[The evaluation of the oxygen-conserving valve during exertion]

The oxygen-conserving valve (OCV) permits reduction in oxygen consumption upon the release of oxygen only during inhalation thereby increasing the autonomy of portable sources.

In order to confirm its efficacy during exercise, 15 patients with chronic limitation of air flow and gasometric criteria of domiciliary oxygen therapy were selected. The patients underwent three walking tests (WT) of 6 minutes during which the continuous form of transcutaneous hemoglobin saturation (SaO2) and the distance covered were registered. The first was carried out breathing synthetic air at a flow of 2 liters per minute; the second with continuous oxygen released by a portable source at 2 liters per minute and the third with the OCV coupled to a portable source at the same flow.

SaO2 reached with the continuous oxygen is significantly higher to that of synthetic air while there was no difference between the SaO2 with continuous oxygen and with valve. Improvement in SaO2 upon use the valve was not obtained in only 2 of the 15 patients. A significant increase was observed in the distance covered upon oxygen administration not only in the continuous form but also with OCV with respect to synthetic air.

OCV is as effective as continuous oxygen in the correction of desaturation during exercise, however its indications must be individualized by exercise tests (WT) in each patients in order to ensure its correct functioning.