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. Each subject performed one 6-min walk test with each oxygen system, and we measured blood oxygen saturation (via pulse oximetry [S(pO(2))]), heart rate, and modified Borg dyspnea score, and surveyed the subjects' preferences about the oxygen systems. We also studied whether the 2 systems that provide gas with a lower oxygen concentration (from a home concentrator or portable concentrator) showed any evidence of not providing adequate oxygenation. RESULTS With all 4 systems the mean pre-walk S(pO(2)) at the prescribed pulse-dose setting was 95-96%. The mean post-walk S(pO(2)) was 88-90% after each of the 4 walk tests. Between the 4 systems there were no statistically significant differences between the pre-walk-versus-post-walk S(pO(2)) ( = .42). With each system, the pre-walk-versus-post-walk S(pO(2)) difference was between -8% and -6%. CONCLUSIONS Between these 4 ambulatory oxygen systems there were no significant differences in S(pO(2)), walk time, or walk distance, and there was no evidence of inadequate oxygenation with the 2 systems that provide a lower oxygen concentration.