Rafols-de-Urquia Magda, Estevez-Piorno Josep, Estrada Luis, Garcia-Casado Javier, Prats-Boluda Gema, Sarlabous Leonardo, Jane Raimon, Torres Abel
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:3350-3353. doi: 10.1109/EMBC.2018.8512953.
The assessment of respiratory muscle activity by surface electromyography (sEMG) is a promising noninvasive technique for the diagnosis and monitoring of chronic obstructive pulmonary disease. The diaphragm is the most important muscle in breathing, although in forced inspiration other muscles, such as sternocleidomastoid, are activated and contribute to the respiratory process. The measurement of the sEMG in these muscles (sEMGdi and sEMGscm, respectively) by means of two electrodes in conventional bipolar configuration (BEs) is a common practice to evaluate the respiratory muscle activity and allows to indirectly quantify the level of muscular activation. However, the resulting signals are usually contaminated by electrocardiographic (ECG) activity, hindering the assessment of the activity of these muscles. sEMG signals can also be recorded using concentric ring electrodes (CREs). CREs have greater spatial resolution and attenuate distant bioelectrical interferences. In this scenario, the objective of this work has been to evaluate the applicability of CREs for the acquisition of sEMGdi and sEMGscm. For this purpose, both sEMG signals were recorded simultaneously with BEs and CREs in healthy subjects while performing an inspiratory load protocol. To evaluate the effect of the cardiac interference, the ratio between the mean power in inspiratory segments without ECG and the mean power in expiratory segments with ECG (Rcardio) was calculated. Additionally, the ratio between the mean power in inspiratory segments without ECG and the mean power in expiratory segments without ECG (Rinex) was also calculated. The results revealed that the Rcardio and bandwidth is greater in sEMG signals acquired with the CREs, while the Rinex is higher in the signals acquired with BEs. These results suggest that the use of CREs is a recommended alternative for the acquisition of sEMG in muscles with high cardiac interference, such as the diaphragm muscle.
通过表面肌电图（sEMG）评估呼吸肌活动是一种很有前景的非侵入性技术，可用于慢性阻塞性肺疾病的诊断和监测。膈肌是呼吸过程中最重要的肌肉，不过在用力吸气时，其他肌肉如胸锁乳突肌也会被激活并参与呼吸过程。采用传统双极配置（BEs）的两个电极来测量这些肌肉的sEMG（分别为sEMGdi和sEMGscm）是评估呼吸肌活动的常用方法，并且能够间接量化肌肉激活水平。然而，所得到的信号通常会被心电图（ECG）活动干扰，从而妨碍对这些肌肉活动的评估。sEMG信号也可以使用同心环形电极（CREs）来记录。CREs具有更高的空间分辨率，能够衰减远处的生物电干扰。在这种情况下，本研究的目的是评估CREs用于采集sEMGdi和sEMGscm的适用性。为此，在健康受试者执行吸气负荷方案时，同时使用BEs和CREs记录这两种sEMG信号。为了评估心脏干扰的影响，计算了无ECG的吸气段平均功率与有ECG的呼气段平均功率之比（Rcardio）。此外，还计算了无ECG的吸气段平均功率与无ECG的呼气段平均功率之比（Rinex）。结果显示，使用CREs采集的sEMG信号中Rcardio和带宽更大，而使用BEs采集的信号中Rinex更高。这些结果表明，对于心脏干扰较高的肌肉如膈肌，使用CREs是采集sEMG的推荐替代方法。
