A randomized multi-arm repeated-measures prospective study of several modalities of portable oxygen delivery during assessment of functional exercise capacity.

Background: Ambulatory oxygen is an important component of long-term oxygen therapy. Pulse-dose technology conserves oxygen and thus increases the operation time of a portable oxygen system.

Methods: We tested 4 ambulatory oxygen systems (Helios, HomeFill, FreeStyle, and the compressed-oxygen cylinder system we regularly provide for long-term oxygen therapy at our Veterans Affairs hospital) with 39 subjects with stage-IV chronic obstructive pulmonary disease.