Systems, devices, and/or methods for measuring metabolic energy expenditure
Inventors
PARKER, JR., B. Eugene • Ehlmann, Kevin M. • Gressick, William T.
Assignees
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Publication Number
US-11529073-B1
Publication Date
2022-12-20
Expiration Date
Abstract
Certain exemplary embodiments can provide a system, machine, device, manufacture, circuit, composition of matter, and/or user interface adapted for and/or resulting from, and/or a method and/or machine-readable medium comprising machine-implementable instructions for, activities that can comprise and/or relate to, facilitating determination of the oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure of a mammal.
Core Innovation
The invention relates to a portable flowmeter-free indirect calorimetry system configured to facilitate determination of oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure of a mammal. The system includes a mixing tank configured to contain a mixture comprising at least a portion of each of a group of samples of exhaled gases provided by the mammal during a predetermined time period, with the tank configured to promote homogeneous mixing of the samples.
A flow tube routes each sample toward the mixing tank, and a conduit conveys the exhaled gases from the flow tube toward the mixing tank while reducing a water vapor pressure of the exhaled gases within the conduit to approximately a water vapor pressure in air outside the flow tube. The system further includes an oxygen sensor configured to measure a volumetric oxygen fraction of the mixture and a self-calibrating carbon dioxide sensor configured to measure a volumetric carbon dioxide fraction of the mixture.
A wireless transceiver conveys sensor measurement data, and a processor determines oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure based on the volumetric oxygen fraction and the volumetric carbon dioxide fraction measured in the mixing tank. The determined quantities are stated to be independent of a time constant of the oxygen sensor and a time constant of the carbon dioxide sensor.
Claims Coverage
The partial claim set includes two independent claims: an independent system claim and an independent method claim. Each independent claim is centered on determining oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure from volumetric oxygen and volumetric carbon dioxide fractions in a homogenized mixing tank, while reducing water vapor pressure in a conduit and specifying independence from sensor time constants for two sensors.
Homogeneous mixing in a mixing tank for exhaled gas samples
A mixing tank contains at least a portion of each of a group of samples of exhaled gases provided by the mammal during a predetermined time period, and the tank promotes homogeneous mixing of the samples.
Water vapor pressure reduction in the conduit to approximately ambient water vapor pressure
A conduit conveys the exhaled gases from the flow tube toward the mixing tank and reduces a water vapor pressure of the exhaled gases within the conduit to approximately a water vapor pressure in air outside the flow tube.
Oxygen and self-calibrating carbon dioxide volumetric fraction sensing in the mixing tank
An oxygen sensor measures a volumetric oxygen fraction of the mixture in the mixing tank, and a self-calibrating carbon dioxide sensor measures a volumetric carbon dioxide fraction of the mixture in the mixing tank.
Wireless transmission and processor-based determination from volumetric fractions
A wireless transceiver conveys sensor measurement data, and a processor determines oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure based on the volumetric oxygen fraction and the volumetric carbon dioxide fraction of the mixture in the mixing tank.
Determination independent of oxygen and carbon dioxide sensor time constants
The determined oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure is independent of a time constant of the oxygen sensor and a time constant of the carbon dioxide sensor.
Across the independent system claim and independent method claim, the inventive concept is the same: exhaled gas samples are conveyed through a conduit that reduces water vapor pressure to approximately ambient water vapor pressure, mixed in a mixing tank to form a homogeneous mixture, and analyzed by an oxygen sensor and a self-calibrating carbon dioxide sensor to obtain volumetric oxygen and carbon dioxide fractions. The processor determines oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure from those volumetric fractions, with the determination stated to be independent of sensor time constants for both sensors.
Stated Advantages
The determined oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure is independent of a time constant of the oxygen sensor and a time constant of the carbon dioxide sensor.
Documented Applications
Determination of oxygen consumption, carbon dioxide production, respiratory exchange ratio, and/or energy expenditure of a mammal using a flowmeter-free indirect calorimetry system.
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