Methods and apparatus for improving time domain relationships between signals obtained from respiration
First Claim
1. A method for improving a time domain relationship between two signals obtained from respiration of a subject, comprising the acts of:
- measuring a first respiratory signal corresponding to a respiratory system;
substantially concurrently measuring a second respiratory signal corresponding to a circulatory system;
generating by a processor a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals;
wherein the act of measuring the first respiratory signal comprises measuring a signal that corresponds to carbon dioxide elimination.
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Abstract
Methods for estimating the volume of the carbon dioxide stores of an individual'"'"'s respiratory tract include determining a carbon dioxide store volume at which a correlation between corresponding signals of carbon dioxide elimination and an indicator of the content of carbon dioxide in blood of the individual is optimized. The estimate of the volume of carbon dioxide stores, which comprises a model of the respiratory tract, or lungs, of the individual, may be used as a transformation to improve the accuracy of one or both of the carbon dioxide elimination and carbon dioxide content signals. Transformation, or filtering, algorithms are also disclosed, as are systems in which the methods and algorithms may be used. The methods, algorithms, and systems may be used to accurately and noninvasively determine one or both of the pulmonary capillary blood flow and cardiac output of the individual.
44 Citations
25 Claims
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1. A method for improving a time domain relationship between two signals obtained from respiration of a subject, comprising the acts of:
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measuring a first respiratory signal corresponding to a respiratory system; substantially concurrently measuring a second respiratory signal corresponding to a circulatory system; generating by a processor a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals; wherein the act of measuring the first respiratory signal comprises measuring a signal that corresponds to carbon dioxide elimination. - View Dependent Claims (2)
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3. A method for improving a time domain relationship between two signals obtained from respiration of a subject, comprising the acts of:
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measuring a first respiratory signal corresponding to a respiratory system; substantially concurrently measuring a second respiratory signal corresponding to a circulatory system; generating by a processor a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the act of generating the filter comprises using an algorithm that employs a transformation coefficient based on at least a functional residual capacity of the subject including carbon dioxide stores of the subject. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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11. A method for improving a time domain relationship between two signals obtained from respiration of a subject, comprising the acts of:
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measuring a first respiratory signal corresponding to a respiratory system; substantially concurrently measuring a second respiratory signal corresponding to a circulatory system; generating by a processor a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals; and optimizing the filter, wherein the act of optimizing comprises the act of determining an optimal value for the transformation coefficient. - View Dependent Claims (12)
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13. A method for improving a time domain relationship between two signals obtained from respiration of a subject, comprising the acts of:
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measuring a first respiratory signal corresponding to a respiratory system; substantially concurrently measuring a second respiratory signal corresponding to a circulatory system; generating by a processor a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the act of generating the filter comprises generating a filter that effectively delays the first respiratory signal.
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14. A method for improving a time domain relationship between two signals obtained from respiration of a subject, comprising the acts of:
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measuring a first respiratory signal corresponding to a respiratory system; substantially concurrently measuring a second respiratory signal corresponding to a circulatory system; generating by a processor a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the act of generating the filter comprises generating a filter that effectively advances the second respiratory signal.
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15. A respiratory monitoring device configured to improve a time domain relationship between a first respiratory signal that corresponds to a respiratory system and substantially concurrently obtained second respiratory signal that corresponds to a circulatory system, comprising:
at least one processing element programmed to generate a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein generating the filter comprises generating a filter that effectively delays the first respiratory signal. - View Dependent Claims (16)
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17. A respiratory monitoring device configured to improve a time domain relationship between a first respiratory signal that corresponds to a respiratory system and substantially concurrently obtained second respiratory signal that corresponds to a circulatory system, comprising:
at least one processing element programmed to generate a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein generating the filter comprises generating a filter that effectively advances the second respiratory signal.
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18. A respiratory monitoring device configured to improve a time domain relationship between a first respiratory signal that corresponds to a respiratory system and substantially concurrently obtained second respiratory signal that corresponds to a circulatory system, comprising:
at least one processing element programmed to generate a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the first respiratory signal comprises a signal that corresponds to carbon dioxide elimination. - View Dependent Claims (19)
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20. A respiratory monitoring device configured to improve a time domain relationship between a first respiratory signal that corresponds to a respiratory system and substantially concurrently obtained second respiratory signal that corresponds to a circulatory system, comprising:
at least one processing element programmed to generate a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the filter comprises an algorithm that employs a transformation coefficient based on at least a functional residual capacity of the subject. - View Dependent Claims (21)
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22. A respiratory monitoring device configured to improve a time domain relationship between a first respiratory signal that corresponds to a respiratory system and substantially concurrently obtained second respiratory signal that corresponds to a circulatory system, comprising:
at least one processing element programmed to generate a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the filter comprises an algorithm that considers an estimate of carbon dioxide excretion for a different breath than a breath from which the first and second signals are obtained. - View Dependent Claims (23, 24)
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25. A respiratory monitoring device configured to improve a time domain relationship between a first respiratory signal that corresponds to a respiratory system and substantially concurrently obtained second respiratory signal that corresponds to a circulatory system, comprising:
at least one processing element programmed to generate a filter comprising an algorithm that employs a transformation coefficient based on carbon dioxide stores of a respiratory tract of the subject to at least one of the first and second respiratory signals, wherein the at least one processing element is further programmed to optimize the filter, and wherein the at least one processing element is programmed to determine an optimal value for the transformation coefficient.
Specification