PULSE OXIMETRY AND PULSE OXIMETER

• US 20090318787A1
• Filed: 06/18/2009
• Published: 12/24/2009
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: AOYAGI, Takuo, KANEMOTO, Michio, FUSE, Masayoshi, UKAWA, Teiji
• Granted Patent: US 8,548,546 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts

Abstract

A pulse oximetry includes: irradiating living tissue with a plurality of light beams of different wavelengths; receiving the light beams transmitted through or reflected from the living tissue and converting the received light beams to electric signals which correspond to the different wavelengths; time-segmenting time series data of the electric signals; calculating, with respect to each of the segmented time series data of the electric signals, a slope value of a regression line between each two of the electric signals; calculating SaO2 based on the slope value of each of the segmented time series data of the electric signals; constructing a histogram of SaO2 for each predetermined number of time segments; and obtaining a mode value from the histogram as SpO2 to be output of the pulse oximetry.

Claims

1. A pulse oximetry comprising:

irradiating living tissue with a plurality of light beams of different wavelengths;

receiving the light beams transmitted through or reflected from the living tissue and converting the received light beams to electric signals which correspond to the different wavelengths;

time-segmenting time series data of the electric signals;

calculating, with respect to each of the segmented time series data of the electric signals, a slope value of a regression line between each two of the electric signals;

calculating SaO2 based on the slope values of each of the segmented time series data of the electric signals;

constructing a histogram of SaO2 for each predetermined number of time segments; and

obtaining a mode value from the histogram as SpO2 to be output of the pulse oximetry.

2. The pulse oximetry according to claim 1, wherein

the time series data of the electric signals are passed through a filter to block a low-frequency component, before time-segmenting the time series data of the electric signals.

3. The pulse oximetry according to claim 1, further comprising:

calculating, with respect to each of the segmented time series data of the electric signals, correlation between each two of the electric signals,

wherein, when the correlation is less than a predetermined value, the slope value which corresponds to the correlation is deleted.

4. The pulse oximetry according to claim 1, wherein a smoothing process is applied to the histogram of the SaO2, before obtaining the mode value.

5. A pulse oximeter comprising:

a light emitter, which irradiates living tissue with a plurality of light beams of different wavelengths;

a light receiver, which receives the light beams transmitted through or reflected from the living tissue and which converts the received light beams to electric signals which correspond to the different wavelengths;

a processor, which segments time series data of the electric signals;

a slope value calculator, which calculates, with respect to each of the segmented time series data of the electric signals, a slope value of a regression line between each two of the electric signals;

an SaO2 calculator, which calculates SaO2 based on the slope values of each of the segmented time series data of the electric signals;

a histogram constructer, which constructs a histogram of SaO2 for each predetermined number of time segments; and

an obtainer, which obtains a mode value from the histogram as SpO2 to be output of the pulse oximeter.