Cardiac output detection by multiple frequency thermodilution
First Claim
1. Apparatus for cardiac thermodilution measurement comprising:
- means for applying a traceable signal by injection of thermal energy for dilution in the blood flow in a location upstream of a heart output conduit;
means for varying the magnitude of the traceable signal as a function of time at at least two frequencies thereby varying the amount of thermal energy applied to the blood flow;
means for detecting said traceable signal as blood flow temperature downstream of the heart ventricle at the first of said at least two frequencies; and
means for separately detecting at least the second of said at least two frequencies in said traceable signal as blood flow temperature downstream of the ventricle of said heart.
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Abstract
Method and apparatus for measuring cardiac output in which a traceable signal in the form of thermal energy or an injectate is applied to the blood flow through the heart having a plurality of frequency components with the traceable signal detected at a heart output vessel and analyzed at the plural frequency components to provide cardiac output rate and ejection fraction information. The traceable signal is preferably heat energy applied as a very low frequency modulation of a high frequency signal at a fundamental and further harmonic or as a square wave in which multiple harmonics are present. At least two frequency components of the square wave are then separately analyzed. A multiple frequency system in addition to permitting analysis of previously undetectable heart output characteristics additionally permits determination of whether the source of the traceable signal is properly located within the heart such as in the ventricle.
80 Citations
14 Claims
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1. Apparatus for cardiac thermodilution measurement comprising:
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means for applying a traceable signal by injection of thermal energy for dilution in the blood flow in a location upstream of a heart output conduit; means for varying the magnitude of the traceable signal as a function of time at at least two frequencies thereby varying the amount of thermal energy applied to the blood flow; means for detecting said traceable signal as blood flow temperature downstream of the heart ventricle at the first of said at least two frequencies; and means for separately detecting at least the second of said at least two frequencies in said traceable signal as blood flow temperature downstream of the ventricle of said heart. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for detecting pump output characteristics in a pump of the type having a chamber of reducible volume which is periodically reduced and expanded in a cyclical fashion at a known rate along with inlet and outlet conduits and corresponding valves to promote the flow of a fluid material in a predetermined direction from said inlet to said outlet conduit, a process for detecting flow characteristics comprising:
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applying a traceable signal in the form of thermal energy or an injectate varying in magnitude at a first and at least a second distinct frequency to the reducible volume of said chamber at a first location to mix with and be diluted by said fluid material; detecting in said outlet at a second location downstream of said first location said traceable signal as mixed with and diluted by said fluid material at said first frequency; detecting in said outlet conduit said traceable signal as mixed with and diluted by said fluid material at at least second frequency.
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12. Apparatus for cardiac thermodilution measurement comprising:
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means for applying a traceable signal by injection of thermal energy for dilution in the blood flow in a location upstream of a heart output conduit; means for varying the magnitude of the traceable signal as a function of time at at least two frequencies thereby varying the amount of thermal energy applied to the blood flow; means for detecting said traceable signal as blood flow temperature downstream of the heart ventricle at the first of said at least two frequencies; and means for separately detecting at least the second of said at least two frequencies in said traceable signal as blood flow temperature downstream of the ventricle of said heart.
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13. A process for detecting flow output characteristics of a fluid material through a chamber with a mixing volume having an outlet conduit, said process for detecting flow output characteristics comprising:
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applying a traceable signal in the form of thermal energy or an injectate varying in magnitude at a first and at least a second distinct frequency to the mixing volume of said chamber; detecting in said outlet conduit at a second location downstream of said first location said traceable signal as mixed with and diluted by said fluid material at said first frequency; detecting in said outlet conduit said traceable signal as mixed with and diluted by said fluid material at at least said second frequency.
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14. A process for detecting pump output characteristics in a pump of the type having a chamber of reducible volume which is periodically reduced and expanded in a cyclical fashion at a known rate along with inlet and outlet conduits and corresponding valves to promote the flow of a fluid material in a predetermined direction from said inlet to said outlet conduit, a process for detecting flow characteristics comprising:
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applying a traceable signal in the form of thermal energy or an injectate varying in magnitude at a first and at least a second distinct frequency to the reducible volume of said chamber at a first location to mix with and be diluted by said fluid material; detecting in said outlet conduit at a second location downstream of said first location said traceable signal as mixed with and diluted by said fluid material at said first frequency; detecting in said outlet conduit said traceable signal as mixed with and diluted by said fluid material at at least second frequency.
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Specification