Transdiaphragmatic pressure and neural respiratory drive measured during inspiratory muscle training in stable patients with chronic obstructive pulmonary disease

Abstract

Purpose

Inspiratory muscle training (IMT) is a rehabilitation therapy for stable patients with COPD. However, its therapeutic effect remains undefined due to the unclear nature of diaphragmatic mobilization during IMT. Diaphragmatic mobilization, represented by transdiaphragmatic pressure (Pdi), and neural respiratory drive, expressed as the corrected root mean square (RMS) of the diaphragmatic electromyogram (EMGdi), both provide vital information to select the proper IMT device and loads in COPD, therefore contributing to the curative effect of IMT. Pdi and RMS of EMGdi (RMSdi%) were measured and compared during inspiratory resistive training and threshold load training in stable patients with COPD.

Patients and methods

Pdi and neural respiratory drive were measured continuously during inspiratory resistive training and threshold load training in 12 stable patients with COPD (forced expiratory volume in 1 s ± SD was 26.1%±10.2% predicted).

Results

Pdi was significantly higher during high-intensity threshold load training (91.46±17.24 cmH₂O) than during inspiratory resistive training (27.24±6.13 cmH₂O) in stable patients with COPD, with P<0.01 for each. Significant difference was also found in RMSdi% between high-intensity threshold load training and inspiratory resistive training (69.98%±16.78% vs 17.26%±14.65%, P<0.01).

Conclusion

We concluded that threshold load training shows greater mobilization of Pdi and neural respiratory drive than inspiratory resistive training in stable patients with COPD.

Keywords:

• diaphragmatic electromyogram
• inspiratory threshold load training
• inspiratory resistive training
• pulmonary rehabilitation
• respiratory physiological detection

Acknowledgments

We thank Xiao-cong Li for contributing to the recruitment of healthy controls and COPD patients in this study. We also thank Wallace Lee, Director of Celki VitalAire Company, for assisting us in purchase of inspiratory training devices – inspiratory resistive trainers^® and inspiratory threshold trainers^®.

Author contributions

RC and LZ contributed to study conception and design. WW and XZ drafted the submitted article and revised the draft critically for important intellectual content. RC and LZ contributed to revision of the draft critically for important intellectual content and provided final approval of the version to be published. LL, YO, and XL contributed to acquisition, analysis, and interpretation of data, in addition to drafting the submitted article. LG and BG contributed to acquisition of data, analysis and interpretation of data, as well as contributed to revising the draft critically for important intellectual content. All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.