Method for vascular impedance measurement

Claim 1

A method for measuring vascular impedance properties from the blood pressure waveform of a patient, the waveform containing heart beat signals, comprising the steps of: measuring and digitizing an arterial blood pressure of a patient to produce a series of digitized data samples representing a waveform of the arterial blood pressure of the patient; processing a heart beat signal in the digitized blood pressure waveform, marking a segment of the heart beat signal corresponding to systole, and determining an ejection time by measuring the duration of said segment; processing the same series to determine a mean arterial pressure of the patient; processing said ejection time and other patient data to determine a cardiac output measurement value for the patient from at least said ejection time and other patient data; and processing the sample series and the cardiac output value and mean arterial pressure to determine for the patient one or more parameters of a vascular impedance model, the parameters being measures of vascular impedance properties.

Claim 2

A method for measuring vascular impedance properties from the blood pressure waveform of a patient, the waveform containing heart beat signals, comprising the steps of: measuring and digitizing an arterial blood pressure of a patient to produce a series of digitized data samples representing a waveform of the arterial blood pressure of the patient; processing a heart beat signal in the digitized blood pressure waveform, marking a segment of the heart beat signal corresponding to systole, and determining an ejection time by measuring the duration of said segment; processing the same series to determine a mean arterial pressure of the patient; processing said ejection time and other patient data to determine a cardiac output measurement value for the patient from at least said ejection time and other patient data; and processing the sample series and the cardiac output value and mean arterial pressure to determine for the patient one or more parameters of a vascular impedance model, the parameters being measures of vascular impedance properties.

Claim 3

A method for measuring vascular impedance properties from the blood pressure waveform of a patient, the waveform containing heart beat signals, comprising the steps of: measuring and digitizing an arterial blood pressure of a patient to produce a series of digitized data samples representing a waveform of the arterial blood pressure of the patient, the waveform containing heart beat signals; processing the heart beat signals in the digitized blood pressure waveform to select a group of representative heart beat signals, said heart beat signals selected according to predetermined criteria whereby unwanted signals are filtered out; processing a heart beat signal in the digitized blood pressure waveform, marking a segment of the heart beat signal corresponding to systole, and determining an ejection time by measuring the duration of said segment; processing at least said ejection time and other patient data to determine a cardiac output measurement value for the patient; and processing the sample series, the cardiac output value and mean arterial pressure to determine for the patient one or more parameters of a vascular impedance model, the parameters being measures of vascular impedance properties.

Claim 4

A method for measuring vascular impedance properties from the blood pressure waveform of a patient, the waveform containing heart beat signals, comprising the steps of: measuring and digitizing an arterial blood pressure of a patient to produce a series of digitized data samples representing a waveform of the arterial blood pressure of the patient, the waveform containing heart beat signals; processing the heart beat signals in the digitized blood pressure waveform to select a group of representative heart beat signals, said heart beat signals selected according to predetermined criteria whereby unwanted signals are filtered out; processing a heart beat signal in the digitized blood pressure waveform, marking a segment of the heart beat signal corresponding to systole, and determining an ejection time by measuring the duration of said segment; processing at least said ejection time and other patient data to determine a cardiac output measurement value for the patient; and processing the sample series, the cardiac output value and mean arterial pressure to determine for the patient one or more parameters of a vascular impedance model, the parameters being measures of vascular impedance properties.

Claim 7

A method for measuring vascular impedance properties from the blood pressure waveform of a patient, the waveform containing heart beat signals, comprising the steps of: measuring and digitizing an arterial blood pressure of a patient to produce a corresponding series of digitized data samples representing a waveform of the arterial blood pressure of the patient; processing the sample series to determine a cardiac output measurement value for the patient; processing heart beat signals in the digitized blood pressure waveform, and marking segments of the heart beat signals corresponding to diastole; and processing the marked diastolic segments of the sample series and the cardiac output value and mean arterial pressure to determine for the patient one or more parameters of a vascular impedance model, the parameters being measures of vascular impedance properties.

Claim 8

A method for measuring vascular impedance properties from the blood pressure waveform of a patient, the waveform containing heart beat signals, comprising the steps of: measuring and digitizing an arterial blood pressure of a patient to produce a corresponding series of digitized data samples representing a waveform of the arterial blood pressure of the patient; processing the sample series to determine a cardiac output measurement value for the patient; processing heart beat signals in the digitized blood pressure waveform, and marking segments of the heart beat signals corresponding to diastole; and processing the marked diastolic segments of the sample series and the cardiac output value and mean arterial pressure to determine for the patient one or more parameters of a vascular impedance model, the parameters being measures of vascular impedance properties.

Claim 11

A method for processing the blood pressure waveform of a patient to determine the condition of a patient's vasculature from the shape of certain portions of the waveform, including at least the compliance of the patient's blood vessels, the waveform containing heart beat signals, comprising the steps of: measuring and converting a blood pressure waveform of the patient to a corresponding analog signal; digitizing the blood pressure waveform signal for a series of the patient's heart beats and storing the signal in a digital storage device; processing the digitized blood pressure waveform signal to: (a) count the number of heart beats per unit time in the digitized blood pressure waveform to produce a heart rate signal for the patient, and (b) search a heart beat signal in the digitized blood pressure waveform, mark events indicating a beginning and ending of systole, and determine an ejection time signal by measuring a time between the marked events; processing the heart rate signal, the ejection time signal, and values representing the patient's age and body surface area to generate an output signal indicative of the patient's cardiac output; processing the digitized blood pressure waveform and determining therefrom a mean arterial pressure signal indicative of the patient's mean arterial pressure; processing the digitized blood pressure waveform and marking segments of the waveform corresponding to a period of diastole in the heart; and processing the marked segments of the digitized blood pressure waveform, the cardiac output signal and the mean arterial pressure signal, to analyze the shape of the marked diastolic segments and determine one or more signals representing a condition of the patient's vasculature from a vascular impedance model, the one or more signals including a least a compliance signal representative of the flexibility of the patient's blood vessels.

Claim 12

A method for processing the blood pressure waveform of a patient to determine the condition of a patient's vasculature from the shape of certain portions of the waveform, including at least the compliance of the patient's blood vessels, the waveform containing heart beat signals, comprising the steps of: measuring and converting a blood pressure waveform of the patient to a corresponding analog signal; digitizing the blood pressure waveform signal for a series of the patient's heart beats and storing the signal in a digital storage device; processing the digitized blood pressure waveform signal to: (a) count the number of heart beats per unit time in the digitized blood pressure waveform to produce a heart rate signal for the patient, and (b) search a heart beat signal in the digitized blood pressure waveform, mark events indicating a beginning and ending of systole, and determine an ejection time signal by measuring a time between the marked events; processing the heart rate signal, the ejection time signal, and values representing the patient's age and body surface area to generate an output signal indicative of the patient's cardiac output; processing the digitized blood pressure waveform and determining therefrom a mean arterial pressure signal indicative of the patient's mean arterial pressure; processing the digitized blood pressure waveform and marking segments of the waveform corresponding to a period of diastole in the heart; and processing the marked segments of the digitized blood pressure waveform, the cardiac output signal and the mean arterial pressure signal, to analyze the shape of the marked diastolic segments and determine one or more signals representing a condition of the patient's vasculature from a vascular impedance model, the one or more signals including a least a compliance signal representative of the flexibility of the patient's blood vessels.