Patent attributes
Spirometer apparatus comprising main inhale-exhale tube having first end, main interior, and second open end, a plurality of smaller tubes intersecting said main-inhale exhale tube at first and second respective locations and having a plurality of smaller interiors respectively, the first location being closer to the first end than is the second location, wherein each of the smaller interiors are in fluid communication with the main interior solely via at least one aperture formed in each of the intersecting tubes at locations facing said second end, the intersecting tubes having first and second external cross-sections, the main tube having first and second internal cross-sections, wherein said first external cross-section is smaller than said first internal cross-section, said second external cross-section is smaller than said second internal cross-section, and wherein said second external cross-section is smaller than said first external cross-section, and a differential pressure sensor sensing the pressure drop.
