Methods and apparatus for determining arterial pulse wave velocity
First Claim
1. A method for determining an arterial pulse transit time of a subject, comprising:
- measuring a proximal waveform indicative of blood pressure at a proximal site of the subject using a first sensor;
measuring a distal waveform indicative of blood pressure at a distal site of the subject using a second sensor;
defining a dynamic system that relates one of the waveforms to the other waveform in terms of unknown parameters of a parametric mathematical model that assumes a specific structure for the dynamic system, where one of the unknown parameters accounts for wave reflection and another of the unknown parameters accounts for pulse transit time;
determining the unknown parameters of the mathematical model from the measured proximal waveform and the measured distal waveform; and
determining a pulse transit time between the proximal site and the distal site using the determined parameters from the mathematical model, where the steps of determining the unknown parameters of the mathematical model and determining a pulse transit time are implemented by a computer processor of a computing device.
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Accused Products
Abstract
Methods are presented for determining pulse transit time (PTT) and/or pulse wave velocity (PWV) of a subject by application of parametric system identification to proximal and distal arterial waveforms. The two waveforms are measured from the subject. A system is defined that relates the proximal arterial waveform to the distal arterial waveform (or vice versa) in terms of the unknown parameters of a parametric mathematical model. The model parameters are determined from the measured waveforms using system identification. PTT between the proximal and distal arterial sites is then determined from the system model. PWV may also be determined by dividing the distance between measurement sites (D) by PTT.
16 Citations
24 Claims
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1. A method for determining an arterial pulse transit time of a subject, comprising:
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measuring a proximal waveform indicative of blood pressure at a proximal site of the subject using a first sensor; measuring a distal waveform indicative of blood pressure at a distal site of the subject using a second sensor; defining a dynamic system that relates one of the waveforms to the other waveform in terms of unknown parameters of a parametric mathematical model that assumes a specific structure for the dynamic system, where one of the unknown parameters accounts for wave reflection and another of the unknown parameters accounts for pulse transit time; determining the unknown parameters of the mathematical model from the measured proximal waveform and the measured distal waveform; and determining a pulse transit time between the proximal site and the distal site using the determined parameters from the mathematical model, where the steps of determining the unknown parameters of the mathematical model and determining a pulse transit time are implemented by a computer processor of a computing device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for determining an arterial pulse wave velocity of a subject, comprising:
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measuring a proximal waveform indicative of the arterial pulse at a proximal site of the subject using a first sensor; measuring a distal waveform indicative of the arterial pulse at a distal site of the subject using a second sensor; defining a dynamic system for the subject that relates one of the waveforms to the other waveform in terms of unknown parameters of a physical tube-load model transfer function in which pulse transit time is an explicit parameter of the model; determining the parameters of the transfer function from the measured proximal and the measured distal waveforms; and determining a pulse wave velocity from the pulse transit time parameter, where the steps of determining the parameters of the transfer function and determining a pulse transit velocity are implemented by a computer processor of a computing device. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method for tracking blood pressure of a subject, comprising:
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measuring a proximal waveform indicative of the arterial pulse at a proximal site of the subject using a first sensor; measuring a distal waveform indicative of the arterial pulse at a distal site of the subject using a second sensor; defining a dynamic system that relates the proximal arterial waveform to the distal arterial waveform in terms of a mathematical model, where one parameter of the mathematical model accounts for wave reflection and another parameter of the mathematical model accounts for pulse transit time; determining the mathematical model for the subject from the measured waveforms; determining a pulse transit time between the proximal site and the distal site from the mathematical model, where the steps of determining the mathematical model and determining a pulse transit time are implemented by a computer processor of a computing device; and tracking blood pressure by mapping the pulse transit time through a calibration curve that relates pulse transit time to blood pressure of the subject. - View Dependent Claims (20)
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21. A method for improving a cardiac output measure of a subject, comprising:
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measuring a waveform indicative of the arterial pulse at a proximal site of the subject using a first sensor; measuring a waveform indicative of the arterial pulse at a distal site of the subject using a second sensor; defining a dynamic system that relates the proximal arterial waveform to the distal arterial waveform in terms of a mathematical model, where one parameter of the mathematical model accounts for wave reflection and another parameter of the mathematical model accounts for pulse transit time; determining the mathematical model from the measured waveforms; determining a pulse transit time between the proximal site and the distal site from the mathematical model where the steps of determining the mathematical model and determining a pulse transit time are implemented by a computer processor of a computing device; and improving a cardiac output measure for the subject using the pulse transit time. - View Dependent Claims (22, 23, 24)
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Specification