Method and apparatus for estimating physiological parameters using model-based adaptive filtering
First Claim
1. A method for generating a pulse rate of a patient using data corresponding to at least one wavelength of electromagnetic energy transmitted through tissue of the patient, the method comprising:
- defining a comb filter to isolate signal energy in the data corresponding to a fundamental frequency and related higher frequency components;
determining a particular frequency that optimized energy at an output of the comb filter; and
generating a filtered pulse rate corresponding to the particular frequency.
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Abstract
A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment. The filters adaptively modify a set of averaging weights to optimally estimate the physiological parameters.
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Citations
37 Claims
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1. A method for generating a pulse rate of a patient using data corresponding to at least one wavelength of electromagnetic energy transmitted through tissue of the patient, the method comprising:
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defining a comb filter to isolate signal energy in the data corresponding to a fundamental frequency and related higher frequency components; determining a particular frequency that optimized energy at an output of the comb filter; and generating a filtered pulse rate corresponding to the particular frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for generating a pulse rate of a patient using data corresponding to at least one wavelength of electromagnetic energy transmitted through tissue of the patient comprising:
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means for defining a comb filter to isolate signal energy in the data corresponding to a fundamental frequency and related higher frequency components; means for determining a particular frequency that optimizes energy at an output of the comb filter; and means for generating a filtered pulse rate corresponding to the particular frequency. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A circuit for generating a pulse rate of a patient using data corresponding to at least one wavelength of electromagnetic energy transmitted through tissue of the patient comprising:
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a comb filter operative to isolate signal energy in the data corresponding to a fundamental frequency and related higher frequency components; a processor coupled to the comb filter and operative to determine a particular frequency that optimizes energy at an output of the comb filter; and an averaging filter coupled to the processor and operative to generate a filtered pulse rate corresponding to the particular frequency. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification