PULSE PHOTOMETER

• US 20150272488A1
• Filed: 03/19/2015
• Published: 10/01/2015
• Est. Priority Date: 03/28/2014
• Status: Active Grant

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: UKAWA, Teiji, ITO, Kazumasa, UEDA, Yoshinori, FUJISAKI, Hideki
• Granted Patent: US 9,854,999 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 5/7214 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 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7405 using sound
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7455 characterised by tactile indication, e.g. vibration or electrical stimulation
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 2201/061 Sources
• CPC Class Codes: G01N 2201/12 Circuits of general importance; Signal processing
• CPC Class Codes: G01N 33/4925 measuring blood gas content, e.g. O2, CO2 , HCO3

Abstract

A pulse photometer includes a light emitter, a light detector, a first signal separator that separates a first signal component and a first noise component, a second signal separator that separates a second signal component and a second noise component, a first determining section, a second determining section, and a concentration calculating section that calculates a concentration of a light absorption material in blood of the subject based on a fundamental frequency of the first signal component or a fundamental frequency of the second signal component.

Claims

1. A pulse photometer comprising:

an emitter that emits at least three kinds of light beams at different wavelengths;

a detector that outputs at least three kinds of intensity signals in accordance with intensities of the at least three kinds of light beams that are transmitted through or reflected from a living tissue of a subject;

a first signal separator that separates a first signal component and a first noise component based on intensity signals of two kinds of light beams in a first combination selected from the at least three kinds of light beams;

a second signal separator that separates a second signal component and a second noise component based on intensity signals of two kinds of light beams in a second combination selected from the at least three kinds of light beams;

a first determining section that determines whether a first difference between a first signal absorbance ratio of the first signal component and a first noise absorbance ratio of the first noise component is smaller than a first predetermined value or not;

a second determining section that, when it is determined that the first difference is smaller than the first predetermined value, determines whether a second difference between a second signal absorbance ratio of the second signal component and a second noise absorbance ratio of the second noise component is smaller than a second predetermined value or not; and

a concentration calculating section that, when it is determined that the first difference is equal to or larger than the first predetermined value, calculates a concentration of a light absorption material in blood of the subject based on a fundamental frequency of the first signal component, and, when it is determined that the second difference is equal to or larger than the second predetermined value, calculates the concentration of the light absorption material in blood based on a fundamental frequency of the second signal component.

2. The pulse photometer according to claim 1, wherein each of the first combination and the second combination includes an infrared red light beam and a red light beam as the two kinds of light beams.

3. The pulse photometer according to claim 1, wherein the pulse photometer further includes a notifying section which, if it is determined that the second difference is smaller than the second predetermined value, notifies of an error state.

4. The pulse photometer according to claim 1, wherein the wavelengths of the at least three kinds of light beams are 660 nm, 700 nm, and 880 nm.

5. The pulse photometer according to claim 4, wherein the at least three kinds of light beams include four kinds of light beams at wavelengths are 660 nm, 700 nm, 730 nm, and 880 nm.

6. The pulse photometer according to claim 4, wherein the at least three kinds of light beams include four kinds of light beams at wavelengths are 660 nm, 700 nm, 880 nm, and 940 nm,