Breathing gas analyzer

• US 3,996,010 A
• Filed: 03/25/1976
• Issued: 12/07/1976
• Est. Priority Date: 11/29/1974
• Status: Expired due to Term

• Current Assignee: Biochem International, Inc.
• Original Assignee: Searle Cardio-Pulmonary Systems Incorporated
• Inventors: Fraser, Robert B.
• Primary Examiner(s): Reese, Robert M.
• Application Number:
  US05/670,127
• Time in Patent Office: 257 Days
• Field of Search: 23/254 E, 23/254 R, 23/255 E, 23/255 R, 23/232 E, 23/232 R, 356/187, 356/178, 250/226, 250/564, 250/573, 250/575, 250/576, 313/217, 313/218
• US Class Current: 422/84
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: G01N 21/69 specially adapted for fluids , e.g. molten metal

Abstract

A breathing gas analyzer, especially for pulmonary use, has a frame supporting a centrally mounted radiation or analyzing chamber of about 1 and one-half to 25 millimeters (0.06 to 1.0 inches) substantially uniform inside diameter, having a circular-cylindrical transparent wall with closed ends connected in an electrical circuit and providing an anode of brass or stainless steel and a cathode of tantalum and constituting a discharge tube. Leading from a patient'"'"'s breathing tube is a conduit passing axially through the cathode, the conduit having an inside diameter of about 0.03 to 0.25 inches (0.7 to 6.4 millimeters). The chamber is subjected to subatmospheric pressure of about 0.2 to 10.0 torr through a duct from about one thirty-second to one-quarter inches (0.8 to 6.4 millimeters) inside diameter, passing through the anode to a vacuum pump. Arrayed equidistantly from the axis and around the chamber are one or more radiation detection devices positioned opposite the negative glow region of the discharge. The detection devices may be connected to a display device. There are individual apertures and filters interposed between the chamber and each of the detecting devices.

Claims

1. A breathing gas analyzer especially for pulmonary use comprising a cylindrical analyzing chamber of transparent insulating material and of substantially uniform internal diameter of from about 0.06 to 1.0 inches between said ends, a cathode at one end of said chamber and having extending axially therethrough a conduit of a diameter of about 0.03 to 0.25 inches adapted to be connected to a source of breathing gas, an anode at the other end of said chamber and having extending axially therethrough a duct of a diameter of about 0.03 to 0.25 inches for connecting said chamber to a sub-atmospheric pressure and thereby draw gases from said conduit through said chamber and out said duct, means for applying to said cathode and said anode a voltage difference to cause radiation from gas in said chamber and establish a negative glow region in said chamber, a radiation detection device disposed alongside said chamber in a direct radiation path therefrom, means disposed in said path for limiting radiation on said device to radiation from said negative glow region, and a radiation filter in said path adapted to transmit primarily radiation from a selected gas in said negative glow region.

2. An analyzer as in claim 1 in which said radiation limiting means is an apertured disc.

3. An analyzer as in claim 1 in which said radiation limiting means is a lens.

4. An analyzer as in claim 1 in which the operating pressure in said analyzing chamber ranges from about 0.2 torr to 10.0 torr.

5. An analyzer as in claim 1 in which the gas flow rate through said analyzing chamber is about 2.0 to 50.0 cc/minute.

6. An analyzer as in claim 1 in which the current for a one-quarter inch diameter analyzing chamber is about 0.3 to 1.5 milliamperes.

7. An analyzer as in claim 1 in which said means for limiting radiation from said negative glow region passes radiation only from a zone that extends from the end surface of said cathode to the end of said negative glow toward said anode.