Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada.
Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.
Crit Care. 2024 Sep 18;28(1):310. doi: 10.1186/s13054-024-05091-y.
During mechanical ventilation, post-insufflation diaphragm contractions (PIDCs) are non-physiologic and could be injurious. PIDCs could be frequent during reverse-triggering, where diaphragm contractions follow the ventilator rhythm. Whether PIDCs happens with different modes of assisted ventilation is unknown. In mechanically ventilated patients with hypoxemic respiratory failure, we aimed to examine whether PIDCs are associated with ventilator settings, patients' characteristics or both.
One-hour recordings of diaphragm electromyography (EAdi), airway pressure and flow were collected once per day for up to five days from intubation until full recovery of diaphragm activity or death. Each breath was classified as mandatory (without-reverse-triggering), reverse-triggering, or patient triggered. Reverse triggering was further subclassified according to EAdi timing relative to ventilator cycle or reverse triggering leading to breath-stacking. EAdi timing (onset, offset), peak and neural inspiratory time (Ti) were measured breath-by-breath and compared to the ventilator expiratory time. A multivariable logistic regression model was used to investigate factors independently associated with PIDCs, including EAdi timing, amplitude, Ti, ventilator settings and APACHE II.
Forty-seven patients (median[25%-75%IQR] age: 63[52-77] years, BMI: 24.9[22.9-33.7] kg/m, 49% male, APACHE II: 21[19-28]) contributed 2 ± 1 recordings each, totaling 183,962 breaths. PIDCs occurred in 74% of reverse-triggering, 27% of pressure support breaths, 21% of assist-control breaths, 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths. PIDCs were associated with higher EAdi peak (odds ratio [OR][95%CI] 1.01[1.01;1.01], longer Ti (OR 37.59[34.50;40.98]), shorter ventilator inspiratory time (OR 0.27[0.24;0.30]), high peak inspiratory flow (OR 0.22[0.20;0.26]), and small tidal volumes (OR 0.31[0.25;0.37]) (all P ≤ 0.008). NAVA was associated with absence of PIDCs (OR 0.03[0.02;0.03]; P < 0.001). Reverse triggering was characterized by lower EAdi peak than breaths triggered under pressure support and associated with small tidal volume and shorter set inspiratory time than breaths triggered under assist-control (all P < 0.05). Reverse triggering leading to breath stacking was characterized by higher peak EAdi and longer Ti and associated with small tidal volumes compared to all other reverse-triggering phenotypes (all P < 0.05).
In critically ill mechanically ventilated patients, PIDCs and reverse triggering phenotypes were associated with potentially modifiable factors, including ventilator settings. Proportional modes like NAVA represent a solution abolishing PIDCs.
在机械通气过程中，通气后膈肌收缩（PIDCs）是非生理的，可能会造成损伤。在反向触发时，膈肌收缩跟随呼吸机节律，PIDCs 可能会很频繁。辅助通气的不同模式下是否会发生 PIDCs 尚不清楚。在接受机械通气的低氧性呼吸衰竭患者中，我们旨在研究 PIDCs 是否与呼吸机设置、患者特征或两者均有关。
从气管插管到膈肌活动完全恢复或死亡，每天记录 1 小时的膈肌肌电图（EAdi）、气道压力和流量。每一次呼吸都被分类为强制（无反向触发）、反向触发或患者触发。根据 EAdi 与呼吸机周期的时间关系或反向触发导致呼吸堆积，进一步将反向触发分为亚类。EAdi 时间（起始、结束）、峰值和神经吸气时间（Ti）逐次呼吸进行测量，并与呼吸机呼气时间进行比较。使用多变量逻辑回归模型研究与 PIDCs 独立相关的因素，包括 EAdi 时间、幅度、Ti、呼吸机设置和急性生理学与慢性健康状况评分系统 II（APACHE II）。
47 名患者（中位[25%-75%IQR]年龄：63[52-77]岁，BMI：24.9[22.9-33.7]kg/m2，49%为男性，APACHE II：21[19-28]）每人贡献了 2±1 次记录，总共 183962 次呼吸。反向触发中有 74%发生了 PIDCs，压力支持呼吸中有 27%，辅助控制呼吸中有 21%，神经调节通气辅助（NAVA）呼吸中有 5%。PIDCs 与更高的 EAdi 峰值（比值比[OR][95%CI]1.01[1.01；1.01]）、更长的 Ti（OR 37.59[34.50；40.98]）、更短的呼吸机吸气时间（OR 0.27[0.24；0.30]）、更高的吸气峰流量（OR 0.22[0.20；0.26]）和更小的潮气量（OR 0.31[0.25；0.37]）相关（所有 P≤0.008）。NAVA 与 PIDCs 缺失相关（OR 0.03[0.02；0.03]；P<0.001）。反向触发的 EAdi 峰值低于压力支持触发的呼吸，与较小的潮气量和较短的设定吸气时间相关，而反向触发的呼吸与辅助控制触发的呼吸相比（所有 P<0.05）。与所有其他反向触发表型相比，导致呼吸堆积的反向触发的特点是更高的 EAdi 峰值和更长的 Ti，并且与较小的潮气量相关（所有 P<0.05）。
在接受机械通气的危重症患者中，PIDCs 和反向触发表型与潜在可调节因素有关，包括呼吸机设置。比例模式如 NAVA 代表了一种消除 PIDCs 的解决方案。
