AIM: Evaluate the acute effects of non-invasive positive pressure ventilation (NiPPV) during high-intensity exercise on endothelial function in patients with coexisting chronic obstructive pulmonary disease (COPD) and heart failure (HF). METHODS: This is a randomized, double blinded, sham-controlled study involving 14 COPD-HF patients, who underwent a lung function test and doppler echocardiography. On two different days, patients performed incremental cardiopulmonary exercise testing (CPET) and two constant-work rate tests (80% of CPET peak) receiving sham or NiPPV (bilevel mode -- Astral 150) in a random order until the limit of tolerance (Tlim). Endothelial function was evaluated by flow mediated vasodilation (FMD) at three time points: (1) baseline; (2) immediately post-exercise with NiPPV; and (3) immediately post-exercise with sham. RESULTS: Our patients had a mean age of 70 +/- 7 years, FEV1 1.9 +/- 0.7 L and LVEF 41 +/- 9%. NIPPV resulted in an increased Tlim (NiPPV 130 +/- 29s versus sham 98 +/- 29s p = 0.015) and SpO2 (NiPPV 94.7 +/- 3.5% versus sham 92.7 +/- 5.2% p = 0.03). Also, NiPPV was able to produce a significant increase in FMD (%) (NiPPV 9.2 +/- 3.1 versus sham 3.6 +/- 0.7, p < 0.05), FMD (mm) (NiPPV 0.41 +/- 0.18 versus sham 0.20 +/- 0.11, p < 0.05), blood flow velocity (NiPPV 33 +/- 18 versus baseline 20 +/- 14, p < 0.05) and Shear Stress (SS) (NiPPV 72 +/- 38 versus baseline 43 +/- 25, p < 0.05). We found correlation between Tlim versus delta SS (p = 0.03; r = 0.57). Univariate-regression analysis revealed that increased SS influenced 32% of Tlim during exercise with NiPPV. CONCLUSION: NiPPV applied during high-intensity exercise can acutely modulate endothelial function and improve exercise tolerance in COPD-HF patients. In addition, the increase of SS positively influences exercise tolerance.

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