Inspiratory Muscle Training Potentiates the Beneficial Effects of Proportional Assisted Ventilation on Exertional Dyspnea and Exercise Tolerance in COPD: A Proof-of-Concept Randomized and Controlled Trial

Abstract

During pulmonary rehabilitation, a subset of subjects with COPD requires adjunct therapy to achieve high-intensity training. Both noninvasive ventilation (NIV) and inspiratory muscle training (IMT) are available to assist these subjects. We aimed to prime the respiratory muscles before NIV with IMT, anticipating additive effects for maximal exercise tolerance (T_lim) and dyspnea/leg fatigue relief throughout the exercise as primary outcomes. Changes in the respiratory pattern were secondary outcomes. COPD subjects performed a total of four identical constant work rate tests on a cycle ergometer at 75% of maximum work rate, under control ventilation (SHAM, 4 cm H₂O) or proportional assisted ventilation (PAV, individually adjusted), before and after 10 sessions of high-intensity IMT (three times/week) during 30 days. Two-way RM ANOVA with appropriate corrections were performed. Final analysis in nine subjects showed improved T_lim (Δ = 111 s) and lower minute-ventilation (Δ = 4 L^.min⁻¹) at exhaustion, when comparing the IMT effects within the PAV modality (p = 0.001 and p = 0.036, respectively) and improved T_lim for PAV vs. SHAM (PAV main-effect, p = 0.001; IMT main-effect, p = 0.006; PAV vs. IMT interaction, p = 0.034). In addition, IMT + PAV association, compared to PAV alone, resulted in lower respiratory frequency (IMT main-effect, p = 0.009; time main-effect, p < 0.0001; IMT vs. time interaction, p = 0.242) and lower inspiratory time related to duty cycle (IMT main-effect, p = 0.018; time main-effect, p = 0.0001; IMT vs. time interaction, p = 0.004) throughout exercise. The addition of IMT prior to a PAV-supported aerobic bout potentiates exercise tolerance and dyspnea relief and induces favourable changes in ventilatory pattern in severe COPD during high-intensity training (Brazilian Registry of Clinical Trials, number RBR-6n3dzz).

Keywords:

• COPD
• noninvasive ventilation
• inspiratory muscle training
• cardiopulmonary exercising test
• endurance
• dyspnea

Acknowledgments

The authors would like to thank Phillips Respironics, Inc. for supporting this work by providing the noninvasive V60 apparatus.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Data availability statement

The data are available upon request.

Specific author contributions

Rodrigo Koch: Data Collection, manuscript preparation, analysis of data and review; Tiago Augusto: Literature search, manuscript preparation, and review; Alessandro Ramos: Literature search, data collection, manuscript preparation, and review; Paulo Müller: Study design, literature search, data collection, analysis of data, manuscript preparation, and review.

Ethics

The author and coauthors have contributed substantially to this original work and approved the final submission. This work is not being considered for publication, in whole or in part, in another journal, book or conference proceedings and the author and coauthors have no conflicts of interest. The author and coauthors reviewed the final stages of the manuscript.