Method and apparatus for determining cardiac output or total peripheral resistance
AssigneeDuncan Campbell Patents Pty. Ltd.
InventorDuncan Campbell
Life of this patent
Estimating the term…
Abstract
A method and apparatus determines continuously mean cardiac output by measuring the arterial pressure e.g. at a finger and calculating therefrom the mean arterial pressure and the time constant of the arterial system (in diastole). Compliance values are provided from a table. Mean cardiac output is then the product of mean arterial pressure and compliance divided by the time constant. Changes in cardiac output can be used for diagnostic purposes. A pressure cuff or pressure tonometer can be used to measure the arterial pressure with a microcomputer providing the necessary calculations.
Claims25
A method for deriving cardiac output in a patient comprising the steps of:
- measuring continuously the arterial pressure at a point within the cardiovascular system to derive an arterial pressure waveform;
- determining the mean arterial pressure from said arterial pressure waveform;
- determining the compliance of the arterial system for the patient;
- determining the time constant of the arterial system from the arterial pressure waveform and deriving the mean cardiac output as the product of the mean arterial pressure and compliance divided by said time constant.
An apparatus for deriving cardiac output in a patient including means for continuously measuring arterial pressure at a point within the cardiovascular system;
- means for processing said measured arterial pressure including means for calculating the mean arterial pressure;
- means for inputting compliance values;
- and means for measuring the time constant of the arterial system from said measured arterial pressure;
- and means for calculating cardiac output as the product of mean arterial pressure and compliance divided by said time constant, and further including means for displaying at least said arterial pressure and said cardiac output.
A method for deriving cardiac output comprising the steps of:
- measuring continuously a patient's arterial pressure at a point within the patient's cardiovascular system for deriving an arterial pressure waveform;
- determining compliance of the patient's arterial system;
- determining a time constant of the patient's arterial system from the arterial pressure waveform and deriving peripheral resistance as said time constant divided by said compliance;
- and,
- determining mean arterial pressure from said arterial pressure waveform and deriving mean cardiac output as a product of said peripheral resistance and said mean arterial pressure.
A method for deriving cardiac output comprising the steps of:
- measuring continuously a patient's arterial pressure at a point within the patient's cardiovascular system for deriving an arterial pressure waveform;
- determining the compliance of the patient's arterial system;
- and,
- determining a time constant of the patient's arterial system from the arterial pressure waveform and deriving peripheral resistance as said time constant divided by said compliance.
Dependencies are inferred from the claim text.