Method and system for determining cardiac performance

Abstract

Methods and associated algorithms for determining cardiac and/or cardiovascular performance that are based on at least one cardiac function determinant associated with or at least in part, reflective of preload, contractility and afterload.

1 . A method for determining the cardiac performance of a subject, comprising the steps of:
 providing a first cardiac function determinant associated with preload;   providing a second cardiac function determinant associated with contractility;   providing a third cardiac function determinant associated with afterload; and   determining cardiac performance of the subject from said first, second and third cardiac function determinants and according to the formula
     CP=f ( CFD   x   ;CFD   y   ;CFD   z ) 
   
     wherein CP represents said cardiac performance, CFD x  represents said first cardiac function determinant, CFD y  represents said second cardiac function determinant, CFD z  represents said third cardiac function determinant, and f(CFD z ; CFD y ; CFD z ) represents an empirical relationship between CFD x , CFD y , and CFD z . 
   
   
       2 . The method of  claim 1 , wherein said cardiac performance comprises a functional characteristic selected from the group consisting of cardiac stroke volume, cardiac output, cardiac stroke index, systemic vascular resistance, perfusion, systolic blood pressure, degree of stenosis, blood volume, arterial pressure, hematocrit, and oxygen delivery. 
   
   
       3 . The method of  claim 2 , wherein said cardiac stroke index is determined according to the formula
     SI=α*LVET/PEP *(1−β)*( dv/dt   e,s )/( dv/dt   f,s )*(( dv/dt   e,s )/( dv/dt   e,d )))   
     wherein SI represents said cardiac stroke index, LVET represents left ventricular ejection time, PEP represents a pre-ejection period, α and β represent variable constants that are measurement system-specific, dv/dt e,s  represents the maximal systolic upslope of a plethysmogram signal obtained at an ear, dv/dt f,s  represents the maximal systolic upslope of a plethysmogram signal obtained at a finger, and dv/dt e,d  represents the maximal diastolic down slope of said ear plethysmogram signal. 
   
   
       4 . The method of  claim 2 , wherein said cardiac performance comprises systolic blood pressure, and wherein said first cardiac function determinant is determined from the width measured in seconds of the ejection phase of plethysmogram data, said second cardiac function determinant is determined from a normalized maximal rate of change of the systolic upslope of the ejection phase and measured in 1/seconds, and said third cardiac function determinant is determined from a normalized rate of change of the systolic upslope at the inflection point and measured in 1/seconds. 
   
   
       5 . A method for determining the cardiac performance of a subject, comprising the steps of:
 providing a first plurality of cardiac function determinants associated with preload;   providing a second plurality of cardiac function determinants associated with contractility;   providing a third plurality of cardiac function determinants associated with afterload; and   determining cardiac performance of the subject from said first, second and third plurality of cardiac function determinants and according to the formula
     CP=f   co ( CFD   (c)x   ;CFD   (c)y   ;CFD   (c)z ) 
   
     wherein CP represents said cardiac performance, CFD (c)x  represents a combination of said first plurality of cardiac function determinants, CFD (c)y  represents a combination of said second plurality of cardiac function determinants, CFD (c)z  represents a combination of said third plurality of cardiac function determinants, and f co  represents a combination of empirical relationships that combine CFD (c)x , CFD (c)y , and CFD (c)z . 
   
   
       6 . The method of  claim 5 , wherein said cardiac performance comprises a functional characteristic selected from the group consisting of cardiac stroke volume, cardiac output, cardiac stroke index, systemic vascular resistance, perfusion, systolic blood pressure, degree of stenosis, blood volume, arterial pressure, hematocrit, and oxygen delivery.