Effectiveness of a new oxygen demand valve in chronic hypoxemia.

The purpose of this study was to compare the efficacy of nasal oxygen delivery by an inspiratory demand valve, which delivers oxygen only during the inspiratory phase, to standard continuous flow oxygen. The inspiratory demand valve attaches to an oxygen source and delivers oxygen after the sensor detects negative pressure through a standard nasal cannula. Seventeen male patients with chronic hypoxemia secondary to COPD were studied under resting conditions. Nine patients with hypoxemia at rest or with exercise were studied using an exercise protocol. Oxygen was delivered at a flow rate which improved the oxygen saturation by 4 percent. Oxygen saturation was measured continuously by an ear oximeter. The results indicate that oxygen saturation was not significantly different for either method of oxygen delivery at rest or during exercise. The time oxygen was delivered was significantly reduced during demand valve use, being 55 percent less at rest and 52 percent less during exercise when compared to continuous oxygen. Further study would be helpful to determine whether the device would reliably deliver oxygen during continuous use and whether it could be adapted to portable systems.