Noninvasive ventilation during walking in patients with severe COPD: a randomised cross-over trial

It was hypothesised that noninvasive positive-pressure ventilation (NPPV) applied during walking prevents exercise-induced hypoxaemia and improves exercise performance in severe chronic obstructive pulmonary disease (COPD) patients already receiving long-term NPPV. A total of 20 COPD patients (mean+/-sd age 65.1+/-8.7 yrs, forced expiratory volume in one second 27+/-8% predicted and total lung capacity 116+/-27% pred) reporting dyspnoea, even during mild exertion, underwent two 6-min walking tests with a rollator and supplemental oxygen (2.1+/-0.9 L.min(-1)) in a randomised cross-over design: with and without pressure-limited NPPV as used at home (inspiratory:expiratory pressure 2.9+/-0.44:0.4+/-0.1 kPa (29+/-4:4+/-1 mbar), respiratory frequency 20+/-2 breaths.min(-1)). The arterial oxygen tension significantly increased by 1.39+/-1.43 kPa (95% confidence interval (CI) 0.71-2.07 kPa) after walking with NPPV, but significantly decreased by 1.43+/-1.06 kPa (95% CI -1.92 - -0.94 kPa) without NPPV. Dyspnoea, as assessed by the Borg dyspnoea scale, significantly decreased from 6 (interquartile range (IQR) 4.5-10) to 4 (1.5-4.5) and walking distance significantly increased from 209 (IQR 178-279) to 252 (203-314) m when walking was NPPV-aided. In chronic hypercapnic chronic obstructive pulmonary disease, high-intensity noninvasive positive-pressure ventilation can also be administered during walking with unchanged ventilator settings compared with settings used at rest, thus resulting in improved oxygenation, decreased dyspnoea and increased walking distance. Therefore, noninvasive positive-pressure ventilation during walking could prevent hypoxia-induced complications and could, in future, play a role in palliative care.