Detecting chemical components from spectroscopic observations

Abstract

Embodiments disclosed herein may include methods and systems capable of estimating the underlying concentrations of chromophores in a sample. The photon scattering and absorption model may be based on Laplace and stable distributions, which may reveal that measurements in diffuse reflectance may follow a Beer-Lambert and Kohlrausch-Williams-Watts (KWW) product. This Beer-Lambert portion of the product may dominate in high absorption sample areas, while the KWW portion of the product may dominate in low absorption sample areas.

1 . A method for determining the concentration of a component in a tissue sample of a patient, comprising:
 collecting a plurality of physiologic signals from a tissue sample of a patient;   measuring, for each physiologic signal, a concentration of a component of the tissue sample; and   performing a Kernel Partial Least Squares regression on the concentration of the component.   
     
     
         2 . The method of  claim 1 , comprising determining a model for the tissue sample based at least in part upon the Kernel Partial Least Squares regression. 
     
     
         3 . The method of  claim 2 , comprising applying the model to a second tissue sample. 
     
     
         4 . The method of  claim 2 , wherein the model comprises a nonlinear model. 
     
     
         5 . The method of  claim 1 , comprising calculating a kernel function for use with the Kernel Partial Least Squares regression. 
     
     
         6 . The method of  claim 1 , wherein collecting the plurality of physiologic signals comprises:
 emitting light into the tissue of the patient;   detecting scattered or reflected light from the tissue; and   generating the plurality of physiologic signals corresponding to the detected light.   
     
     
         7 . The method of  claim 1 , wherein the concentration comprises a concentration of chromophores in the tissue sample. 
     
     
         8 . A system for determining the concentration of a component in a patient's tissue, comprising:
 a sensor configured to obtain a plurality of physiologic signals from a patient;   a monitor configured to receive from the sensor the plurality of physiologic signals; and   a processor configured to:
 measure, for each physiologic signal, a concentration of a component of the tissue; and 
 perform a Kernel Partial Least Squares regression on the concentration of the component. 
   
     
     
         9 . The system of  claim 8 , wherein the sensor is configured to emit light into a tissue of the patient and to detect scattered or reflected light from the tissue. 
     
     
         10 . The system of  claim 9 , wherein the plurality of physiologic signals corresponds to the detected light. 
     
     
         11 . The system of  claim 8 , wherein the monitor comprises a pulse oximeter. 
     
     
         12 . The system of  claim 8 , wherein the processor is configured to determine a model for the tissue based at least in part upon the Kernel Partial Least Squares regression. 
     
     
         13 . The system of  claim 12 , wherein the processor is configured to apply the model to a second tissue sample. 
     
     
         14 . The system of  claim 12 , wherein the model comprises a nonlinear model. 
     
     
         15 . The system of  claim 8 , wherein the processor is configured to calculate a kernel function for use with the Kernel Partial Least Squares regression. 
     
     
         16 . The system of  claim 8 , further comprising a memory device coupled to the processor and storing an assumption regarding the tissue, for use in the Kernel Partial Least Squares regression. 
     
     
         17 . The system of  claim 8 , wherein the concentration comprises a concentration of chromophores in the tissue. 
     
     
         18 . A medical device for determining the concentration of a component in a tissue sample, comprising:
 a processor configured to:
 collect a plurality of physiologic signals from a tissue sample of a patient; 
 measure, for each physiologic signal, a concentration of a component of the tissue sample; and 
 perform a Kernel Partial Least Squares regression on the concentration of the component. 
   
     
     
         19 . The medical device of  claim 18 , wherein the processor is configured to determine a model for the tissue sample based at least in part upon the Kernel Partial Least Squares regression. 
     
     
         20 . The medical device of  claim 19 , wherein the processor is configured to apply the model to a second tissue sample. 
     
     
         21 . The medical device of  claim 18 , wherein the medical device comprises a pulse oximeter. 
     
     
         22 . A method for determining a chromophore concentration in a tissue area of a patient, comprising:
 emitting electromagnetic radiation into a tissue area of a patient;   detecting radiation scattered and/or reflected by the tissue area;   generating a physiologic signal corresponding to the detected radiation;   collecting a plurality of data samples from the signal;   measuring, for each data sample, an affine function of a chromophore concentration; and   performing a Kernel Partial Least Squares regression to obtain a model for the tissue area.