Nihon Kohden Corporation

Other

Takuo Aoyagi

Masayoshi Fuse

Michio Kanemoto

Naoki Kobayashi

Teiji Ukawa

Cheng-tai Xie

Cheng Tai Xie

Sunao Takeda

Tadashi Sasaki

Nobutaka Kobayashi

Masayuki Kato

Hideaki Hirahara

Yoshiaki Shindo

Katsuyuki Miyasaka

Chen-tai Xie

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

Using the principle of pulse oximetry, the relationship between the logarithm of dye density and the passage of time is obtained to determine a regression line for the linear portion of the relationship; an intial dye density in the blood is determined for the point of time that defines the mean transit time for the initial circulation of the injected dye on the regression line; and the circulating blood volume is calculated from the thus determined initial dye density.

Apparatus for measuring circulating blood volume

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

Intensities of light of two different wavelengths transmitted through a tissue of a living body are measured during a first time period. A data processor determines a first regression line using logarithmically processed data corresponding to the light intensities measured during the first time period. An operator injects a dye into the living body and measurements of intensities of light at the two different wavelengths are made during a later time period. The data processor determines a second regression line using logarithmically processed data corresponding to the light intensities measured during the later time period. The data processor finds an intersection of the two regression lines and uses the intersection to determine a bloodless level point. The processor then forms a dye dilution curve incorporating the bloodless level point data.

Apparatus and method for measuring oxygen saturation in blood and

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

Disclosed is an apparatus for measuring a predetermined data of a living tissue, such as an oxygen saturation, a dye dilution curve and level of hemoglobin. The apparatus has an illumination intensity computing and storing circuit that stores the intensities of light components emitted from a three-wavelength light source assembly, and a computing circuit that calculates the intensity ratios of illuminating light from the intensity data stored in the circuit. The circuit determines the predetermined data of blood on the basis of the calculated intensity ratios and the intensities of light transmitted through a living tissue under assay, and it displays the predetermined data on display unit. The apparatus is capable of measuring the predetermined data without relying upon pulsations that occur in the subject.

Apparatus for measuring predetermined data of living tissue

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

An apparatus for measuring the change in the concentration of a pigment in blood is disclosed which comprises: light quantity detecting units for continuously detecting the quantities of radiations of light having different wavelengths that have been transmitted or reflected by living tissue containing pulsating blood; first computing unit which, when the concentration or absorptivity coefficient of a light-absorbing component in the blood changes with respect to light having either one of said wavelengths, computes the quantities of radiations of transmitted or reflected light having the wavelengths when the living tissue is in a state of ischemia on the basis of the constant and pulsating components of the quantity of each radiation of light that has been detected by the light quantity detectors both before and after the change occurred; and second computing unit which continuously determines the concentration of a pigment of interest in the blood by performing calculations based on the results of computation by the first computing means and on the quantities of radiations of light detected by the light quantity detecting units.

Growing community of inventors

Tokyo, Japan

Takuo Aoyagi