Randomised trial of ambulatory oxygen in oxygen-dependent COPD

We would like to thank T.L. Petty for his interesting comments regarding our trial of ambulatory oxygen (AO) in chronic obstructive pulmonary disease (COPD) [1]. The question raised by T.L. Petty was the following: when is the best time to initiate AO in oxygen-dependent COPD? He suggested AO should be provided as early as possible after the introduction of long-term oxygen therapy (LTOT) to avoid rapid adjustment to the limitations imposed by the stationary oxygen delivery system.