Correlation and compatibility between surface respiratory electromyography and transesophageal diaphragmatic electromyography measurements during treadmill exercise in stable patients with COPD

Abstract

Purpose

To evaluate the compatibility and correlation between noninvasive surface respiratory electromyography and invasive transesophageal diaphragmatic electromyography measurements as facilitating indicators of neural respiratory drive (NRD) evaluation during treadmill exercise.

Patients and methods

Transesophageal diaphragmatic electromyogram activity (EMGdi,es) and surface inspiratory electromyogram (EMG) activity, including surface diaphragmatic EMG activity (EMGdi,sur), surface parasternal intercostal muscle EMG activity (EMGpara), and surface sternocleidomastoid EMG activity (EMGsc), were detected simultaneously during increasing exercise capacity in 20 stable patients with COPD. EMGdi,es, EMGdi,sur, EMGpara, and EMGsc were quantified using the root mean square (RMS) and were represented as RMSdi,es, RMSdi,sur, RMSpara, and RMSsc, respectively.

Results

There was a significant association between EMGdi,es and EMGdi,sur (r=0.966, p<0.01), EMGpara (r=0.967, p<0.01), and EMGsc (r=0.956, p<0.01) in the COPD patients during exercise. Bland-Altman plots showed that the lowest mean bias value was between EMGdi,es and EMGpara compared with the bias values between EMGdi,es and the other two EMG parameters. In comparing the estimation of EMGdi,es, we observed the lowest bias values (−1%) and the lowest limits of agreement values (−10% to −12%). Intraclass correlation coefficient (ICC) between EMGdi,es and EMGdi,sur was 0.978 (p<0.01), between EMGdi,es and EMGpara was 0.980 (p<0.01), and between EMGdi,es and EMGsc was 0.868 (p<0.01).

Conclusion

RMSdi,sur, RMSpara, and RMSsc could provide useful physiological markers of NRD in COPD. RMSpara shows the best compatibility and correlation with transesophageal diaphragmatic electromyography during treadmill exercise in stable patients with COPD.

Keywords:

• neural respiratory drive
• transesophageal diaphragmatic EMG
• surface diaphragmatic EMG
• surface sternocleidomastoid EMG
• surface parasternal intercostal muscle EMG

Acknowledgments

The study was supported by the Science and Technology Project of Guangdong Province (2017A020211018), the Guangzhou Healthcare Collaborative Innovation Major Project (201604040012), and the State’s Key Project of Research and Development Plan (2017YFSF11078).

Author contributions

RCC conceived the study and determined the study program. WLW, LLG, and XYL drafted and submitted the manuscript. LL, YQY, and BPG acquired the training devices and detecting instruments. ZYL and FYW collected and analyzed data. WLW interpreted data. All authors contributed toward data analysis, drafting and critically revising the paper, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interests in this work.