Metabolic analyzer
First Claim
1. A metabolic analyzer comprising:
- CO2 detector means for determining a CO2 content of a respired gas;
O2 detector means for determining an O2 content of the respired gas;
flow detector means for providing a flow signal representative of the flow of the respired gas;
flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas;
pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means; and
processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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Accused Products
Abstract
A metabolic rate analyzer is provided comprising a CO2 detector, an O2 detector, a flow resistance, a differential pressure transducer, a solenoid-actuated metering valve for producing a volumetrically-proportional sample of respired gas, a vacuum regulator for receiving the sample, a pump for drawing the sample from the vacuum regulator, and a processor for periodically sampling the differential pressure signal to provide a flow signal, to modulate power applied to the solenoid-actuated flow proportioning valve, and to provide a measure of the total volume of respired gas. The processor correlates the total volume of respired gas, O2 content and CO2 content to provide a measure of metabolic rate. Flow is recycled between the pump and the regulator valve to provide a source of mixed respired gas for analysis and digital integration of the flow signal provides a measure of the total volume of respired gas. A pulse generator driven by the microprocessor varies the frequency of pulses applied to the metering valve and the pulse width to provide volumetrically-proportional sampling and to control the effective sample volume of the analyzer, respectively. The processor determines the slope of the flow signal and increases the periodic sample rate of the pressure signal when slope is increasing and decreases the periodic sample rate when slope is decreasing to provide derivative augmentation of the sample period.
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Citations
32 Claims
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1. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means, said pump means having a pump inlet and a pump outlet; vacuum regulator means for receiving the sample of the respired gas from said flow proportioning valve means and delivering the sample to said pump means, said vacuum regulator means having a regulator input port connected to said flow proportioning valve means for receiving the sample, a regulator output port maintained at a predetermined vacuum, and a regulator recycle port, said pump inlet being connected to said regulator output port and said pump outlet being connected to said regulator recycle port to provide a loop for mixing respired gas; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas, and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate. - View Dependent Claims (23, 24)
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25. A metabolic analyzer comprising:
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CO2 detector means for determining an CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and O2 detector means, said pump means having a pump inlet and a pump outlet; vacuum regulator means for receiving the sample of the respired gas from said flow proportioning valve means and delivering the sample to said pump means, said vacuum regulator means comprising; a regulator body defining a gas chamber; a regulator input port for receiving respired gas from said flow proportioning valve means; a regulator output port for delivering respired gas to said pump inlet; a flexible diaphragm disposed between said regulator input port and said regulator output port, said diaphragm dividing said gas chamber into an input side and an output side in fluid communication with said regulator input port and said regulator output port, respectively; a regulator metering port disposed in said diaphragm for establishing a fluid communication between said input side and said output side of said gas chamber; a regulator recycle port in fluid communication with said regulator output side; a regulator transfer port disposed in said output side of said gas chamber for supplying respired gas to said regulator output port, said diaphragm being spring-biased against said transfer port to keep said transfer port normally closed except for said metering port which extends therethrough; said pump inlet being connected to said regulator output port and said pump outlet being connected to said regulator recycle port to form a loop for mixing respired gas; and said pump outlet being connected to said CO2 detector means and said O2 detector means to provide a sample of mixed respired gas to said CO2 and O2 means when said flow proportioning valve means introduces a volume of respired gas to said input side of said gas chamber of said vacuum regulator means; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas, and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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26. A metabolic rate analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; a flow restriction through which the respired as is directed; differential pressure detector means connected to said flow restriction for providing a differential pressure signal representative off the flow of respired gas through said flow restriction; solenoid-actuated flow proportioning valve means adapted to be connected to a source of respired gas for delivering a small, representative and volumetrically-proportional sample of respired gas; vacuum regulator means for receiving the sample; pump means for drawing the sample from said vacuum regulator means and delivering the sample to said CO2 and O2 detector means; and processor means for converting said differential pressure signal into a flow signal that is representative of a volumetric flow of respired gas that established said differential pressure signal, said processor means using said flow signal to modulate electrical power applied to said solenoid-actuated flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas and correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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27. A metabolic rate analyzer comprising:
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CO2 detector means for providing a CO2 signal representative of the CO2 content of a respired gas; O2 detector means for providing an O2 signal representative of the O2 content of the respired gas; a sharp plate orifice through which the respired gas is directed; differential pressure transducer means for providing a pressure signal representative of the difference in pressure of the respired gas on opposite sides of said orifice; solenoid-actuated flow proportioning valve means adapted to be connected to a source of respired gas for delivering a small, representative volumetrically-proportional sample of respired gas; vacuum regulator means for receiving the sample of respired gas; pump means for drawing the sample of respired gas from said vacuum regulator means, said pump means being provided with a first output and a second output; said first output of said pump means being directed to said vacuum regulator means to provide a loop flow of mixed respired gas; said second output of said pump means being directed to said CO2 detector means and said O2 detector means for delivering mixed respired gas thereto; processor means for periodically sampling said pressure signal and taking the square root of said pressure signal to provide a flow signal representative of the flow of respired gas; pulse generator means having a variable frequency and variable pulse width output controlled by said processor means and said flow signal, the frequency of the output of said pulse generator means increasing with an increase in the flow signal and decreasing with a decrease in the flow signal, the output of said pulse generator means being applied to said solenoid-actuated flow proportioning valve means; said processor means summing said flow signals, dividing by the number of flow signals taken, and multiplying by elapsed time to provide a measure of the total volume of respired gas, thus effectively integrating said flow signal; said processor means monitoring said flow signal to determine a breath rate and for increasing the pulse width of the output of said pulse generator means when breath rate is low and for decreasing pulse width when breath rate is high, thus controlling an effective sample volume of the analyzer; said processor means having a variable period for sampling said flow signal, said processor means determining a slope of said flow signal for decreasing said period when the slope is increasing and increasing said period when the slope is decreasing, thus effecting derivative augmentation of said variable period for sampling; said processor means correlating said measure of the total volume of respired gas, said CO2 signal and said O2 signal to provide a measure of metabolic rate.
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28. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas, said CO2 detector means comprising a non-dispersive infrared (NDIR) gas analyzer having an infrared (IR) source and a means for calibrating said NDIR analyzer comprising a means for attenuating said IR source; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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29. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means, said pump means being provided with an inlet, a first output and a second output, said first output being connected back to said inlet to provide a recirculation loop of mixed respired gas and said second output being connected to said CO2 and O2 detector means to provide a sample of mixed respired gas; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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30. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said processor means having a sample period for sampling said flow signal, said processor means determining the slope of said flow signal for decreasing said period when the slope is increasing and increasing said period when the slope is decreasing to provide derivative augmentation of said sample period, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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31. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said sampling signal comprising a series of digital pulses having a pulse width, said processor means monitoring said flow signal to determine a breath rate for increasing said pulse width when breath rate is low and decreasing said pulse width when breath rate is high for providing a variable sample volume, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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32. A metabolic analyzer comprising:
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CO2 detector means for determining a CO2 content of a respired gas; O2 detector means for determining an O2 content of the respired gas; flow detector means for providing a flow signal representative of the flow of the respired gas; flow proportioning valve means for delivering a small, representative and proportional sample of the respired gas having a known volumetrically-proportional relationship with a total volume of the respired gas; pump means for drawing the sample of the respired gas from said flow proportioning valve means and delivering the sample to said CO2 and said O2 detector means; and processor means for converting said flow signal into a sampling signal that is applied to said flow proportioning valve means to provide a sample of respired gas having a known volumetrically-proportional relationship with the total volume of respired gas, said sampling signal comprising a series of digital pulses having a frequency, said processor means monitoring said flow signal for increasing said frequency when said flow signal increases and decreasing said frequency when said flow signal decreases for providing a proportional sample, said processor means determining the total volume of respired gas and said processor means correlating total volume, CO2 content and O2 content to provide a measure of metabolic rate.
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Specification