Nihon Kohden Corporation

Masayoshi Fuse

Takuo Aoyagi

Michio Kanemoto

Naoki Kobayashi

Cheng-tai Xie

Teiji Ukawa

Cheng Tai Xie

Sunao Takeda

Masayuki Kato

Hideaki Hirahara

Yoshiaki Shindo

Chen-tai Xie

Akio Yamada

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.

Pulse oximetry and pulse oximeter

To measure oxygen saturation in blood, living tissue is irradiated with a first light beam having a first wavelength and a second light beam having a second wavelength. A first electrical signal is generated from the first light beam reflected from or transmitted through the tissue. A second electrical signal is generated from the second light beam reflected from or transmitted through the tissue. The first electrical signal is divided into a plurality of first segments, each including a part of the first electrical signal for a predetermined time period. The second electrical signal is divided into a plurality of second segments, each including a part of the second electrical signal for the predetermined time period. A gradient of a regression line is calculated between every one of the first segments and an associated one of the second segments, thereby obtaining a plurality of gradients.

Time-segmented pulse oximetry and pulse oximeter performing the same

In a pulse oximeter for obtaining an oxygen saturation in a blood, a light emitter irradiates a living tissue with light beams having five different wavelengths. A light receiver receives respective light beams reflected from or transmitted through the living tissue, and converts the received light beams to electric signals. A first calculator calculates five attenuation changes of the living tissue based on fluctuations of the respective electric signals. A second calculator calculates at least four attenuation change ratios from the five attenuation changes. Each of the attenuation change ratios is defined by a ratio between any two of the five attenuation changes. A third calculator calculates the oxygen saturation based on the attenuation change ratios, while taking an oxygen saturation of arterial blood, an oxygen saturation of venous blood, a ratio between changes in arterial blood and venous blood, and a tissue term as four unknown values.

Pulse oximeter

A probe includes a light irradiating device and a light receiving device , which are oppositely disposed sandwiching living tissue . The light irradiating device includes a light source and a scattering plate located in front of the light source . The light receiving device includes a photo diode and a light scattering portion. With such an arrangement, of the attenuation of the living tissue , non-absorbing attenuation is free from the wavelength. A ratio of absorbing attenuation and a thickness of a blood layer is not affected by a thickness of living tissue. Further, the absorbing attenuation is not dependent on a depth of the blood layer.

Probe and apparatus for determining concentration of light-absorbing materials in living tissue

Irradiating device,of a pulse oximeter includes a scattering plate,Scattering light is projected into a living tissue. The diameter of the incident area is sufficiently large compared with that of a light receiving area or vice versa. Therefore, tissue terms in a theoretical formula of &PHgr; which represents a ratio of changes of optical densities of tissue measured with two wavelengths are not dependent on the wavelength. The digital processor,calculates an oxygen saturation by substituting &PHgr; measured into simultaneous equations.

Apparatus for determining concentrations of light-absorbing materials in living tissue

Light beams of different wavelengths, emitted from a light generating device, are transmitted through a living tissue. The transmitted light beams are converted into electrical signals by a photoelectric transducing device. A pulsation calculating device calculates a pulsation of an absorbance of tissue of a living tissue for each wavelength on the basis of the output signal of the photoelectric transducing device. By using this, a pulsation ratio calculating device calculates the ratio of the pulsations of the absorbance values. A concentration calculating device puts the output signal of the pulsation ratio calculating device into a formula having a single unknown on the tissue term, which is constructed on the basis of the fact that a predetermined relation is present between the tissue terms of the respective wavelengths, thereby calculating a value of the tissue term and the concentration of light absorbing material in blood.

Apparatus for determining the concentration of light-absorbing materials

Light of various wavelengths emitted from light sources and transmitted through vital tissues is converted by light sensors and current/voltage transducers, into electric signals. The signals are converted into digital values by an A/D converter. The light source emits light of a wavelength which can be optically absorbed by water. A computer obtains a ratio of variations of the digital values for each wavelength, and calculates the values of tissue terms and the hemoglobin concentration on the basis of the ratios. In the calculation, since tissue terms of the wavelengths have mutual constant relationships, an equation which is prepared so that there exists only one unknown in the tissue terms is used.

Apparatus for measuring hemoglobin

A supporting shaft stands on an external auditory canal arm holding an LED. An attaching portion holding a PD is rotatably connected to one end of a holding arm. A column having a through hole 11b into which the supporting shaft is slidably inserted is fixed to the other end of the holding arm. The external auditory canal arm and the holding arm are connected to each other by a coil spring.

Tissue transmitted light sensor

An external auditory canal arm having a photo sensing element at the distal end thereof is inserted into an external auditory meatus. A contact piece 1b having a light emitting element is set to a location near an ear lobe on the surface of a skin of the temporal region of a subject. Light that is emitted from the light emitting element and transmitted through the superficial temporal artery region, is received by the photo sensing element. A variation of the quantity of light when passing through blood flowing through the superficial temporal artery, which is caused by light absorptive materials in the blood, is detected, to thereby obtain oxygen saturation, cardiac output and blood volumes, and the like in the blood.

Method of measuring the quantity of attenuation of light transmitted

A photo-electric pulse measuring probe includes a pair of supporting members which have a light emitting element and a light receiving element adjacent first end portions thereof, respectively, in such a manner that the light emitting element and the light receiving elements are confronted with each other, and which are swingably coupled to each other at the other end portions thereof. The light emitting element and the light receiving element are covered with elastic members, respectively, and wavy surfaces are formed in the mating surfaces of the elastic members, respectively, so that a user's finger is supported by a number of points during measurement.

Photo-electric pulse wave measuring probe

An apparatus for calibrating a pulse oximeter which can improve the repetitivity of measured values for calibration tests and which can calibrate the pulse oximeter with a high reliability. A tissue model having a light-absorbing characteristic approximated to that of the tissue of a living body is inserted into a space between a light-emitting section and a light-receiving section of a measuring probe that is connected to the pulse oximeter, and a blood model having a light-absorbing characteristic that is approximated to that of the blood is moved within the tissue model so as to enter into or exit from the space between the light-emitting section and the light-receiving section.

Apparatus for calibrating pulse oximeter

A monitoring device for preventing urinary incontinence has the following components: a high-frequency constant-current power supply adapted to supply a pair of terminals which are set on the surface of a human body across the urinary bladder; a high-frequency voltage signal detecting means which conducts wave detection from a high-frequency voltage signal sensed by a pair of sensing electrodes which are set on the human body surface at positions on the path of the high-frequency electrical current flowing between the pair of terminals; a DC component detecting means 13 which detects the DC component of the signal detected by the high-frequency voltage signal detecting means; a variance component detecting means for detecting variance component of the signal detected by the high-frequency voltage signal detecting means; a variance-to-DC ratio computing means for computing the ratio between the DC component and the variance component; and a variance-to-DC ratio evaluating means for activating an informing means when the computed value of the variance-to-DC ratio has reached a predetermined threshold level.

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Tokyo, Japan

Masayoshi Fuse