Condensed oximeter system and method with noise reduction software
First Claim
1. A method for determining a parameter of blood, comprising the steps of:
- transmitting first and second wavelengths of electromagnetic energy toward a tissue sample;
detecting the first and second wavelengths of electromagnetic energy scattered by the tissue sample, thereby generating first and second analog signals corresponding to the first and second wavelengths, the first and second analog signals each having an AC and a DC component;
separating the AC components of the first and second analog signals from the first and second analog signals to produce first and second separated AC components;
computing the derivatives of the first and second separated AC components;
taking a linear regression of a ratio of the derivatives of the separated AC components of the first and second analog signals for a plurality of sample points in a period; and
computing the parameter of blood, the parameter of blood corresponding to the derivatives of the first and second separated AC components.
0 Assignments
0 Petitions
Accused Products
Abstract
A compact pulse oximetry system and method which separates the combined signal into its respective AC and DC components. By separating the signal into AC and DC components, a smaller order bit A/D converter may be used while still maintaining signal accuracy. Instead of using the combined signal to calculate the oxygen saturation content, the system microprocessor computes the Ratio of Ratios using the derivative of the separated AC component of the diffused signal to calculate the oxygen saturation of the measured fluid. To calculate the Ratio of Ratios, a ratio of the derivative value of the separated AC component is used. Instead of taking a single sample between the peak and valley of the signal, the oximeter system samples each value. To decrease the effect of system noise, a linear regression is performed over each sample.
-
Citations
34 Claims
-
1. A method for determining a parameter of blood, comprising the steps of:
-
transmitting first and second wavelengths of electromagnetic energy toward a tissue sample; detecting the first and second wavelengths of electromagnetic energy scattered by the tissue sample, thereby generating first and second analog signals corresponding to the first and second wavelengths, the first and second analog signals each having an AC and a DC component; separating the AC components of the first and second analog signals from the first and second analog signals to produce first and second separated AC components; computing the derivatives of the first and second separated AC components; taking a linear regression of a ratio of the derivatives of the separated AC components of the first and second analog signals for a plurality of sample points in a period; and computing the parameter of blood, the parameter of blood corresponding to the derivatives of the first and second separated AC components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. An apparatus for measuring a parameter of the blood, comprising:
-
at least two emitting means for emitting first and second wavelengths of electromagnetic energy toward a tissue sample; means responsive to the emitting means for detecting the first and second wavelengths of electromagnetic energy scattered by the tissue sample, the detection means producing first and second analog signals, each of said first and second analog signals having an AC and a DC component, the first analog signal corresponding to the first wavelength of electromagnetic energy and the second analog signal corresponding to the second wavelength of electromagnetic energy; means for separating the AC component of the first analog signal from the first analog signal to produce a first separated AC component and separating the AC component of the second analog signal from the second analog signal to produce a second separated AC component, wherein the means for separating includes a subtractor circuit; an analog to digital converter coupled to the means for separating, the analog to digital converter converting the first separated AC component into a first digital signal and the second separated AC component into a second digital signal, the analog to digital converter having an input voltage range; means for taking a linear regression of a ratio of derivatives of the first and second separated AC components for a plurality of sample points in a period, the means for taking a linear regression including a microprocessor which computes the parameter of blood from the first and second digital signals, wherein the value of the parameter of blood corresponds to the derivative of the first separated AC component and the derivative of the second separated AC component; and means for sensing an impedance corresponding to the at least one wavelength of electromagnetic energy.
-
-
16. A method for determining a parameter of blood, comprising the steps of:
-
transmitting at least one wavelength of electromagnetic energy through a sample; detecting the at least one wavelength of electromagnetic energy through the sample; generating at least one analog signal corresponding to the detected at least one wavelength, the at least one analog signal having an AC and a DC component; separating the AC component of the at least one analog signal from the at least one analog signal to produce a separated AC component; computing the derivative of the separated AC component; and computing the parameter of blood using the derivative of the separated AC component. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
-
-
31. A method for determining a parameter of blood, comprising the steps of:
-
transmitting at least one wavelength of electromagnetic energy through a sample; detecting the at least one wavelength of electromagnetic energy through the sample; generating at least one analog signal corresponding to the detected at least one wavelength; computing the derivative of the analog signal; and computing the parameter of blood using the derivative of the analog signal.
-
-
32. A method for determining a parameter of blood, comprising the steps of:
-
transmitting first and second wavelengths of electromagnetic energy toward a tissue sample; detecting the first and second wavelengths of electromagnetic energy scattered by the tissue sample, thereby generating first and second analog signals corresponding to the first and second wavelengths, the first and second analog signals each having an AC and a DC component; computing the derivatives of the first an d second analog signals; taking a linear regression of a ratio of the derivatives of the first and second analog signals for a plurality of sample points in a period; and computing the parameter of blood, the parameter of blood corresponding to the derivatives of the analog signals. - View Dependent Claims (33)
-
-
34. An apparatus for measuring a parameter of the blood, comprising:
-
at least two emitting means for emitting first and second wavelengths of electromagnetic energy toward a tissue sample; means responsive to the emitting means for detecting the first and second wavelengths of electromagnetic energy scattered by the tissue sample, the detection means producing first and second analog signals, each of said first and second analog signals having an AC and a DC component, the first analog signal corresponding to the first wavelength of electromagnetic energy and the second analog signal corresponding to the second wavelength of electromagnetic energy; an analog to digital converter coupled to the means for separating, the analog to digital converter converting the first analog signal into a first digital signal and the second analog signal into a second digital signal; and means for taking a linear regression of a ratio of derivatives of the first and second analog signal for a plurality of sample points in a period, the means for taking a linear regression including a microprocessor which computes the parameter of blood from the first and second digital signals, wherein the value of the parameter of blood corresponds to the derivative of the first analog signal and the derivative of the second analog signal.
-
Specification