A linearized expiration flow homogenizes the compartmental pressure distribution in a physical model of the inhomogeneous respiratory system
A linearized expiration flow homogenizes the compartmental pressure distribution in a physical model of the inhomogeneous respiratory system
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DOI：
10.1088/1361-6579/ab83e6
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发表时间：
2020-04-01
影响因子：
3.2
通讯作者：
Schumann, Stefan
中科院分区：
文献类型：
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作者：
Wenzel, Christin;Frey, Carina;Schumann, Stefan
目的：流量控制呼气（FLEX）和流量控制通气（FCV）意味着线性呼气，被认为是肺保护性通气的新途径，特别是在肺不均匀的情况下。我们假设，与容量控制通气（VCV）和压力控制通气（PCV）相比，线性化通气使通气期间各隔室之间的压力分布均匀。方法：我们在一个非均匀呼吸系统的物理模型中研究了呼气压衰减。该模型包含四个腔室，其中两个具有高依从性(25 ml cmH(2)O(-1))，两个具有低依从性(10 ml cmH（2)O(-1)）。这些分别与高电阻(6.5 cmH（2)O s l(-1)）或低电阻(2.8 cmH（2)O s l(-1)）结合。在不同的潮气量和峰值压力下，以所有模式对模型进行通气，我们确定了每个室中压力下降到吸气末压力的50% （t(50)）的呼气时间，以及所有室之间t(50) （δ t(50)）和压力（δ p(max)）的最大差异。主要结果：在FLEX和FCV期间，t（50）比VCV和PCV高6- 7倍（均P < 0.001）。在VCV和PCV期间，δ t（50）高于FLEX和FCV (49 +/- 19 ms，均P < 0.001) （128 +/- 18 ms）。VCV和PCV期间δ p（max）可达3.8 +/- 0.2 cmH(2)O，而FLEX和FCV期间δ p（max）仅为0.6 +/- 0.1 cmH(2)O （p < 0.001）。意义：与VCV和PCV相比，FLEX和FCV在不同力学性能的隔室之间提供了更均匀的呼气压力分布。这可以减少不均匀肺组织内的剪切应力。
Objective: Flow-controlled expiration (FLEX) and flow-controlled ventilation (FCV) imply a linearized expiration, and were suggested as new approaches for lung-protective ventilation, especially in the case of an inhomogeneous lung. We hypothesized that a linearized expiration homogenizes the pressure distribution between compartments during expiration, compared to volume-controlled (VCV) and pressure-controlled (PCV) ventilation. Approach: We investigated the expiratory pressure decays in a physical model of an inhomogeneous respiratory system. The model contained four compartments of which two had a high (25 ml cmH(2)O(-1)) and two a low compliance (10 ml cmH(2)O(-1)). These were combined with either a high (6.5 cmH(2)O s l(-1)) or low resistance (2.8 cmH(2)O s l(-1)), respectively. The model was ventilated in all modes at various tidal volumes and peak pressures, and we determined in each compartment the expiratory time at which the pressure declined to 50% (t(50)) of the end-inspiratory pressure, and the maximal differences of t(50) (Delta t(50)) and pressure (Delta p(max)) between all compartments. Main results: During FLEX and FCV, t(50) was 6- to 7-fold higher compared to VCV and PCV (all P < 0.001). During VCV and PCV, Delta t(50) was higher (128 +/- 18 ms) compared to FLEX and FCV (49 +/- 19 ms; all P < 0.001). Delta p(max) reached up to 3.8 +/- 0.2 cmH(2)O during VCV and PCV, but only 0.6 +/- 0.1 cmH(2)O during FLEX and FCV (P < 0.001). Significance: FLEX and FCV provide a more homogeneous expiratory pressure distribution between compartments with different mechanical properties compared with VCV and PCV. This may reduce shear stress within inhomogeneous lung tissue.