectively), and reduced nonaerated lung mass compared with baseline (-7.2 ± 2.5%, P < 0.001; and -4.7 ± 2.8%, P < 0.001 respectively), while the distribution of relative perfusion was barely affected (variable ventilation: -0.8 ± 1.1%, P = 0.044; stepwise recruitment manoeuvres: -0.4 ± 0.9%, P = 0.167). Compared with baseline, variable ventilation and stepwise recruitment manoeuvres increased Pa O 2 (172 ± 85mmHg, P = 0.001; and 213 ± 73 mmHg, P < 0.001, respectively), reduced Pa CO 2 (-9.6 ± 8.1 mmHg, P = 0.003; and -6.7 ± 4.6 mmHg, P < 0.001, respectively), and decreased elastance (-11.4 ± 6.3 cmH 2 O, P < 0.001; and -14.1 ± 3.3 cmH 2 O, P < 0.001, respectively). Mean arterial pressure decreased during stepwise recruitment manoeuvres (-24 ± 8 mmHg, P = 0.006), but not variable ventilation.
In this model of lung atelectasis, variable ventilation and stepwise recruitment manoeuvres effectively recruited lungs, but only variable ventilation did not adversely affect haemodynamics.
This study was registered and approved by Landesdirektion Dresden, Germany (DD24-5131/354/64).
可变潮气量通气可募集肺不张肺泡，但尚不清楚其与传统的复张手法相比效果如何。
比较机械通气时采用可变潮气量与传统复张手法对肺功能的影响。
随机交叉研究。
大学医院研究设施。
通过盐水肺灌洗造成肺不张的 11 头幼猪。
采用两种策略进行肺复张，均采用个体化最佳呼气末正压（PEEP），与递减 PEEP 试验中最佳呼吸系统顺应性相关：压力控制模式下的传统复张手法（逐步增加 PEEP），随后 50 分钟容量控制通气（VCV），恒定潮气量，以及可变通气，由 50 分钟随机变化的 VCV 组成。
在每种复张策略前后 50 分钟，通过计算机断层扫描评估肺充气情况，通过电阻抗断层成像测定相对肺灌注和通气（0%=背部，100%=腹部）。
50 分钟后，可变通气和逐步复张手法降低了肺不张和非充气组织的相对质量（肺质量百分比：35.3±6.2 对 34.2±6.6，P=0.303）；与基线相比，减少了不张肺组织的质量（分别减少了 3.5±4.0%，P=0.016，和 5.2±2.8%，P<0.001），并减少了非充气肺组织的质量（分别减少了 7.2±2.5%，P<0.001；和 4.7±2.8%，P<0.001），而相对灌注分布几乎没有受到影响（可变通气：-0.8±1.1%，P=0.044；逐步复张手法：-0.4±0.9%，P=0.167）。与基线相比，可变通气和逐步复张手法增加了 PaO 2（172±85mmHg，P=0.001；和 213±73mmHg，P<0.001），降低了 PaCO 2（-9.6±8.1mmHg，P=0.003；和-6.7±4.6mmHg，P<0.001），并降低了弹性（-11.4±6.3cmH 2 O，P<0.001；和-14.1±3.3cmH 2 O，P<0.001）。逐步复张手法期间平均动脉压下降（-24±8mmHg，P=0.006），但可变通气没有。
在这种肺不张模型中，可变通气和逐步复张手法可有效地募集肺，但只有可变通气不会对血液动力学产生不利影响。
本研究在德国德累斯顿地区局（DD24-5131/354/64）进行了注册和批准。
