Non-invasive ventilation during arm exercise and ground walking in patients with chronic hypercapnic respiratory failure

Background and objective:   People with chronic hypercapnic respiratory failure (HRF) often have a ventilatory limitation to exercise with difficulty performing activities of daily living. Although non-invasive ventilation (NIV) appears to reduce the ventilatory limitation and improve exercise performance in people with severe COPD, the effect of NIV during functional activities such as unsupported arm exercise (UAE) and ground walking in people with chronic HRF is unclear.
Methods:   Seventeen patients with chronic HRF (PaCO₂ 52.1 ± 5.3 mm Hg) performed a series of UAE tests, and 15 patients (PaCO₂ 51.7 ± 3.8 mm Hg) performed a series of endurance shuttle walk tests, with and without NIV in a randomized cross-over design.
Results:   NIV during UAE increased endurance time by a mean of 91 s (95% confidence interval (CI): 10–172, P  = 0.031) and reduced dyspnoea by a mean of 2.3 on the Borg scale (95% CI: 1.0–3.7, P  = 0.002) compared with exercise without NIV. There was a non-significant increase in walking endurance time with NIV during exercise (119 s, 95% CI: −17 to 254, P  = 0.081); however, isotime dyspnoea was unchanged compared with walking without NIV (−1.0, 95% CI: −3.0 to 1.0, P  = 0.29).
Conclusion:   NIV during UAE increased endurance time and reduced dyspnoea compared with exercise without NIV in patients with chronic HRF. Investigation of the role of NIV as an adjunct to UAE training is warranted. In contrast, NIV during ground walking did not improve exercise capacity. However, the pressure support provided may have been inadequate as dyspnoea was not reduced.