reservoir oxygen-conserving device

res·er·voir ox·y·gen-con·ser·ving de·vice

(rez'ĕr-vwahr ok'si-jĕn-kŏn-sĕr'ving dĕ-vīs')
A device that stores oxygen in valveless expandable chambers under the nostrils or through large-bore tubing in a single valveless chamber worn on the chest; during inhalation through the nostrils, the oxygen is evacuated from the reservoir; conservation of oxygen is achieved because the constant flow of oxygen from the source can be reduced.