Pulse contour method and apparatus for continuous assessment of a cardiovascular parameter
First Claim
1. A method for determining a cardiovascular parameter equal to or derivable from cardiac output (CO) comprising:
- inputting a current pressure waveform data set corresponding to arterial blood pressure over a current pressure cycle;
determining defining parameters of an assumed input flow waveform as a function of a peripheral resistance value determined for at least one previous pressure cycle;
determining model parameters of a model of a relationship between the assumed input flow waveform and the current pressure waveform data set;
computing a current peripheral resistance value as a function of the model parameters; and
computing an estimate of the cardiovascular parameter as a function of the current peripheral resistance value and the current pressure waveform data set.
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Abstract
A cardiovascular parameter such as cardiac output is estimated from a current pressure waveform data set without needing to directly measure blood flow or arterial compliance. The general shape of an input flow waveform over one beat-to-beat cycle is assumed (or computed), and then the parameters of a flow-to-pressure model, if not pre-determined, are determined using system identification techniques. In one embodiment, the parameters thus determined are used to estimate a current peripheral resistance, which is used not only to compute an estimate of the cardiovascular parameter, but also to adjust the shape of the input flow waveform assumed during at least one subsequent beat-to-beat cycle. Another embodiment does not require computation of the peripheral resistance and still another embodiment computes a flow estimate from an optimized identification of the parameters defining the assumed input flow waveform.
32 Citations
21 Claims
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1. A method for determining a cardiovascular parameter equal to or derivable from cardiac output (CO) comprising:
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inputting a current pressure waveform data set corresponding to arterial blood pressure over a current pressure cycle; determining defining parameters of an assumed input flow waveform as a function of a peripheral resistance value determined for at least one previous pressure cycle; determining model parameters of a model of a relationship between the assumed input flow waveform and the current pressure waveform data set; computing a current peripheral resistance value as a function of the model parameters; and computing an estimate of the cardiovascular parameter as a function of the current peripheral resistance value and the current pressure waveform data set. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for determining a cardiovascular value equal to or derivable from cardiac output (CO) comprising:
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an arrangement generating a current pressure waveform data set corresponding to arterial blood pressure over a current pressure cycle; a processing system including; an input flow waveform generation module comprising computer-executable code for determining defining parameters of an assumed input flow waveform as a function of a peripheral resistance value determined for at least one previous pressure cycle; a system parameter identification module comprising computer-executable code for determining model parameters of a model of a relationship between the assumed input flow waveform and the current pressure waveform data set; a model parameter computation module comprising computer-executable code for computing a current peripheral resistance value as a function of the model parameters; and a cardiovascular value computation module comprising computer-executable code for computing an estimate of the cardiovascular parameter as a function of the current peripheral resistance value and the current pressure waveform data set. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification