[Oxygen therapy by a portable concentrator with a demand valve: a randomised controlled study of its effectiveness in patients with COPD].
INTRODUCTION
There is doubt concerning the clinical effectiveness of portable oxygen concentrators with a control valve (PCDV) and their appreciation by patients. Objectives. To compare the effectiveness and appreciation of oxygen therapy by PCDV and liquid oxygen by continuous f low (O(2)Liq).


METHODS
Nineteen patients with COPD were randomised to receive PCDV or O(2)Liq at rest and during a 6 minute walk test (6MWT). For each mechanism they assessed, by visual analogue scales, the convenience and portability, the noise, and the discomfort of the nasal oxygen delivery.


RESULTS
The 6MW distance was 315 ± 120 m with PCDV and 325 ± 114 m with O(2)Liq (P>0.05). Dyspnoea and the desaturation induced by the 6MWT were identical with both systems (P>0.05). The time spent with a SaO(2)<90 % was 289 ± 69 s with PCDV and 242 ± 130 s with O(2)Liq (P=0.08). PCDV was noisier than O(2)Liq (P<0.05); there was no difference in convenience and portability or in nasal discomfort.


CONCLUSION
The PCDV model that we tested was equally effective to O(2)Liq. However, the prescription of this type of system is a matter of personal choice.