SIGNAL PROCESSING APPARATUS

• US 20110245654A1
• Filed: 06/13/2011
• Published: 10/06/2011
• Est. Priority Date: 03/07/1991
• Status: Abandoned Application

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Weber, Walter M., Diab, Mohamed K., Kiani-Azarbayjany, Esmaiel
• Application Number:
  US13/159,341
• Publication Number:
  US 20110245654A1
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: G06F 2218/04 Denoising
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H

Abstract

A signal processor which acquires a first signal, including a first primary signal portion and a first secondary signal portion, and a second signal, including a second primary signal portion and a second secondary signal portion, wherein the first and second primary signal portions are correlated. The signals may be acquired by propagating energy through a medium and measuring an attenuated signal after transmission or reflection. Alternatively, the signals may be acquired by measuring energy generated by the medium. A processor of the present invention generates a primary or secondary reference signal which is a combination, respectively, of only the primary or secondary signal portions. The secondary reference signal is then used to remove the secondary portion of each of the first and second measured signals via a correlation canceler, such as an adaptive noise canceler, preferably of the joint process estimator type. The primary reference signal is used to remove the primary portion of each of the first and second measured signals via a correlation canceler. The processor of the present invention may be employed in conjunction with a correlation canceler in physiological monitors wherein the known properties of energy attenuation through a medium are used to determine physiological characteristics of the medium. Many physiological conditions, such as the pulse, or blood pressure of a patient or the concentration of a constituent in a medium, can be determined from the primary or secondary portions of the signal after other signal portion is removed.

Claims

1. A method determining a value of a physiological parameter, the method comprising:

receiving three or more intensity signals from at least one light-sensitive detector which detects light attenuated by body tissue carrying pulsing blood, wherein the three or more intensity signals correspond to detection of at least three wavelengths of the light; and

determining a value of at least on physiological parameter using the three or more intensity signals, wherein the three or more intensity signals include motion induced noise.

2. A method of reducing an effect of motion induced noise on a plurality of intensity signals during the determination of a parameter of pulsing blood, the method comprising:

receiving a plurality of intensity signals from at least one light-sensitive detector which detects light of a plurality of wavelengths attenuated by body tissue carrying pulsing blood; and

processing one of the plurality of intensity signals using data from an additional intensity signal other than the plurality of intensity signals, the additional intensity signal corresponding to an additional wavelength of light, wherein the processing determines a value of a physiological parameter in pulsing blood during motion induced noise, wherein the data from the extra wavelength is used to reduce an effect of the motion induced noise.

3. A physiological monitor for determining a physiological parameter of a patient, the physiological monitor comprising:

an input which receives three or more intensity signals from at least one light-sensitive detector which detects light attenuated by body tissue carrying pulsing blood, wherein the three or more intensity signals correspond to detection of at least three wavelengths of the light; and

a processor which determines a value of a physiological parameter using the three or more intensity signals, wherein the three or more intensity signals include motion induced noise.