JPH05504266A - oximeter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] oximeter [Technical field] The present invention relates to an oximeter, which is a device for measuring oxygen saturation of blood.

[Background technology] Such devices are of great value to doctors as they indicate the degree of oxygenation of a patient's blood. be. Traditional equipment, while essentially useful, makes it difficult to interpret the results of measurement techniques. It has its drawbacks due to the many errors that are likely to be made in doing so.

Many conventional devices, commonly known as pulse oximeters, have two or using irradiation at longer wavelengths; one is red-headed (650-750 nm The other is in the infrared region (750 nanometers or more). detection The measured transmitted or reflected intensity is calculated based on the Beer-Lambert transmittance law. and compare them to estimate oxygen saturation. Such comparative measurements are described below. Errors tend to occur for various reasons. 1. Due to the optical properties of the skin over time. change.

2. Beer's law does not always apply.

3. Various unknown blood components present in the optical path.

4. Unexpected mixing of arterial and venous blood in the optical path.

5. Poor peripheral circulation.

6. Influence of many variations.

7. Abnormal blood pH 8. Postbiotics due to movement.

9. Non-monochromaticity and stability of (LED) light sources.

10. Error in oxygen pressure drop.

11-1 Sites are limited.

12. Ambient light and infrared illumination.

13. Fetal hemoglobin, metahemoglobin, carboxyhemoglobin, etc. Hemoglobin derivative.

Acceptable corrections are possible for these sources of error, but such corrections are costly. and increase the complexity of the equipment, which has an adverse effect on the usefulness of the measurement as a whole. .

Furthermore, various special proposals have been made to measure hemoglobin concentration. Ta. Reeves, Re5piration Physiology, Vo l, 42. No. 3 December 1980 iNethe rlands/Elsevier) pp, 299-315. A cell containing a film and oxygen pressure control around the blood film is used. Conventional method using two different wavelengths, but instead of using the usual red and infrared wavelengths. Then, two Sore measurements are carried out.DE-A-3615973 Distinguish whether syhemoglobin or deoxyhemoglobin was present Disclosed is a method for measuring hemoglobin concentration without any hemoglobin concentration. With enough oxygen, Converts as much hemoglobin as possible to oxyhemoglobin and converts this converted substance into Measurements are made at a suitable Soret wavelength, for example 415 nanometers. DE-A-3700 577 implements a general research method in a specific form and is suitable for measuring arterial oxygen saturation. state that they are doing so. A continuous spectrum of standard characteristics transmitted through the sample to be measured. light from vector light sources to different but overlapping spectra in the visible light range. It is measured using two photodetectors with vector characteristics. One of the outputs of the photodetector Divide by the other side and calculate the quotient “color value (co1ourva1ue)” of the sample used for Proportional for pulling physical data from lookup tables By using color values, this “color value” provides information about the sample. Ru. For example, the color value of a blood sample accurately indicates the wavelength of transmission and therefore the oxygen saturation. give information about There is no mention of the specific wavelength of the photodetector. two The quotient of the photodetector output is essentially the significant signal obtained from the comparison method.

The various deficiencies mentioned above can be solved by using comparisons of output signals to obtain values that are useful in actual trade. This is the basis for all the above methods with points.

Our aim is to avoid these adverse effects by applying basic measurement methods. It is the purpose of light.

[Invention disclosure code] According to one aspect of the invention, blood absorption within the wavelength range of 350 to 600 nanometers. Measure absorption properties with nanometer precision to determine nanometer specific absorption properties The actual oxygen saturation is determined by the wavelength shift of the specific absorption characteristic from the known physiological endpoint. A method of measuring oxygen saturation in a subject's blood, including directly determining the oxygen saturation percentage. is provided.

This method directs light along a blood measurement path and a control path, and selects the light from the path. and applying the selected light to an optical detector. Blood is tested Exists as a body or sample.

This method changes the wavelength of light in units of nanometers, or changes the wavelength of light in units of nanometers, or The light from the irradiated blood is dispersed as a spectrum, and the characteristic The method may include examining the spectrum to obtain a specific wavelength shift.

According to another aspect of the invention, within the range of at least 350 to 600 nanometers. means capable of supplying light in bundles of light of various wavelengths, means for applying said light to the blood measurement path; , means for dispersing light received from the path as a spectrum, light of the spectrum; means for detecting and determining the specific absorption characteristics of a blood measurement route and nanometer scale of said characteristics. Ophthalmology includes a means to suggest the oxygen saturation of the blood in the blood measurement path from the A ximeter is provided.

According to yet another aspect of the invention, the nanometer range is within the range of 350 to 600 nanometers. means for providing light with a variable wavelength that can be controlled metrically, the controllable variable wavelength; means for applying light to a fixed path of blood; detecting the light received from said path; Means for determining specific absorption properties of a measurement path and nanometer wavelength shifts of said properties oximeter including means for indicating the oxygen saturation of the blood in the blood measurement path from - will be provided.

The light may alternately be applied to the detector through separate paths, and the absorption wavelength information may be Testing may be done in any convenient manner for providing the test.

The oximeter has a light for measurement in the blood measurement path and the control path that does not contain blood. means for applying the light from said path alternately and a means for detecting the light for comparative detection; and means for applying it to the stage. The means of applying light alternately may be mechanical or or other optical beam choppers. Comparative test of oximeter A light source of known intensity/wavelength characteristics may be included to avoid the need for radiation.

This method is based on the wavelength shift in the absorption peak of the Tsuretos vector and the oxygen saturation percentage. It uses a direct relationship with changes in the

In a preferred arrangement of the invention, from the known physiological endpoints, 400 to 450.465 520 and 530 to 600 nanometers, more specifically from 410 to 600 nanometers, respectively. 440.1 in the range of 470 to 515 and 540 to 570 nanometers The absorption wavelength is determined by applying the gradient method to the absorption characteristics at each point.

Conveniently, gradient or other suitable absorption spectra analysis is performed using a microprocessor. Implemented within the server. The proportional method may be more convenient in some cases, but if the wavelength information is sufficiently secure. Absolute measurement is possible if the

In a more preferred arrangement, wavelengths in the range of 400 to 600 nanometers are applied to fingernails. Used when measuring through. Apply light to the blood through the nail and return from the blood Optical fibers can be used to receive the incoming light.

The above range has two ends that emit light to the test blood and one that receives light from the blood. It is possible to perform measurements inside the subject, including the means of introducing optical fibers that remove It may also contain a needle for use.

Note that oxidized blood also contains oxygen as oxyhemoglobin and HbO2. The remaining blood is known as reduced hemoglobin, or Hb.

Embodiments of the invention will now be described with reference to the accompanying drawings.

[Brief explanation of the drawing] Figure 1a, lb shows 100% and It is a diagram showing the change characteristics of light absorption of blood depending on wavelength at O% oxygen saturation, Enlarged details.

FIG. 2 is a block diagram of the oximeter of the present invention.

3 and 6 represent graphs useful in understanding the present invention.

Figures 4 and 5 represent arrangements for applying the oximeter of the invention to a patient.

[BEST MODE FOR CARRYING OUT THE INVENTION] Figure 2 shows the oxygen saturation level of blood when blood is applied as a sample. 2 is a schematic block diagram of the elements of a simeter; FIG.

The light emitted from the light source 1o, such as a crystal-halogen lamp, is Scanning monochromator-11 such as (PTR optics, USA) supplied to Scanning monochromator is 350 to 600 nanometers can be operated to produce light output with nanometer precision in the range of You should choose a product with a range of 350 to 600 nanometers in the monochromator. Optical gratings with maximum efficiency in the meter range or by introducing suitable components This is achieved by − The supply to the lamp is stabilized and the lamp and monochromator work together to provide monochromatic illumination. The wavelength band is determined by the physical parameters of the monochromator. stipulated. Wavelength band below 4 nanometers, preferably below 1 nanometer Although a wavelength band of Wavelength band below 5 nanometers area may be preferable. The monochromator has a control connection 12.

The nanometer light from the monochromator 11 is transmitted to the first beam splitter 21. The beam splitter 21 emits two outgoing beams. One ray 27 is for a control and the other beam 28 is applied to the sample in the holder 22.

Mirrors 23, 24 conveniently return the contrast output to a second beam splitter 25; The beam splitter 25 separates the reference beam 27 and the light that has passed through the sample holder 22. It acts to put the light ray 29 from the ray 28 into a common path. Phase dependent detection A beam chopper 26 is arranged to synchronize and cut off the beam so that the place

The optical detector 31 detects the intensity of light emitted from the beam splitter in the common path. , the detector output passes through a Ronfin amplifier 32 and a connection 3 to a beam chopper 26. 3 and is supplied to the microprocessor-34. Micropro 77 sir A bidirectional link 12 connects to a scanning monochromator.

Or the need for a control channel and an optical chopper to produce it. To avoid this, ultrastable light sources can also be used. The illumination characteristics of this light source are It is stored in the microprocessor's memory and used to correct measurements.

By correlating the output of the monochromator 11 and the detector 31, the holder The wavelength at which the absorption of the sample within 22 is maximum or minimum is determined.

Other aspects of the invention are described below with reference to a modification of the arrangement of FIG. In Figure 2 , elements 11 and 34 are omitted, and element 31 is replaced by a prism or a diffraction grating. a dispersion device for responding to the spectrum produced by the dispersion device; A linear detector in the form of a charge-coupled device (CCD) is arranged. Optical instead of element 11 A band-pass filter may also be provided. The operation is as follows. Crystal-Halogen The light from the light source 10, which is a lamp, is is applied to the first beam splitter 21, and the beam splitter 2 is applied to the first beam splitter 21. 1 emits two output rays. One ray 27 is for control, the other ray 28 applied to the sample in holder 22. Mirrors 23 and 24 direct the reference output to the second The beam splitter 25 conveniently returns the reference beam to the beam splitter 25. 27 and the light ray 29 from the light ray 28 that passed through the sample holder 22 on a common path. It has the effect of putting it in. Tuning the beam to obtain phase-dependent detection Beam chopper 26 is placed to block it.

The common path light from the beam splitter enters a dispersion device, which divides the optical spectrum. This optical spectrum is the result of the detection of the material in the sample holder and the control beam. Alternately related to the system. The spectrum formed in this way has the most foreground color wavelength. Add a charge-coupled element to the first element, with the reddest wavelength being the last element (or vice versa). Arranged so that it falls on the element of the child (CCD) array! be done. Collects optical spectrum information To assemble, the CCD is scanned from the first element to the last element. this Scanning is conveniently carried out under microprocessor control via suitable circuit connections. element information is passed back to the microprocessor via other circuit connections. It will be done. The entire process is done in a matrix to create sample and control spectral information. The microprocessor tunes the beam chopper 26 via the coupling 33. It will be done.

Alternatively, as in the first embodiment, a control channel and an optical chip for producing the control channel may be used. Ultra-stable light sources can also be used to avoid the need for a chopper. this The illumination characteristics of the light source are stored in the microprocessor's memory and used to correct measurements. I can stay.

Algorithms within the microprocessor determine specific absorption within a range of known physiological endpoints. In order to obtain a shift in yield characteristics, the specific characteristics of the sample in the sample holder 22 are Provides a means for absorption wavelength determination.

As shown in Figure 3, blood oxygen saturation is between 400 and 450 nanometers. Correlates with the wavelength of peak absorption in the overhead range. As shown in the inset of Figure 1, 0 There are separate peaks in the absorption characteristics at % and 100% oxygen saturation. This other The presence of different peaks indicates an identifiable change in the absorption with constant oxygen saturation. Tarasu. Therefore, absorption peaks in this range can be determined by quick and simple sample measurements. Oxygen saturation can be assessed and suggested from the determination of The graph in Figure 3 is for convenience. Determine the peak that was found to be relevant, i.e. determine the percent oxygen saturation. It concerns a particular method of doing so. Obviously other methods involve other graphs. However, such modifications do not depart from the scope of the invention. The method used was A gradient method, in which characteristic absorption inflection points on each side of the absorption peak are The intersection point of the slope is used to indicate the wavelength of the peak. Therefore, "Peak" need not be a peak in optical terms to embody the present invention. A specific type of attire used for! is a parameter that can be determined repeatedly. 465? 520 and 530 to 600 nanometers have characteristic separate peaks. or troughs or valleys exist, hence repeating an identifiable change in the absorption at a constant saturation. It can be used as a possible parameter. Figure 6 is a graph similar to Figure 3. or for a valley in the 480 to 500 nanometer range.

Sample safety methods and manipulation methods are known and are applicable to the present invention. static sample For continuous sample flow, use a removable optical cuvette. can be used.

In the arrangement described above, the light passes through the sample in the holder, i.e. 1 nvi This is the tro method. Avoids the need to take samples from patients in medical applications This is known as non-invasive and in vivo methods, respectively. It is being

FIG. 4 is a schematic diagram of a device that allows the arrangement of FIG. 2 to be applied to a patient without penetrating the skin. It is. In the apparatus of FIG. 4, the optical chamber 22 of FIG. 2 is replaced. beam 28 The light from is guided along optical fiber 43 by mirror 41. Holder 4 5 is an essentially normal finger or toe so that the light beam 48 passes through the nail. The optical fiber 43 is placed on top of the nail. More fiber optics 44 is placed by the holder 45, which is generally indicated at 49, The light from the optical fiber 43 reflected from the capillary bed is collected. to optical fiber 44 Therefore, the collected light advances to the beam chopper 26 by the mirror 42, and then is similar to the arrangement in FIG.

Figure 5 shows when the arrangement of Figure 2 is applied by drilling into a patient's vein, artery or organ. FIG. Optical fiber and holder (43, 44, 45) in Figure 4 Alternatively, a structure 51 such as a hypodermic needle or an internal flexible catheter may be used to This accommodates two optical fibers 52,53. Structure 51 generally pierces the skin. to bring the output and input ends of the fibers 52 and 53 to the area of interest. Delivery! be done. Light 58 exiting optical fiber 52 is directed from the area of interest to the optical fiber. It passes through the bar 53 and returns as light 59 for recovery. Element 28.41.42 and 26 are the same as above.

The general technique of the above device is obvious to those skilled in the art and will not be described further.

Microprocessor control is used as described above. Typical arrangement and operation are as follows. It is as below.

The instrument operates under microprocessor control. scanning monochrome The motor is driven by a combination of a stepper motor and a gearbox. My A croprocessor monitors the position of the grating, which determines the wavelength of the light, and uses this information. and a digitized signal obtained from an optical detector. Then all these information is stored as bit patterns in random access memory (RAM). Ru. Digital optical detector output scanning for maximum or minimum peaks oxidation scanning is also possible. To determine the wavelength of maximum or minimum absorption peak The mathematical operations are contained within the microprocessor software. blood specs Data regarding the torque test characteristics are stored in the memory of the device. About the sample Once all calculations have been completed, the lookup table is created using this peak wavelength value as a guideline. to know the oxygen saturation of the sample. The various types accumulated in the lookup table Using the test parameters, the clinical condition can be adjusted to obtain the statistically best oxygen saturation. The equipment is designed with a wide range of options so that the most appropriate characteristic or characteristic group can be selected depending on the situation. can be checked to improve accuracy.

Monochromator - includes one or more standard wavelength sources in the scanning system. This provides an optical comparison point. This allows the microprocessor to become a monolith. Chromator can be tested.

In principle, the device can handle samples such as pH, pcOz and other hemoglobin derivatives. Measurement circuits based on prior art techniques for measuring other parameters present in It can include roads, sensors and algorithms. Scanning elements mentioned above In addition, this makes it a comprehensive device that can be used as a laboratory standard. Ru.

The improvement provided by the present invention is that the maximum or minimum peak Direct basic measurement of oxygen saturation by measuring the absorption wavelength of It is important to note what was obtained.

Rri, 1a Macho Fri, 1b If l) Submission of translation of written amendment (Article 184-8 of the Patent Act) January 27, 1992

Claims (1)

[Claims] 1. Nanometer absorption properties of blood within the wavelength range of 350 to 600 nanometers measurements to determine nanometer-specific absorption properties and to meet known physiological limits. The actual percent oxygen saturation can be directly determined by the wavelength shift of the specific absorption characteristic from the point A method of measuring oxygen saturation of blood under test, comprising: determining. 2. Guide the light along the blood measurement path and the control path, and select the light from the paths alternately. and applying the selected light to an optical detector. Method. 3. Claim 1 that includes providing blood as a subject or sample Method described. 4. Claim 1 includes changing the wavelength of light in nanometer units. How to put it on. 5. Irradiate the blood with bundles of light of various wavelengths and use the light from the irradiated blood as a spectrum. dispersion and examining the spectrum to obtain the wavelength shift of the characteristic. The method of claim 1 comprising: 6. Light in bundles of light of various wavelengths within the range of at least 350 to 600 nanometers means for applying said light to a blood measurement path; Means for dispersing light as a spectrum, detecting the light in the spectrum and creating a blood measurement path A means of determining the specific absorption properties of blood and blood measurements from nanometer shifts in these properties. An oximeter containing a means of indicating the oxygen saturation of the blood in the regular path. 7. Light is dispersed by a diffraction grating and detected by an array of elements in a charge-coupled device. The oximeter according to claim 6. 8. Claims in which the range of light beams of various wavelengths is set by a bandpass filter The oximeter according to paragraph 6. 9. Variable that can be controlled in nanometers within the range of 350 to 600 nanometers. means for providing a wavelength of light, the controllable variable wavelength of light being applied to the blood measurement path; means, detecting light received from the pathway to determine specific absorption characteristics of the blood measurement pathway; of blood in the blood measurement path from the nanometer wavelength shift of the characteristic. Oximeter with means to suggest oxygen saturation. 10. Pass the light alternately through separate paths to the detector to provide absorption wavelength information The oximeter according to claim 9, which applies to. 11. Hands applying light for measurement to the blood measurement path and the control path not containing blood applying the light from the stage and the path alternately to the means for detecting light for comparative detection. 10. The oximeter according to claim 9, comprising means for: 12. The means for alternating the application of light includes a mechanical or other light beam chopper. The oximeter according to claim 11. 13. Claims containing light sources of known intensity/wavelength characteristics to avoid the need for comparative detection The oximeter according to item 9. 14. Apply light from a light source and pass it through the test blood in vivo. A means of guiding the light that has passed through the blood in vivo for wavelength shift determination. 10. The oximeter according to claim 9, further comprising means for accommodating the oximeter. 15. Wavelength shift in absorption peak of Solet spectrum and percent oxygen saturation A method of measuring the oxygen saturation level of the test blood based on its direct relationship with changes in blood pressure. 16, from known physiological endpoints, 400 to 450, 465 to 520 and 530 600 nanometers, more specifically 410 to 440 and 470 to 5 nanometers, respectively. 15 and absorption characteristics in one of the ranges from 540 to 570 nanometers. Claim 1 comprising applying a gradient method to determine the wavelength of the specific absorption characteristic. or the method described in paragraph 15. 17. Oxygen saturation of test blood as essentially described herein with reference to the accompanying drawings How to measure. 18. An oximeter essentially as herein described with reference to the accompanying drawings.