Background

Recently, surface EMG of parasternal intercostal muscle has been incorporated in the "ERS Statement of Respiratory Muscle Testing" as a clinical technique to monitor the neural respiratory drive (NRD). However, the anatomy of the parasternal muscle risks confounding EMG "crosstalk" activity from neighboring muscles.

Objectives

To determine if surface “parasternal” EMG: 1) reliably estimates parasternal intercostal EMG activity, 2) is a valid surrogate expressing neural respiratory drive (NRD).

Methods

Fine wire electrodes were implanted into parasternal intercostal muscle in 20 severe COPD patients along with a pair of surface EMG electrodes at the same intercostal level. We recorded both direct fine wire parasternal EMG (EMGPARA) and surface estimated “parasternal” EMG (SurfEMGpara) simultaneously during resting breathing, volitional inspiratory maneuvers, apnoea with extraneous movement of upper extremity, and hypercapnic ventilation.

Results

Surface estimated “parasternal” EMG showed spurious "pseudobreathing" activity without any airflow while real parasternal EMG was silent, during apnoea with body extremity movement. Surface estimated “parasternal” EMG did not faithfully represent real measured parasternal EMG. Surface estimated “parasternal” EMG was significantly less active than directly measured parasternal EMG during all conditions including baseline, inspiratory capacity and hypercapnic ventilation. Bland-Altman analysis showed consistent bias between direct parasternal EMG recording and surface estimated EMG during stimulated breathing.

Conclusion

Surface “parasternal” EMG does not consistently or reliably express EMG activity of parasternal intercostal as recorded directly by implanted fine wires. A chest wall surface estimate of parasternal intercostal EMG may not faithfully express NRD and is of limited utility as a biomarker in clinical applications.

中文翻译：

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胸骨旁肋间表面肌电图估计推断神经呼吸驱动的局限性

背景

最近，胸骨旁肋间肌的表面 EMG 已被纳入“呼吸肌测试的 ERS ​​声明”，作为监测神经呼吸驱动 (NRD) 的临床技术。然而，胸骨旁肌肉的解剖结构可能会混淆来自邻近肌肉的 EMG“串扰”活动。

目标

确定表面“胸骨旁”肌电图：1) 可靠地估计胸骨旁肋间肌电图活动，2) 是表达神经呼吸驱动 (NRD) 的有效替代物。

方法

将细线电极植入20例重度COPD患者的胸骨旁肋间肌，并在同一肋间水平植入一对表面肌电图电极。我们在静息呼吸、自主吸气操作、呼吸暂停伴上肢外部运动和高碳酸血症通气期间同时记录直接细线胸骨旁肌电图 (EMGPARA) 和表面估计的“胸骨旁”肌电图 (SurfEMGpara)。

结果

表面估计的“胸骨旁”肌电图显示出没有任何气流的虚假“假呼吸”活动，而真正的胸骨旁肌电图在呼吸暂停和身体四肢运动期间是无声的。表面估计的“胸骨旁”肌电图并不能忠实地代表实际测量的胸骨旁肌电图。在包括基线、吸气量和高碳酸血症通气在内的所有条件下，表面估计的“胸骨旁”EMG 的活跃度明显低于直接测量的胸骨旁 EMG。Bland-Altman 分析表明，在刺激呼吸期间，胸骨旁直接 EMG 记录和表面估计 EMG 之间存在一致的偏差。

结论

表面“胸骨旁”EMG 不能一致或可靠地表达胸骨旁肋间的 EMG 活动，如由植入的细线直接记录的那样。胸骨旁肋间肌电图的胸壁表面估计可能不能忠实地表达 NRD，并且作为临床应用中的生物标志物的效用有限。