SIGNAL PROCESSING APPARATUS

• US 20130345523A1
• Filed: 06/10/2013
• Published: 12/26/2013
• Est. Priority Date: 10/07/1994
• Status: Abandoned Application

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Diab, Mohamed K., Kiani-Azarbayjany, Esmaiel, Elfadel, Ibrahim M., McCarthy, Rex J., Weber, Walter M., Smith, Robert A.
• Application Number:
  US13/914,276
• Publication Number:
  US 20130345523A1
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02154 by optical transmission
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence
• 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 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7253 characterised by using transforms
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 6/00 Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment instruments measuring radiation intensity for application in the field of nuclear medicine, e.g. in vivo counting, G01T1/161; apparatus for taking X-ray photographs G03B42/02
• CPC Class Codes: A61B 8/00 Diagnosis using ultrasonic, sonic or infrasonic waves imaging of objects using sonar G01S15/00
• CPC Class Codes: A61B 8/5276 : due to motion
• 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

The present invention involves a method and an apparatus for analyzing measured signals, including the determination of a measurement of oxygen saturation and respiration rate in the measured signals during a calculation of a physiological parameter of a monitored patient. Use of this invention is described in particular detail with respect to oximetry-based measurements but extends to other types of measurements.

Claims

1. A patient monitoring system configured to determine one or more physiological characteristics of a patient, the system comprising:

a plurality of light emitters configured to emit light of at least two different wavelengths into tissue of a patient;

a detector configured to detect the emitted light after attenuation by the tissue and output a signal indicative of the detected light; and

a processing system configured to receive and process the detected light and determine information indicative of oxygen saturation, pulse rate and respiration rate, the processing system configured to reduce an effect of motion noise by using at least a frequency domain calculation.

2. The patient monitoring system of claim 1, wherein the frequency domain calculation comprises a Fourier transform.

3. The patient monitoring system of claim 1, wherein the processing system is further configured to determining a plurality of ratios of values based on the at least two different wavelengths.

4. The patient monitoring system of claim 1, wherein the processing system is further configured to use at least a wavelet transform in the determination of at least a portion of the information.

5. The patient monitoring system of claim 1, wherein the information comprises a primary signal and a reference signal, the primary signal indicative of the oxygen saturation and the reference signal indicative of the respiration rate.

6. A patient monitor configured to determine one or more physiological characteristics of a patient, the system comprising:

an input for receiving from a detector an indication of light of first and second wavelengths attenuated by body tissue carrying pulsing blood over a period of time;

a processor configured to receive and process the detected light and determine information indicative of oxygen saturation, pulse rate and respiration rate, the processing system configured determine at least a portion of the information using at least a frequency domain calculation.

7. The patient monitor of claim 6, wherein the frequency domain calculation comprises a Fourier transform.

8. The patient monitor of claim 6, wherein the processing system is further configured to determining a plurality of ratios of values based on the at least two different wavelengths.

9. The patient monitor of claim 6, wherein the processing system is further configured to use at least a wavelet transform in the determination of at least a portion of the information.

10. The patient monitor of claim 6, wherein the information comprises a primary signal and a reference signal, the primary signal indicative of the oxygen saturation and the reference signal indicative of the respiration rate.

11. A method of determining a physiological parameter of a patient comprising:

supplying a control signal to alternately generate a light signal of at least a first wavelength and a second wavelength and at a modulation frequency higher than a rate of a physiological parameter of interest;

receiving an attenuated signal based on the light signal, the attenuated signal comprising a first component representing an ambient light signal and a second component representing the light signal of the first or second wavelength;

digitizing the attenuated signal to generate a digital signal;

processing the digital signal to generate a processed signal, said processing comprising transforming the digitized signal to the frequency domain and determining a physiological parameter of interest, the physiological parameter being a respiration rate.

12. The method of claim 11, wherein transforming the digitized signal to the frequency domain comprises using a Fourier transform.

13. The method of claim 11, further comprising using at least a wavelet transform to determine the parameter of interest.

14. The method of claim 11, further comprises determining a primary signal and a reference signal, the primary signal indicative of the oxygen saturation and the reference signal indicative of the respiration rate.