Apparatus for continuously measuring the CO.sub.2 content in breathing gases

• US 4,050,823 A
• Filed: 07/22/1976
• Issued: 09/27/1977
• Est. Priority Date: 09/05/1974
• Status: Expired due to Term

• Current Assignee: Dragerwerk AG
• Original Assignee: Dragerwerk AG
• Inventors: Frankenberger, Horst
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US05/707,503
• Time in Patent Office: 432 Days
• Field of Search: 356/51, 356/201, 356/205, 356/246, 356/184, 356/181, 356/186, 250/343, 250/573, 250/574, 250/576, 350/61, 128/2 C, 128/2 L, 128/2 R, 128/2.07
• US Class Current: 356/416
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis

Abstract

A method of continuously measuring the CO₂ content in breathing gases during inspiration and exhalation phases of breathing using a luminous source to pass infrared light rays through an interference filter accorded to CO₂ and a conduit of the gas to a photodetector, comprises passing the breathing gas developed during the breathing phases through the conduit to influence the photodetector to transmit a measured value signal in accordance with the CO₂ content, directing the signal to a breathing air phase recognition unit, storing the maxima and the minima of the measured value signals in each breathing phase in a maximum storage and a minimum storage, dividing the stored values under the control of the recognition unit and directing the values to a computation unit to indicate the logarithm of the values so as to give an indication of the variations of the CO₂ content. The indicated value is then directed to an indicating unit to show the value of the CO₂. The apparatus includes a tubular cell or conduit comprising a measuring cell which is arranged centrally between a luminous source and an interference filter accorded to CO₂ on one side and a photodetector on the other side thereof. A measuring cell tube is mounted on a stable support which is adapted to be warmed up during operation. The system includes a light modulator between the luminous source and the interference filter and a lens system for directing the light through the measuring cell and through the photodetector.

Claims

1. A gas measuring device comprising an annular mounting device having an opening therethrough, a respiratory gas tube extending through the opening and being held in said mounting device, a luminous source in said mounting device arranged on one side of said tube, an interference filter mounted on said mounting device and arranged in the path of rays from said luminous source and in the path of said tube, lens means on said mounting device for directing the rays through the tube and the gases therein, and a photodetector mounted on said mounting device on the other side of said tube from said luminous source.

2. A gas measuring device, according to claim 1, including a heater associated with said mounting means for heating said tube to prevent condensation.

3. A gas measuring device, according to claim 1, including a light modulator provided between said luminous source and said interference filter.