DETECTING CHEMICAL COMPONENTS FROM SPECTROSCOPIC OBSERVATIONS
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.