Abstract
Introduction: Nasal high flow therapy (NHFT) is an emerging treatment for a range respiratory conditions. Possible benefits include dead space washout, attenuation of inspiratory resistance, improved conductance/compliance, and gas conditioning. Given that exercise capacity in COPD is limited by a reduced ventilatory reserve it is possible that NHFT during exercise may facilitate ventilation resulting in less physiological strain and/or improved performance.
Aim: The purpose of this study was to evaluate the effect of NHFT on exercise performance in patients with COPD. The primary hypothesis: NHFT will improve exercise performance.
Methods: 21 subjects with moderate-very severe COPD performed two randomised six minute walk tests (6MWT) 30 minutes apart. One 6MWT was performed using NHFT (45 L.min-1, 37 deg. C, room air), the other one without (W). Subjects walked with the NHFT equipment and walking frame for both tests. Pulse oximetry, dyspnoea, respiratory rate and fatigue scores were recorded.
Results: There was no difference in the 6MWT distance (NHFT 351 ± 107m, W 349 ± 116m). There was no difference in the mean SpO2 (NHFT 91 ± 4%, W 91 ± 4%) and the nadir SpO2 (NHFT 88 ± 5%, W 87 ± 5%) between tests. There was no difference in the maximum pulse rate between tests. Nor were there any difference in dyspnoea and fatigue scores between tests. Maximum respiratory rate was 43 b.min-1 in both tests.
Conclusion: It is possible there were no measurable performance changes during NHFT as subjects were at their ventilatory ceiling in both tests. In this cohort of COPD patients, NHFT had no effect on exercise performance, physiological stress and perceived dyspnoea/fatigue.