Open circuit system for respiration testing

Claim 1

An open-circuit device for respiration testing comprising in combination: a. a first enclosure of fixed dimension, b. a spirometer connected to said enclosure so as to be actuated by changes in gas volume occurring within the confines of said first enclosure, c. a second enclosure having expansible/contractible wall area, said second enclosure being located within said first enclosure, d. a mouthpiece adapted to be worn by the subject to be tested, a first conduit connected between said mouthpiece and said first enclosure and a second conduit connected between said mouthpiece and said second enclosure, first valve means connected in one of said first and second conduits to provide flow only to said mouthpiece and second valve means connected in the other of said first and second conduits to provide flow only away from said mouthpiece, e. first means for controllably displacing a gaseous volume, said volume displacing means being connected to said first enclosure, f. a second means for controllably displacing a gaseous volume, said volume displacing means being connected to said second enclosure, said first and second volume displacement means being synchronized to simultaneously remove gas from one of said enclosures and introduce gas into the other of said enclosure with the volumetric rates of removal and introduction being substantially equal, said first and second conduits being connected to direct exhaled breath to said one of said enclosures and enable inhalation from said other of said enclosures and g. means responsive to the expansion and contraction of said second enclosure for controlling simultaneous intermittent operation of said first and second volume displacement means.