Methods and systems for photoacoustic monitoring using indicator dilution
First Claim
Patent Images
1. A method for determining a physiological parameter of a subject, the method comprising:
- providing a photonic signal to a first blood vessel site of the subject;
detecting an acoustic pressure signal from the first blood vessel site using one or more acoustic detectors, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided at a temperature different than the temperature of the second blood vessel site; and
determining cardiac output of the subject based on an initial indicator temperature, an initial blood temperature at a first time, and an adjusted blood temperature at a second time as indicated by the thermo-dilution response and based on an equation having the form;
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Abstract
A patient monitoring system may provide photoacoustic sensing based on an indicator dilution to determine one or more physiological parameters of a subject. The system may detect an acoustic pressure signal, which may include one or more thermo-dilution responses, one or more hemo-dilution responses, or a combination thereof. For example, a thermo-dilution indicator and/or a hemo-dilution indicator may be used to determine one or more hemodynamic parameters. In a further example, an isotonic indicator and a hypertonic indicator may be used to determine one or more hemodynamic parameters of the subject.
54 Citations
20 Claims
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1. A method for determining a physiological parameter of a subject, the method comprising:
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providing a photonic signal to a first blood vessel site of the subject; detecting an acoustic pressure signal from the first blood vessel site using one or more acoustic detectors, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided at a temperature different than the temperature of the second blood vessel site; and determining cardiac output of the subject based on an initial indicator temperature, an initial blood temperature at a first time, and an adjusted blood temperature at a second time as indicated by the thermo-dilution response and based on an equation having the form; - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for determining a physiological parameter of a subject, the system comprising:
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a light source configured to provide a photonic signal to a first blood vessel site of the subject; an acoustic detector configured to detect an acoustic pressure signal from the first blood vessel site, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided to the second blood vessel site at a temperature different than the temperature of the second blood vessel site; and processing equipment configured to determine cardiac output of the subject based on an initial indicator temperature, an initial blood temperature at a first time, and an adjusted blood temperature at a second time as indicated by the thermo-dilution response and based on an equation having the form; - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for determining a physiological parameter of a subject, the method comprising:
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providing a photonic signal to a first blood vessel site of the subject; detecting an acoustic pressure signal from the first blood vessel site using one or more acoustic detectors, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided at a temperature different than the temperature of the second blood vessel site; and determining cardiac output of the subject based only on; a proportionality constant related to the effects of specific gravity and heat capacity of blood, the indicator, or both; an initial indicator temperature; an initial blood temperature at a first time; an adjusted blood temperature at a second time as indicated by the thermo-dilution response; and a volume of the indicator provided to the second blood vessel site.
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18. A method for determining a physiological parameter of a subject, the method comprising:
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providing a photonic signal to a first blood vessel site of the subject; detecting an acoustic pressure signal from the first blood vessel site using one or more acoustic detectors, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided at a temperature different than the temperature of the second blood vessel site; determining cardiac output of the subject based on an initial indicator temperature, an initial blood temperature at a first time, and an adjusted blood temperature at a second time as indicated by the thermo-dilution response; and determining one or more of intrathoracic blood volume, intrathoracic circulatory volume, global end-diastolic volume, pulmonary circulatory volume, and extravascular lung water based on the cardiac output and one or more features of a thermo-dilution curve that is representative of the thermo-dilution response, wherein the features comprise a mean transit time of the thermo-dilution curve or a downslope time of the thermo-dilution curve.
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19. A system for determining a physiological parameter of a subject, the system comprising:
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a light source configured to provide a photonic signal to a first blood vessel site of the subject; an acoustic detector configured to detect an acoustic pressure signal from the first blood vessel site, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided to the second blood vessel site at a temperature different than the temperature of the second blood vessel site; and processing equipment configured to determine cardiac output of the subject based only on; a proportionality constant related to the effects of specific gravity and heat capacity of blood, the indicator, or both; an initial indicator temperature; an initial blood temperature at a first time; an adjusted blood temperature at a second time as indicated by the thermo-dilution response; and a volume of the indicator provided to the second blood vessel site.
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20. A system for determining a physiological parameter of a subject, the system comprising:
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a light source configured to provide a photonic signal to a first blood vessel site of the subject; an acoustic detector configured to detect an acoustic pressure signal from the first blood vessel site, wherein the acoustic pressure signal is caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site, and wherein the acoustic pressure signal comprises a thermo-dilution response corresponding to an indicator provided to a second blood vessel site, wherein the indicator is provided to the second blood vessel site at a temperature different than the temperature of the second blood vessel site; and processing equipment configured to; determine cardiac output of the subject based on an initial indicator temperature, an initial blood temperature at a first time, and an adjusted blood temperature at a second time as indicated by the thermo-dilution response; and determine one or more of intrathoracic blood volume, intrathoracic circulatory volume, global end-diastolic volume, pulmonary circulatory volume, and extravascular lung water based on the cardiac output and one or more features of a thermo-dilution curve that is representative of the thermo-dilution response, wherein the features comprise a mean transit time of the thermo-dilution curve or a downslope time of the thermo-dilution curve.
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Specification