| 摘要 |
The invention relates inter alia to a method for measuring the oxygen saturation of the blood flowing in a peripheral human or animal body part (20), in which electromagnetic radiation (q1′(t), q2′(t)) having a first and a second wavelength is irradiated into the peripheral body part or irradiated through the peripheral body part, the reflected or transmitted radiation (x1′(t), x2′(t)) is measured to form two measurement signals (x1(t), x2(t)), and the oxygen saturation of the blood is determined by evaluating the two measurement signals. According to the invention, provision is made for a mathematical mixing model to be used to evaluate the two measurement signals and a statistical evaluation method to be applied to the two measurement signals, wherein, as a boundary condition, the statistical independence of a useful source signal and an interference source signal is assumed and the useful source signal and the two useful-signal-related filter functions are determined with the aid of the evaluation method and the oxygen saturation of the blood is determined using the three aforementioned signals. |
| 主权项 |
1. A method for measuring the oxygen saturation of the blood flowing in a peripheral human or animal body part, in which electromagnetic radiation (q1′(t), q2′(t)) having a first wavelength and a second wavelength is irradiated into the peripheral body part or irradiated through the peripheral body part, reflected or transmitted radiation (x1′(t), x2′(t)) corresponding to the first wavelength and the second wavelength is measured to form two measurement signals (x1(t), x2(t)), and the oxygen saturation of the blood is determined by evaluating the two measurement signals, comprising:
evaluating the two measurement signals with a mathematical mixing model, in which a useful-signal-related filter function related to the first wavelength, an interference-signal-related filter function related to the first wavelength, a useful-signal-related filter function related to the second wavelength, an interference-signal-related filter function related to the second wavelength, a useful source signal contained in the measurement signals and an interference source signal contained in the measurement signals are used in the evaluation, applying a statistical evaluation method to the two measurement signals, wherein, as a boundary condition, the statistical independence of the useful source signal and the interference source signal is assumed and determining therefrom the useful source signal and the two useful-signal-related filter functions, and determining the oxygen saturation of the blood using the three signals determined with the statistical evaluation, wherein the mathematical mixing model is a convolutive mixing model where the two measurement signals emerge from a superposition of filtered source signals which are filtered by mixing filters, wherein the following mathematical mixing model is used in evaluating the two measurement signals:
x1(t)=h11(t)*s1(t)+h12(t)*s2(t)x2(t)=h21(t)*s1(t)+h22(t)*s2(t) wherein h11(t) denotes the useful-signal-related filter function related to the first wavelength, h12(t) denotes the interference-signal-related filter function related to the first wavelength, h21(t) denotes the useful-signal-related filter function related to the second wavelength, h22(t) denotes the interference-signal-related filter function related to the second wavelength, s1(t) denotes the useful source signal contained in the measurement signal, s2(t) denotes the interference source signal contained in the measurement signal, x1 (t) denotes the measurement signal at the first wavelength and x2(t) denotes the measurement signal at the second wavelength. |
