System and method for monitoring cardiac output, flow balance, and performance parameters

Abstract

A system for measuring of cardiac output and cardiac performance parameters based on a cardiac blood flow balance parameter between a right chamber of the heart and a left chamber of the heart, includes a sensor device for measuring one of blood pressure and blood flow rate and blood constituent concentration of a patient so as to generate an arterial pulse signal. A processing unit is responsive to the arterial pulse signal for generating a full arterial pulse signal, an arterio-venous pulse signal, and a balance parameter. A computational device is responsive to the balance parameter for further generating cardiac output and a set of cardiac performance parameters. A display station device is responsive to the set of physiological parameters from the computational device for displaying meaningful information.

1 . A method for determining cardiac performance parameters so as to assess a patient's health condition, comprising the processing steps of:
 measuring of one of an aortic pressure signal and a pulmonary arterial pressure signal;   measuring of an electrocardiogram or electrogram waveform signal;   computing of a first derivative of the measured aortic or pulmonary arterial pressure signal;   determine a heart valve opening event using the maximum peak of the first derivative of the measured aortic or pulmonary arterial pressure signal;   determine a heart valve closing event using the minimum valley of the first derivative of the measured aortic or pulmonary arterial pressure signal;   optionally determine an end systolic pressure event and value using the maximum of the measured one of aortic pressure, pulmonary arterial pressure, and ventricular pressure signal;   calculating a full arterial pulse waveform signal from the said measured aortic or pulmonary arterial pressure signal, defined as the aortic or pulmonary artery pressure signal without the effect of atrial diastolic blood flow demand;   calculating an arterio-venous pulse waveform signal by the subtraction of the said measured aortic or pulmonary arterial pressure signal from the said full arterial pulse waveform signal;   determining a pre-diastolic end-systolic pressure (PDPES) event, defined by the ventricular pressure post the isovolemic relaxation phase and prior to diastolic expansion, which is substantially coincident in time with the end of the arterio-venous pulse;   optionally calculating a Left-Right Balance or Right-Left Balance parameter based upon the full arterial pulse and the arterio-venous pulse waveform signals;   determining an end-diastolic pressure (PED) event, defined by the ventricular pressure post diastolic expansion and pre-isovolemic contraction phase, which is substantially coincident in time with the R-wave event in the electrocardiogram or electrogram waveform signal;   calculating a first timing differential between end-diastolic pressure (PED) event and the valve opening event;   estimate the end diastolic pressure (PED) value using said first timing differential in extrapolating backwards a first line segment of the measured aortic or pulmonary arterial pressure signal between the valve opening event and short time thereafter;   calculating a second timing differential between the said pre-diastolic end-systolic pressure (PDPES) event and the valve closing event;   estimate the said pre-diastolic end-systolic pressure (PDPES) value using said second timing differential in extrapolating forward a second line segment of the measured aortic or pulmonary arterial pressure signal between the valve closing event and short time therebefore;   
     
     
         2 . A method for determining cardiac performance parameters as claimed in  claim 1 , further including the step of using the end diastolic pressure (PED) and the pre-diastolic end-systolic pressure (PDPES) values to assess cardiac ventricular end diastolic volume and end systolic volume. 
     
     
         3 . A method for determining cardiac performance parameters as claimed in  claim 2 , further including the step of using the end diastolic pressure and the pre-diastolic end-systolic pressure (PDPES) values to calculate ejection fraction and using cardiac ventricular end diastolic volume and end systolic volume to calculate cardiac output. 
     
     
         4 . A method for determining cardiac performance parameters as claimed in  claim 3 , wherein the ejection fraction EF is equal to 1−PDPES/PED, where PDPES is the pre-diastolic end-systolic pressure value and PED is the end-diastolic pressure value. 
     
     
         5 . A method for determining cardiac performance parameters as claimed in  claim 4 , further including the step of determining cardiac ventricular end diastolic volume and end systolic volume based upon measuring the ventricular volume at end-systolic and end-diastolic events for a calibration. 
     
     
         6 . A method for determining cardiac performance parameters as claimed in  claim 5 , further including the step of calculating the volume to static pressure conversion as a linear scale ratio R defined by (VED−VES)/(PED−PDPES), where PED is the end diastolic pressure value, PDPES is the pre-diastolic end-systolic pressure value, VED is the cardiac ventricular end diastolic volume and VES is the cardiac ventricular end systolic volume. 
     
     
         7 . A method for determining cardiac performance parameters as claimed in  claim 6 , further including the steps of continuously estimating the end diastolic volume VEDest to be equal to R*PED and continuously estimating the end systolic volume VESest to be equal to R*PDPES. 
     
     
         8 . A method for determining cardiac performance parameters as claimed in  claim 7 , further including the step of continuously estimating stroke volume SV to be equal to the difference between the estimated end diastolic volume and the estimated end systolic volume VEDest−VESest. 
     
     
         9 . A method for determining cardiac performance parameters as claimed in  claim 8 , further including the step of continuously estimating cardiac output CO to be equal to the stroke volume SV*HR, where HR is the heart rate. 
     
     
         10 . A method for determining cardiac performance parameters as claimed in  claim 9 , further including the step of calculating cardiac output index CI to be equal to the cardiac output CO divided by BSA, where BSA is the body surface area. 
     
     
         11 . A method for determining cardiac performance parameters as claimed in  claim 1 , further including the step of calculating mean arterial pressure MAP. 
     
     
         12 . A method for determining cardiac performance parameters as claimed in  claim 11 , further including the step of calculating systemic vascular resistance SVR to be equal to the difference between the mean arterial pressure MAP and a central venous pressure CVP, which is then divided by the cardiac output CO. 
     
     
         13 . A method for determining cardiac performance parameters as claimed in  claim 8 , further including the step of calculating stroke work SW to be equal to the stroke volume SV times the mean arterial pressure MAP. 
     
     
         14 . A method for determining cardiac performance parameters as claimed in  claim 3 , further including the step of calculating contractility by using the derivative of the ejection fraction EF. 
     
     
         15 . A method for determining cardiac performance parameters as claimed in  claim 6 , further including the step of using the linear scale ratio R computed for one ventricular chamber's volume to estimate the other ventricular chamber's volume and its cardiac performance parameters. 
     
     
         16 . A method for determining cardiac performance parameters as claimed in  claim 1 , further comprising the steps of providing a processor unit and configuring the processor unit to perform all said processing steps. 
     
     
         17 . A method for determining cardiac performance parameters as claimed in  claim 16 , wherein said processor unit is comprised of microprocessor. 
     
     
         18 . A method for producing an aortic pulse waveform, defined by measurement of one of blood pressure, blood flow, or blood constituent concentration, comprising the processing steps of:
 measuring simultaneously of an aortic pulse waveform and an arterial pulse waveform;   calculating of a full aortic pulse waveform, defined as the aortic pulse waveform without the effect of atrial diastolic blood flow demand, and a full arterial pulse waveform, respectively, defined as the arterial pulse waveform without the effect of atrial diastolic blood flow demand;   calculating of an aortic arterio-venous pulse waveform, defined by subtraction of measured aortic pulse waveform from said full aortic pulse waveform, and an arterial arterio-venous pulse waveform, defined by subtraction of measured arterial pulse waveform from said full arterial pulse waveform;   utilizing a system identification to produce a state-space linear model to define a transfer function relationship between the full arterial pulse waveform as an input and the full aortic pulse waveform as an output;   utilizing the transfer function relationship with continuous input full arterial pulse waveform to estimate the output full aortic pulse waveform;   utilizing a system identification to produce a state-space linear model to define a transfer function relationship between the arterial arterio-venous pulse waveform as an input and the aortic arterio-venous pulse waveform as an output;   utilizing the transfer function relationship with continuous input arterial arterio-venous pulse waveform to estimate the output aortic arterio-venous pulse waveform; and   estimating of the aortic pulse waveform by subtracting the estimated aortic arterio-venous pulse waveform from the estimated full aortic pulse waveform.   
     
     
         19 . The method claim of  18 , wherein the aortic pulse is replaced with a pulmonary artery pulse and the said peripheral arterial pulse is replaced by a peripheral pulmonary arterial branch pulse. 
     
     
         20 . A method for producing an aortic pulse waveform as claimed in  claim 18 , further comprising the steps of providing a processor unit and configuring the processor unit to perform all said processing steps. 
     
     
         21 . A method for determining cardiac performance parameters as claimed in  claim 20 , wherein said processor unit is comprised of microprocessor. 
     
     
         22 . A method for estimating cardiac output of the left or right ventricular chamber using measured cardiac output from a right or left ventricular chamber, respectively, adjusted using a balance parameter;
 the cardiac output being adjusted using one of a Left-Right Balance (LRB) parameter and a Right-Left Balance (RLB) parameter.   
     
     
         23 . The method claim of  claim 22 , wherein said estimating of the left ventricle's cardiac output (LCO) is equal to the right ventricle's cardiac output (RCO) divided by (1−the Right-Left Balance (RLB) parameter. 
     
     
         24 . The method claim of  claim 22 , wherein said estimating of the right ventricle's cardiac output (RCO) is equal to the left ventricle's cardiac output (LCO) multiplied by the Left-Right Balance (LRB) parameter.