Patent ID: 7254425
Filing Date: 2007-08-07
Classification: A61B,G01N

Abstract:
1. A method for identifying artifacts in optical measurements conducted for the purpose of determination of concentration of an analyte in a tissue, or value of a physiological parameter, or a combination of the forgoing, the method comprising the steps of: (a) providing an apparatus for measuring at least one optical property of the tissue; (b) introducing electromagnetic radiation at at least one wavelength into the tissue by means of the apparatus; (c) collecting optical data from the tissue over a selected period of time; (d) introducing the collected data into an algorithm to identify an artifact in the optical data, the artifact resulting from movement of the probe or the tissue during a brief period of time; and (e) determining whether an artifact has appeared in the optical data, wherein the algorithm utilizes equations for calculating a set of values from the optical data, which optical data comprise a plurality of data points, the equations comprising: Where: N=effective quantity of data points in the moving average for the algorithm (N=value greater than 1, as specified by user) Dc=artifact threshold value for D(i) (Dc=value greater than 0, as specified by user) P=algorithm constant (P=2/[N+1]) i=current data point number (i is greater than 1) X(i)=value of the current data point X(i−1)=value of the previous data point X(1)=value of the first data point S(i)=value of slope parameter at the current data point S(i−1)=value of slope parameter at the previous data point S(1)=value of slope parameter at the first data point (S(1)=0) A(i) =value of moving average at the current data point A(i−1)=value of moving average at the previous data point A(1)=value of moving average at the first data point (A(1)=X(1)) D(i)=absolute difference between X(i) and A(i) at the current data point.