Metabolic gas monitoring apparatus and method

Claim 1

An apparatus for measuring the metabolic rate of a patient, comprising: (a) a first inlet conduit for receiving expired gas from the respiratory system of a patient; (b) a second inlet conduit for receiving gas as inspired by the patient; (c) a third inlet conduit for receiving a calibration gas; (d) an outlet conduit; (e) regulating means, positioned between said inlet conduits and said outlet conduit, for alternately regulating a continuous flow through said outlet conduit of one of said expired gas from the first inlet conduit, inspired gas from the second inlet conduit, or calibration gas from the third inlet conduit, said regulating means thereby serving to alternately allow passage of one gas at a time through said outlet conduit; (f) a cooler for cooling gas passing therethrough, said cooler being in gaseous communication with said outlet conduit so as to be positioned on the output side of said regulating means and said cooler serving to remove water from or add water vapor to the gas continuously flowing from said regulating means as needed to approximately equalize the water vapor pressure of each gas flowing through said cooler; (g) first sensing means in communication with the cooler for measuring the amount of carbon dioxide in a gaseous sample; (h) second sensing means in communication with the cooler for measuring the amount of oxygen in a gaseous sample; and (i) means for comparing the amounts of carbon dioxide and oxygen in one gaseous sample with those in another gaseous sample.

Claim 2

An apparatus for measuring the metabolic rate of a patient, comprising: (a) a first inlet conduit for receiving expired gas from the respiratory system of a patient; (b) a second inlet conduit for receiving gas as inspired by the patient; (c) a third inlet conduit for receiving a calibration gas; (d) an outlet conduit; (e) regulating means, positioned between said inlet conduits and said outlet conduit, for alternately regulating a continuous flow through said outlet conduit of one of said expired gas from the first inlet conduit, inspired gas from the second inlet conduit, or calibration gas from the third inlet conduit, said regulating means thereby serving to alternately allow passage of one gas at a time through said outlet conduit; (f) a cooler for cooling gas passing therethrough, said cooler being in gaseous communication with said outlet conduit so as to be positioned on the output side of said regulating means and said cooler serving to remove water from or add water vapor to the gas continuously flowing from said regulating means as needed to approximately equalize the water vapor pressure of each gas flowing through said cooler; (g) first sensing means in communication with the cooler for measuring the amount of carbon dioxide in a gaseous sample; (h) second sensing means in communication with the cooler for measuring the amount of oxygen in a gaseous sample; and (i) means for comparing the amounts of carbon dioxide and oxygen in one gaseous sample with those in another gaseous sample.

Claim 13

An apparatus for measuring the concentration of oxygen and carbon dioxide in expired gas from a patient, comprising: (a) a first inlet conduit for receiving expired gas from the respiratory system of a patient; (b) a second inlet conduit for receiving calibration gas; (c) an outlet conduit; (d) regulating means, positioned between said inlet conduits and said outlet conduit, for alternately regulating a continuous flow through said outlet conduit of one of said expired gas from the first inlet conduit or calibration gas from the second inlet conduit, said regulating means thereby serving to alternately allow passage of one gas at a time through said outlet conduit; (e) a cooler for cooling gas passing therethrough, said cooler being in gaseous communication with said outlet conduit so as to be positioned on the output side of said regulating means and said cooler serving to remove water from or add water vapor to the gas continuously flowing from said regulating means as needed to approximately equalize the water vapor pressure of each gas flowing through said cooler; (f) first sensing means in communication with the cooler for measuring the amount of carbon dioxide in the expired gas; and (g) second sensing means in communication with the cooler for measuring the amount of oxygen in the expired gas.

Claim 14

An apparatus for measuring the concentration of oxygen and carbon dioxide in expired gas from a patient, comprising: (a) a first inlet conduit for receiving expired gas from the respiratory system of a patient; (b) a second inlet conduit for receiving calibration gas; (c) an outlet conduit; (d) regulating means, positioned between said inlet conduits and said outlet conduit, for alternately regulating a continuous flow through said outlet conduit of one of said expired gas from the first inlet conduit or calibration gas from the second inlet conduit, said regulating means thereby serving to alternately allow passage of one gas at a time through said outlet conduit; (e) a cooler for cooling gas passing therethrough, said cooler being in gaseous communication with said outlet conduit so as to be positioned on the output side of said regulating means and said cooler serving to remove water from or add water vapor to the gas continuously flowing from said regulating means as needed to approximately equalize the water vapor pressure of each gas flowing through said cooler; (f) first sensing means in communication with the cooler for measuring the amount of carbon dioxide in the expired gas; and (g) second sensing means in communication with the cooler for measuring the amount of oxygen in the expired gas.

Claim 16

A method for measuring the metabolic rate of a patient, the method comprising the steps of: (a) providing a first inlet conduit for receiving expired gas from the respiratory system of a patient, a second inlet conduit for receiving gas as inspired by the patient, and a third inlet conduit for receiving a calibration gas; (b) alternately introducing into a cooler a continuous flow from one of said inlet conduits such that said expired gas, said inspired gas, and said calibration gas are introduced one at a time into said cooler; (c) cooling the gas within the cooler, the cooler serving to remove water from or add water vapor to the gas in said cooler as said gas continuously flows through said cooler; (d) calibrating a carbon dioxide sensor using the calibration gas and inspired gas and sensing the amount of carbon dioxide in the expired gas and the inspired gas; (e) calibrating an oxygen sensor using the calibration gas and sensing the amount of oxygen in the expired gas and the inspired gas; said oxygen sensor having a sample chamber and a reference chamber and said oxygen sensor further comprising means for providing communication between the sample chamber and the reference chamber such that a change in the pressure within the sample chamber results in a corresponding change of pressure within the reference chamber so as to maintain the pressure within said chambers substantially equal at all times; and (f) calculating the metabolic rate of the patient by comparing the amounts of carbon dioxide and oxygen in the expired gas with the amounts of carbon dioxide and oxygen in the inspired gas.

Claim 17

A method for measuring the metabolic rate of a patient, the method comprising the steps of: (a) providing a first inlet conduit for receiving expired gas from the respiratory system of a patient, a second inlet conduit for receiving gas as inspired by the patient, and a third inlet conduit for receiving a calibration gas; (b) alternately introducing into a cooler a continuous flow from one of said inlet conduits such that said expired gas, said inspired gas, and said calibration gas are introduced one at a time into said cooler; (c) cooling the gas within the cooler, the cooler serving to remove water from or add water vapor to the gas in said cooler as said gas continuously flows through said cooler; (d) calibrating a carbon dioxide sensor using the calibration gas and inspired gas and sensing the amount of carbon dioxide in the expired gas and the inspired gas; (e) calibrating an oxygen sensor using the calibration gas and sensing the amount of oxygen in the expired gas and the inspired gas; said oxygen sensor having a sample chamber and a reference chamber and said oxygen sensor further comprising means for providing communication between the sample chamber and the reference chamber such that a change in the pressure within the sample chamber results in a corresponding change of pressure within the reference chamber so as to maintain the pressure within said chambers substantially equal at all times; and (f) calculating the metabolic rate of the patient by comparing the amounts of carbon dioxide and oxygen in the expired gas with the amounts of carbon dioxide and oxygen in the inspired gas.

Claim 25

An apparatus for measuring the metabolic rate of a patient, comprising: (a) a first inlet conduit for receiving expired gas from the respiratory system of a patient; (b) a second inlet conduit for receiving gas as inspired by the patient; (c) a third inlet conduit for receiving a calibration gas; (d) regulating means for alternately regulating a continuous flow of one of said expired gas from the first inlet conduit, inspired gas from the second inlet conduit, or calibration gas from the third inlet conduit; (e) a cooler for cooling gas passing therethrough; said cooler being in gaseous communication with said regulating means and said cooler serving to remove water from or add water vapor to the gas continuously flowing from said regulating means as needed to approximately equalize the water vapor pressure of each gas flowing through said cooler; (f) first sensing means in communication with the cooler for measuring the amount of carbon dioxide in a gaseous sample; (g) second sensing means in communication with the cooler for measuring the amount of oxygen in a gaseous sample, said second sensing means having a sample chamber and a reference chamber and said second sensing means further comprising means for providing communication between the sample chamber and the reference chamber such that a change in the pressure within the sample chamber results in a corresponding change of pressure within the reference chamber so as to maintain the pressure within said chambers substantially equal at all times; and (h) means for comparing the amounts of carbon dioxide and oxygen in one gaseous sample with those in another gaseous sample.

Claim 26

An apparatus for measuring the metabolic rate of a patient, comprising: (a) a first inlet conduit for receiving expired gas from the respiratory system of a patient; (b) a second inlet conduit for receiving gas as inspired by the patient; (c) a third inlet conduit for receiving a calibration gas; (d) regulating means for alternately regulating a continuous flow of one of said expired gas from the first inlet conduit, inspired gas from the second inlet conduit, or calibration gas from the third inlet conduit; (e) a cooler for cooling gas passing therethrough; said cooler being in gaseous communication with said regulating means and said cooler serving to remove water from or add water vapor to the gas continuously flowing from said regulating means as needed to approximately equalize the water vapor pressure of each gas flowing through said cooler; (f) first sensing means in communication with the cooler for measuring the amount of carbon dioxide in a gaseous sample; (g) second sensing means in communication with the cooler for measuring the amount of oxygen in a gaseous sample, said second sensing means having a sample chamber and a reference chamber and said second sensing means further comprising means for providing communication between the sample chamber and the reference chamber such that a change in the pressure within the sample chamber results in a corresponding change of pressure within the reference chamber so as to maintain the pressure within said chambers substantially equal at all times; and (h) means for comparing the amounts of carbon dioxide and oxygen in one gaseous sample with those in another gaseous sample.