Multi-wavelength physiological monitor

• US 20060009688A1
• Filed: 05/27/2005
• Published: 01/12/2006
• Est. Priority Date: 07/07/2004
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Laboratories, Inc. (Masimo Corporation)
• Inventors: Weber, Walter M., Al-Ali, Ammar, Diab, Mohamed, Lamego, Marcelo M., Kiani, Joe
• Granted Patent: US 7,343,186 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• 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 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• 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 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/72 Signal processing specially adapted for physiological signals or for diagnostic purposes character recognition, recognising digital ink, document-oriented image-based pattern recognition G06V30/00; recognition or understanding of postal images G06V30/424
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 2201/0627 Use of several LED's for spectral resolution
• CPC Class Codes: G01N 2201/129 Using chemometrical methods

Abstract

A physiological monitor for determining blood oxygen saturation of a medical patient includes a sensor, a signal processor and a display. The sensor includes at least three light emitting diodes. Each light emitting diode is adapted to emit light of a different wavelength. The sensor also includes a detector, where the detector is adapted to receive light from the three light emitting diodes after being attenuated by tissue. The detector generates an output signal based at least in part upon the received light. The signal processor determines blood oxygen saturation based at least upon the output signal, and the display provides an indication of the blood oxygen saturation.

Claims

1. A physiological monitor for determining blood oxygen saturation of a medical patient, comprising:

a sensor, wherein said sensor comprises at least three light emitting diodes, each light emitting diode adapted to emit light of a different wavelength and a detector, wherein said detector is adapted to receive light from said at least three light emitting diodes after being attenuated by tissue, and wherein said detector generates an output signal based at least in part upon said received light;

a signal processor, wherein said signal processor determines blood oxygen saturation based at least upon said output signal; and

a display, wherein said display provides an indication of said blood oxygen saturation.

2. The physiological monitor of claim 1, wherein said at least three light emitting diodes comprise eight light emitting diodes.

3. The physiological monitor of claim 1, wherein said different wavelength comprises about 640 nm.

4. The physiological monitor of claim 1, wherein said different wavelength comprises about 950 nm.

5. The physiological monitor of claim 1, wherein said signal processor comprises a multi-variate process estimator.

6. The physiological monitor of claim 5, wherein said multi-variate process estimator comprises a pseudo-inverse.

7. A sensor module for providing a composite signal to a multi-wavelength physiological monitor, said sensor comprising:

at least three light emitting diode, each light emitting diode adapted to emit light of a different wavelength; and

a detector, wherein said detector is adapted to receive light from said at least three light emitting diodes after being attenuated by tissue, and wherein said detector generates an output signal based at least in part upon said received light.

8. The sensor module of claim 7, wherein said at least three light emitting diodes comprise eight light emitting diodes.

9. The physiological monitor of claim 7, wherein said different wavelength comprises about 640 nm.

10. The physiological monitor of claim 7, wherein said different wavelength comprises about 950 nm.

11. A physiological monitor for determining blood oxygen saturation of a medical patient, comprising:

a signal processor, wherein said signal processor is adapted to receive a composite signal indicative of attenuation of at least three wavelengths of light by tissue, and wherein said signal processor is adapted to determine blood oxygen saturation based at least upon said composite signal; and

a display, wherein said display provides an indication of blood oxygen saturation.

12. The physiological monitor of claim 11, wherein said at least three wavelengths comprise eight wavelengths.

13. The physiological monitor of claim 11, wherein said at least three wavelengths comprise about 640 nm.

14. The physiological monitor of claim 11, wherein said at least three wavelengths comprise about 950 nm.

15. The physiological monitor of claim 11, wherein said signal processor comprises a multi-variate process estimator.

16. The physiological monitor of claim 15, wherein said multi-variate process estimator comprises a psuedo-inverse.

17. A method of determing the blood oxygen saturation of a patient, comprising:

receiving at least three attenuated light signals that have been attenuated by tissue;

generating a composite signal based at least in part on said at least three attenuated light signals;

demodulating and sub-sampling said composite signal to yield a data signal;

performing statistical operations on said data signal to yield at least one statistical output signal;

performing a saturation transform on said data signal to deterimine a saturation transform output signal; and

calculating blood oxygen saturation based at least in part on said at least one statistical output signal and said saturation transform output signal.

18. A method of determing the blood oxygen saturation of a patient, comprising:

receiving at least three data signals indicative of at least three wavelengths of light that have been attenuated by tissue;

determining at least three output signals based upon said three data signals, wherein said determining at least three output signals comprises determining an RMS value of each corresponding said at least three data signals;

determining a reference signal based at least in part on said at least three output signals and a scan signal, wherein said determining a reference signal comprises processing said at least three outputs signals and said scan signal with a reference generator;

selecting a selected signal from at least one of sad at least three outputs signals;

processing said selected signal and said reference signal with a multi-variate process estimator to determine a process estimator output; and

determining blood oxygen saturation based at least in part on said process estimator output.

19. The method of claim 18, wherein said reference generator comprises a lookup table.

20. The method of claim 18, wherein said reference generator comprises a polynomial.

21. The method of claim 18, wherein said multi-variate process estimator comprises a pseudo-inverse.