Patent GB-426140-A (GB)
Title: Improvements in a device for indicating oxygen consumption and formation of carbon dioxide in breathing
IPC: A61B5/095
Filed: 1933-09-30
Abstract: 426,140. Spirometers ; breath testing appliances. MANSFELD, G., 3, Vitez Utca, PÚcs, Hungary. Sept. 30, 1933, No. 26974. Convention date, Oct. 1, 1932. [Class 81 (ii)] Apparatus for the determination of the consumption of oxygen and production of carbon dioxide in breathing by a single breathing period in the same volume of air comprises a spirometer 1 divided into two chambers by a sack 4 of impermeable material such as rubber or rubberized fabric. The upper chamber is closed by a swinging cover 5 coacting with a water seal 6. The cover is loaded with an adjustable weight 7 and carries a recording arm 8 traversing drum 9. The mouthpiece 12 leads through a three-way cock 11 to the inhaling tube 10 which opens beneath the cover 5 and to the exhaling tube 13 which passes round the water seal and opens in the lower compartment of the spirometer. Tube 17 branches from the tube 13 via cock 16 and opens below an absorption vessel 20 in the upper part of the apparatus. This tube is also connected via air pump 22, absorption vessel 24 and tubes 25 and 26 with the lower compartment of the apparatus. In operation, the person breathes in from the air-filled spirometer, the exhaled air passing into the lower chamber of the spirometer. A curve registering the difference between oxygen consumption and carbon dioxide production is obtained on the drum 9, this curve gradually sinking owing to the oxygen consumption normally being greater than the production of carbon dioxides. When the breathing period is finished, the cock 11 is turned to close the spirometer from the outside air. The exhaled air is then withdrawn from the lower chamber by the fan 22 through the absorption vessels 20 and 24 and is passed into the upper chamber after being deprived of its carbon dioxide content. Finally the valves are turned so that the upper chamber communicates with the whole length of the various tubes and a circulation of air is promoted by the fan 22 so that the last traces of carbon dioxide are removed. Due to the absorption of carbon dioxide, the contents of the spirometer again decrease in volume and a second curve is recorded on the drum, the ordinates of which give the carbon dioxide absorbed. By addition of the ordinates of the two curves obtained, the oxygen consumption of the person or animal examined is determined. For a fresh determination, the used air is expelled through cock 31 and fresh air is drawn in and circulated through the absorption vessels to free it from carbon dioxide. A water channel 32 is provided in the lower part of the apparatus so that all the air is saturated with water vapour. Also all the tubes containing exhaled air pass through the water jacket to prevent any increase in volume due to temperature increases. The oxygen consumption may also be determined by enriching the air in the spirometer with oxygen from container 33 and passing the exhaled air back into the upper chamber after absorption of carbon dioxide. By a second breathing period in which the exhaled air is passed into the lower chamber as described above, a curve giving the difference between oxygen consumption and carbon dioxide production is obtained, from which two curves, the production of carbon dioxide may be determined. For the examination of small animals, they are placed in an air-tight container, placed in a water bath, and a pump draws the air from the upper chamber through the container and into the lower chamber.