Muscle Unloading During Exercise: Comparative Effects of Conventional Oxygen, NIV and High-Flow Therapy on Neural Drive in Severe COPD

Objectives: To evaluate how non-invasive ventilation (NIV) and high-flow nasal can-nula therapy (HFT) versus conventional oxygen therapy (COT) affect neural ventilatory drive during exercise in patients with severe chronic obstructive pulmonary disease (COPD). Methods Design: Experimental, controlled study with one arm and three dif-ferent conditions for the same cohort. After initial testing on conventional oxygen threapy (COT) patients performed in sequential days, in a random order, exercise under NIV and HFT. Participants: Twenty patients with severe COPD (30% women) on home NIV as a bridge to lung transplantation, with mean FEV₁ 19.78% predicted and marked hyperinflation. Protocol: Participants performed constant-load cycling exercises at 75% maximum tol-erated workload under three conditions: COT, NIV, and HFT. Neuro-respiratory drive (NRD) was measured using surface parasternal and sternocleidomastoid electromyog-raphy. Mixed ANOVA analyzed repeated measures across conditions. Results: 20 patients (age 60+- 3.9 years, 6 female) were included. NIV demonstrated superior performance with 60% lower NRD compared to COT (488.81 µV vs. 1180.63 µV, p< 0.05). HFT showed intermediate effects (807.8 µV). NIV also achieved greater reduc-tion in respiratory rate (4.2 breaths/min), lower perceived exertion (Borg score decrease: 1.8 points), and more pronounced CO₂ reduction (5.3 mmHg) compared to both COT and HFT. Conclusions: NIV significantly reduces NRD during exercise in severe COPD patients compared to HFT and COT. This supports its use as a valuable adjunct to pulmonary rehabilitation in severe COPD