Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.
Electrical Engineering Department, Universidad de Concepcion, Concepción, Chile.
Artif Organs. 2022 Oct;46(10):1988-1997. doi: 10.1111/aor.14244. Epub 2022 Apr 12.
Diaphragm muscle atrophy during mechanical ventilation begins within 24 h and progresses rapidly with significant clinical consequences. Electrical stimulation of the phrenic nerves using invasive electrodes has shown promise in maintaining diaphragm condition by inducing intermittent diaphragm muscle contraction. However, the widespread application of these methods may be limited by their risks as well as the technical and environmental requirements of placement and care. Non-invasive stimulation would offer a valuable alternative method to maintain diaphragm health while overcoming these limitations.
We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. Respiratory pressure and flow, diaphragm electromyography and mechanomyography, and ultrasound visualization were used to assess the diaphragmatic response to stimulation. The electrode positions and stimulation parameters were systematically varied in order to investigate the influence of these parameters on the ability to induce diaphragm contraction with non-invasive stimulation.
We demonstrate that non-invasive capture of the phrenic nerve is feasible using surface electrodes without the application of pressure, and characterize the stimulation parameters required to achieve therapeutic diaphragm contractions in healthy volunteers. We show that an optimal electrode position for phrenic nerve capture can be identified and that this position does not vary as head orientation is changed. The stimulation parameters required to produce a diaphragm response at this site are characterized and we show that burst stimulation above the activation threshold reliably produces diaphragm contractions sufficient to drive an inspired volume of over 600 ml, indicating the ability to produce significant diaphragmatic work using non-invasive stimulation.
This opens the possibility of non-invasive systems, requiring minimal specialist skills to set up, for maintaining diaphragm function in the intensive care setting.
机械通气期间膈肌萎缩在 24 小时内开始，并迅速进展，具有显著的临床后果。使用侵入性电极对膈神经进行电刺激已显示出通过诱导间歇性膈肌收缩来维持膈肌状态的潜力。然而，这些方法的广泛应用可能会受到其风险以及放置和护理的技术和环境要求的限制。非侵入性刺激将提供一种有价值的替代方法来维持膈肌健康，同时克服这些限制。
我们在健康志愿者的颈部应用非侵入性膈神经电刺激。呼吸压力和流量、膈肌肌电图和肌动描记术以及超声可视化用于评估刺激对膈肌的反应。系统地改变电极位置和刺激参数，以研究这些参数对用非侵入性刺激诱导膈肌收缩的能力的影响。
我们证明使用表面电极无需施加压力即可实现膈神经的非侵入性捕获，并确定了在健康志愿者中实现治疗性膈肌收缩所需的刺激参数。我们表明，可以确定用于捕获膈神经的最佳电极位置，并且该位置不会随着头部方向的变化而改变。在此部位产生膈肌反应所需的刺激参数被表征，我们表明，高于激活阈值的爆发刺激可靠地产生足以驱动超过 600ml 吸气量的膈肌收缩，表明使用非侵入性刺激可以产生显著的膈肌做功。
这为在重症监护环境中维持膈肌功能的非侵入性系统开辟了可能性，这些系统需要最少的专业技能来设置。
