Measuring device for metabolic quantities connectable to a respirator

• US 4,856,531 A
• Filed: 08/17/1987
• Issued: 08/15/1989
• Est. Priority Date: 11/21/1984
• Status: Expired due to Term

• Current Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Original Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Inventors: Merilainen, Pekka
• Primary Examiner(s): Coven, Edward M.
• Assistant Examiner(s): Citrin, Randy
• Application Number:
  US07/087,984
• Time in Patent Office: 729 Days
• Field of Search: 128/719, 128/730, 128/204.22
• US Class Current: 600/532
• CPC Class Codes: A61B 5/0813 Measurement of pulmonary parameters by tracers, e.g. radioactive tracers
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption

Abstract

The invention relates to a device intended for monitoring the carbon dioxide output, oxygen consumption and respiration quotient of a patient connected to a respirator. The device comprises O₂ (15) and CO₂ (14) analyzers, a mixing chamber (6), a constant flow fan (8), a gas collector hose (2) and magnetic valves (10-13). The carbon dioxide output and oxygen consumption are directly calculated from the carbon dioxide content of gas mixed with constant air flow from said mixing chamber, from the carbon dioxide and oxygen contents of the gas in said mixing chamber, and from the oxygen content of the gas delivered into a patient by said respirator.

Claims

1. An apparatus for monitoring the carbon dioxide output, oxygen consumption and respiration quotient of a patient, comprising a respirator having an inlet conduit for supplying gas to a patient and having an outlet conduit for discharging exhalation gas from said patient, a mixing chamber connected to said outlet conduit and having an outlet means to discharge said gas from said chamber, air supply means connected to said outlet means for mixing air at a constant flow rate with said gas to provide a diluted gas, means for measuring the carbon dioxide content of said diluted gas, means for measuring the carbon dioxide content of said exhalation gas in said mixing chamber, means for measuring the oxygen content of said exhalation gas in said mixing chamber, means for measuring the oxygen content of the gas delivered through said inlet conduit to the patient, and means for determining the carbon dioxide output and oxygen consumption by direct calculation from said measured contents.

2. The apparatus of claim 1, wherein said air supply means comprises a blower and said outlet means comprises a channel disposed downstream of said blower.

3. The apparatus of claim 2, wherein said mixing chamber includes a bottom portion, said outlet means is located at the bottom portion of the mixing chamber and said outlet means includes a T-fitting having a stem communicating with said mixing chamber and having a pair of aligned arms, one of said arms communicating with said blower and the other of said arms communicating with the atmosphere, said T-fitting being disposed below said mixing chamber whereby water condensing in said mixing chamber automatically drains by gravity through said fitting and said second arm.

4. A method of monitoring the carbon dioxide output, oxygen consumption and respiration quotient of a patient connected to a respirator, comprising the steps of delivering exhalation gas discharged from a respirator to a mixing chamber, flowing said exhalation gas out of said chamber and mixing said gas with air having a constant rate of flow to dilute said gas, measuring the carbon dioxide content of said diluted gas, measuring the carbon dioxide content of the exhalation gas in said chamber, measuring the oxygen content of said exhalation gas in said chamber, measuring the oxygen content of gas delivered by said respirator to said patient, and determining the carbon dioxide output and oxygen consumption by direct calculation from said measured contents.

5. The method of claim 4, wherein an air supply means is operated by supply said air, said air supply means being operated in a manner to draw gas from said mixing chamber and mix said gas with said air to provide a constant flow of said mixture.