Near-infrared tissue oxygen monitoring system and method

Abstract

The invention discloses a near-infrared tissue oxygen monitoring system which comprises a near-infrared blood oxygen probe, a circuit acquisition board and an upper computer system, the near-infrared blood oxygen probe is connected with the circuit acquisition board, and the circuit acquisition board is connected with the upper computer system; the near-infrared blood oxygen probe comprises two light source emitting devices and three light source receiving sensors which are connected with the circuit acquisition board, the two light source emitting devices are used for emitting infrared light with different wavelengths respectively, and the light source receiving sensors are used for receiving and transmitting optical signals; and the upper computer system is used for solving the current tissue oxygen value. The near-infrared tissue oxygen monitoring system can monitor the oxygen state of the biological local tissue counteracting ambient light, monitoring data are more accurate, the structure is simple and small, and the near-infrared tissue oxygen monitoring system is particularly suitable for ischemia reperfusion of small animals.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical devices, and particularly to a near-infrared tissue oxygen monitoring system and method. Background Art

[0002] In the field of biomedical research, ischemia-reperfusion is a phenomenon of great significance and has received much attention. It is widely involved in various clinical scenarios. For example, during the treatment of vascular obstructive diseases such as myocardial infarction and stroke, when blood flow is restored, the tissue organs suffer additional damage. This complex pathophysiological process seriously affects the prognosis of the disease and the quality of life of patients. The establishment of animal ischemia-reperfusion models provides key tools and means for in-depth exploration of this mechanism and the development of effective treatment strategies.

[0003] From the basic physiological level, normal blood circulation is crucial for maintaining the function of tissue organs. Blood not only transports oxygen and nutrients but also removes metabolic wastes, maintaining the stability of the intracellular environment. When ischemia occurs, the blood supply to the tissue organs is suddenly interrupted, resulting in a lack of oxygen and nutrients. Cells quickly enter an anaerobic metabolic state, producing a large amount of metabolic products such as lactic acid accumulation. At the same time, energy generation is blocked, the ATP level drops sharply, the ion pump function on the cell membrane is damaged, and intracellular calcium overload occurs, triggering a series of cytotoxic reactions, such as activating proteases, nucleases, etc., leading to the destruction of cell structure and function.

[0004] When the ischemic state is relieved and blood reperfusion occurs, the tissue organs that were originally on the verge of injury fail to quickly return to normal and instead suffer a more severe secondary hit. This is because a series of complex pathophysiological reactions are triggered during the reperfusion process. First, a large amount of reactive oxygen species are generated, including superoxide anion, hydrogen peroxide, and hydroxyl free radicals. These reactive oxygen species mainly originate from the reactivated mitochondrial respiratory chain, xanthine oxidase system, and infiltrated neutrophils after reperfusion.

[0005] In addition, the reperfusion process promotes the outbreak of inflammatory reactions. Ischemic tissues release a variety of inflammatory mediators during reperfusion, which attract a large number of neutrophils to infiltrate into the tissues. Vascular endothelial cells are also damaged during ischemia-reperfusion, and their normal anticoagulant, anti-inflammatory, and vascular tension regulation functions are disordered, resulting in increased vascular permeability, microthrombus formation, and microcirculation disorders, further aggravating the tissue ischemia and hypoxia state.

[0006] The middle cerebral artery occlusion or bilateral common carotid artery occlusion methods are often used in the cerebral ischemia-reperfusion model to simulate the cerebral ischemia process, and then the blood flow is restored to study the evolution of the infarct area, the apoptosis and necrosis mechanisms of nerve cells, and the recovery of nerve function. This is crucial for the treatment research of stroke and provides an experimental basis for finding effective neuroprotective agents and improving the prognosis of stroke patients.

[0007] The establishment and application of animal ischemia-reperfusion models have greatly promoted our understanding of the mechanisms of ischemia-reperfusion injury, built a bridge for translational medicine research, enabled basic research results to be more effectively applied to clinical practice, provided a solid theoretical basis and experimental evidence for improving the treatment effect and prognosis of patients, and will continue to play an important role in future biomedical research, leading us to continuously explore new methods and approaches to combat ischemia-reperfusion injury and make greater contributions to the cause of human health.

[0008] However, there is still a lack of effective means for monitoring tissue oxygen in the current state of ischemia and reperfusion in animals. Therefore, there is an urgent need for a tissue oxygen monitoring system to observe the oxygen in ischemic brain tissue, so as to solve the research on the mechanism of this model. Summary of the Invention

[0009] The purpose of the present invention is to provide a near-infrared tissue oxygen monitoring system and method, which can monitor the local tissue oxygen state of living organisms that offsets environmental light, with more accurate monitoring data, simple and compact structure, especially applicable to the near-infrared tissue oxygen monitoring system for small animal ischemia-reperfusion.

[0010] The technical solution adopted by the present invention is: A near-infrared tissue oxygen monitoring system includes a near-infrared blood oxygen probe, a circuit acquisition board, and a host computer system for signal reception. The near-infrared blood oxygen probe is connected to the circuit acquisition board, and the circuit acquisition board is connected to the host computer system; The near-infrared blood oxygen probe includes two light source emission devices connected to the circuit acquisition board and three light source receiving sensors. The two light source emission devices are used to emit light of different wavelengths respectively, and the light source receiving sensors are used for receiving and transmitting optical signals; the host computer system is used to solve the current tissue oxygen value according to the received optoelectronic signals.

[0011] Preferably, the light of different wavelengths emitted by the two light source emission devices is red light and infrared light respectively; The wavelengths of the red light and the infrared light are respectively in the range of 620 - 750 nm and 800 - 900 nm.

[0012] Preferably, the acquisition circuit board includes a core processing module, and a clock crystal oscillator, a radio frequency antenna, a battery, and a power management chip connected to the core processing module.

[0013] Preferably, the three light source receiving sensors are evenly distributed at equal intervals along a straight line, and the distance between adjacent light source receiving sensors is 5 to 10 mm.

[0014] Preferably, the light source emitting device is a light-emitting diode, and the light source receiving sensor is a photoelectric sensor.

[0015] A method for monitoring tissue oxygen by using the near-infrared tissue oxygen monitoring system as described above includes the following steps: Step 1, two light source emitting devices emit two lights with different wavelengths; Step 2, the two emitted lights are absorbed and scattered by biological tissue and then received by the light source receiving sensors. Two of the three light source receiving sensors are used as tissue oxygen acquisition receivers, and the remaining one is used as an ambient light receiver; Step 3, the light source receiving sensors convert the collected optical signals into electrical signals, and the corresponding data signals are transmitted to the upper computer system through the circuit acquisition board; Step 4, the upper computer system calculates the tissue oxygen saturation of the biological tissue offsetting the ambient light through the data signals collected by the three light source receiving sensors.

[0016] Preferably, the two lights with different wavelengths emitted by the two light source emitting devices are the first wavelength light and the second wavelength light respectively, and the three light source receiving sensors are the first light source receiving sensor, the second light source receiving sensor, and the third light source receiving sensor respectively; In the above-mentioned step 4, the specific process for the upper computer system to calculate the tissue oxygen saturation of the biological tissue offsetting the ambient light through the data signals collected by the three light source receiving sensors is as follows: The first sensor oxygen saturation value is obtained according to the light intensity of the first wavelength light and the light intensity of the second wavelength light detected by the first light source receiving sensor and the second light source receiving sensor ; The second sensor oxygen saturation value is obtained according to the light intensity of the first wavelength light and the light intensity of the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor ; The third sensor oxygen saturation value is obtained according to the light intensity of the first wavelength light and the light intensity of the second wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor ; According to the first sensor oxygen saturation value 、the second sensor oxygen saturation value and the third sensor oxygen saturation value the tissue oxygen saturation of the biological tissue offsetting the ambient light is obtained.

[0017] Preferably, the first sensor oxygen saturation value is obtained based on the light intensities of the first-wavelength light and the second-wavelength light detected by the first light source receiving sensor and the second light source receiving sensor The specific process is as follows: Take the partial derivative of the difference in the light intensities of the first-wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path Take the partial derivative of the difference in the light intensities of the second-wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path ; According to and Calculate to obtain the first sensor oxygen saturation value .

[0018] Preferably, the second sensor oxygen saturation value is obtained based on the light intensities of the first-wavelength light and the second-wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor The specific process is as follows: Take the partial derivative of the difference between the light intensity of the first-wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path Take the partial derivative of the difference between the light intensity of the second-wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path ; According to and Calculate to obtain the second sensor oxygen saturation value .

[0019] Preferably, the third sensor oxygen saturation value is obtained based on the light intensities of the first-wavelength light and the second-wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor The specific process is as follows: Take the partial derivative of the difference between the light intensity of the first-wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path Take the partial derivative of the difference between the light intensity of the second-wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path ; According to and Calculate to obtain the third sensor oxygen saturation . The beneficial effects of the present invention are: The present invention emits lights of different wavelengths through two light source emission devices, and receives corresponding optical signals through a light source receiving sensor. Two of the three light source receiving sensors are used as tissue oxygen collection receivers, and the remaining one is used as an ambient light receiver, so as to be able to monitor and offset the biological local tissue oxygen state of the ambient light. The monitoring data is more accurate, and the structure is simple and compact. In particular, it is applicable to a near-infrared tissue oxygen monitoring system for small animal ischemia-reperfusion, which promotes our understanding of the mechanism of ischemia-reperfusion injury, builds a bridge for translational medicine research, enables the basic research results to be more effectively applied to clinical practice, and provides a solid theoretical basis and experimental basis for improving the treatment effect and prognosis of patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of the near-infrared tissue oxygen monitoring system in an embodiment of the present invention.

[0021] Figure 2 is an electrical schematic diagram of the near-infrared tissue oxygen monitoring system in an embodiment of the present invention.

[0022] Figure 3 is a schematic diagram of an animal brain ischemia-reperfusion model in an embodiment of the present invention.

[0023] Figure 4 is a working schematic diagram of the near-infrared tissue oxygen monitoring system applied to an animal brain ischemia-reperfusion model in an embodiment of the present invention.

[0024] Figure 5 is a monitoring data diagram of the near-infrared tissue oxygen monitoring system when it is used for an animal brain ischemia-reperfusion model in an embodiment of the present invention.

[0025] Figure 6 is a schematic diagram of light passing through a container or tissue with a certain thickness L in an embodiment of the present invention.

[0026] In the figure: 101 - First light-emitting diode; 102 - Second light-emitting diode; 103 - Flexible circuit board substrate; 104 - FPC flexible cable; 105 - Circuit acquisition board; 106 - Wireless transmission; 107 - Host computer system; 201 - 635nm red light; 202 - 850nm infrared light; 203 - First photodiode; 204 - Second photodiode; 205 - Third photodiode; 206 - STM32 core processing module; 207 - Clock crystal oscillator; 208 - Power management chip; 209 - Battery; 210 - RF antenna; 211 - Serial port; 212 - Program download port; 213 - Algorithm processing module; 214 - Host computer system; 301 - External carotid artery; 302 - Middle artery; 303 - Internal carotid artery; 304 - Vascular clamp; 305 - Ipsilateral common carotid artery; 306 - Contralateral common carotid artery; 401 - Rat; 402 - Acquisition front end; 501 - Invisible control group; 502 - Experimental group. Detailed implementation mode

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] In the description of the present invention, it should be understood that if there are terms involved such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0029] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. It may be a mechanical connection or an electrical connection. It may be directly connected or indirectly connected through an intermediate medium. It may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Example 1 A near-infrared tissue oxygen monitoring system, Figures 1 to 5 As shown, it includes a near-infrared blood oxygen probe, a circuit acquisition board 105, and a host computer system for signal reception. The near-infrared blood oxygen probe is connected to the circuit acquisition board through an FPC flexible cable 104, and the circuit acquisition board is connected to the host computer system; The near-infrared blood oxygen probe includes two light source emitting devices connected to the circuit acquisition board 105 and three light source receiving sensors. The two light source emitting devices are used to emit lights of different wavelengths respectively, and the light source receiving sensors are used for receiving and transmitting optical signal data. Due to different distances, the three light source receiving sensors receive red light and infrared light information of different wavelengths simultaneously. The upper computer system is built-in with a tissue oxygen calculation algorithm for quickly solving the current tissue oxygen value.

[0031] Further, the lights of different wavelengths emitted by the two light source emitting devices are red light and infrared light respectively, and the infrared light can be near-infrared light; The wavelengths of the red light and the infrared light are respectively in the range of 620 - 750 nm and 800 - 900 nm.

[0032] Further, the light source emitting device is a light-emitting diode, and the light source receiving sensor is a photoelectric sensor.

[0033] In this embodiment, the light-emitting diode can emit red light with a wavelength of 635 nm and infrared light with a wavelength of 850 nm.

[0034] Because red light has a higher response to hemoglobin and is not sensitive to oxyhemoglobin, while infrared light is just the opposite. Generally, this difference is used to calculate blood oxygen (i.e., the proportion of oxyhemoglobin in the total blood). Therefore, it is not necessarily 850 nm or 635 nm. In our case, the diodes just happen to be selected as 850 nm and 635 nm, and there will be different calculation rules according to different wavelengths.

[0035] Further, the acquisition circuit board includes a core processing module, and a clock crystal oscillator, a radio frequency antenna, a battery and a power management chip connected to the core processing module.

[0036] Further, the 3 light source receiving sensors are evenly distributed at equal intervals along a straight line, and the distance between adjacent light source receiving sensors is 5 - 10 mm.

[0037] Further, the light source emitting device is a light-emitting diode. The two light-emitting diodes are the first light-emitting diode and the second light-emitting diode respectively, and the light source receiving sensor is a photoelectric sensor.

[0038] The photoelectric sensor is a photodiode. The three photodiodes are photodiode one, photodiode two and photodiode three respectively, and the distance between adjacent two photodiodes is 5 mm.

[0039] In the prior art, the distance between the light-emitting diode and the photodiode generally exceeds 20 mm. Because the extinction coefficient within 20 mm is non-linear and it is very difficult to calculate variable parameters. However, in this embodiment, since the sensor is for measuring small animals, the head of a small animal does not exceed 20 mm. The distance between the light-emitting diode and the photodiode is less than 20 mm, about 5 mm. This requires an additional calibration step to accurately measure blood oxygen.

[0040] A method for monitoring tissue oxygen using the near-infrared tissue oxygen monitoring system as described above, comprising the following steps: Step 1, two light source emission devices emit two lights with different wavelengths; Step 2, the two emitted lights are absorbed and scattered by biological tissue and then received by the light source receiving sensor. Two of the three light source receiving sensors are used as tissue oxygen acquisition receivers, and the remaining one is used as an ambient light receiver; Step 3, the light source receiving sensor converts the collected optical signal into an electrical signal, and transmits the corresponding data signal to the host computer system through the circuit acquisition board; Step 4, the host computer system calculates the tissue oxygen saturation of the biological tissue offsetting the ambient light based on the data signals collected by the three light source receiving sensors.

[0041] Further, the two lights with different wavelengths emitted by the two light source emission devices are the first wavelength light and the second wavelength light respectively, and the three light source receiving sensors are the first light source receiving sensor, the second light source receiving sensor and the third light source receiving sensor respectively; In the step 4, the specific process of the host computer system calculating the tissue oxygen saturation of the biological tissue offsetting the ambient light based on the data signals collected by the three light source receiving sensors is as follows: Obtain the first sensor oxygen saturation value according to the light intensities of the first wavelength light and the second wavelength light detected by the first light source receiving sensor and the second light source receiving sensor ; Obtain the second sensor oxygen saturation value according to the light intensities of the first wavelength light and the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor ; Obtain the third sensor oxygen saturation value according to the light intensities of the first wavelength light and the second wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor ; According to the first sensor oxygen saturation value , the second sensor oxygen saturation value and the third sensor oxygen saturation value Obtain the tissue oxygen saturation of the biological tissue offsetting the ambient light.

[0042] Further, a first sensor oxygen saturation value is obtained based on the light intensities of the first wavelength light and the second wavelength light detected by the first light source receiving sensor and the second light source receiving sensor. The specific process is as follows: Take the partial derivative of the difference in the light intensities of the first wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path. Take the partial derivative of the difference in the light intensities of the second wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path. ; Based on and calculate to obtain the first sensor oxygen saturation value. .

[0043] =

[0044] In the formula, is the molar extinction coefficient of hemoglobin for the first wavelength light, is the molar extinction coefficient of oxyhemoglobin for the first wavelength light, is the molar extinction coefficient of hemoglobin for the second wavelength light, is the molar extinction coefficient of oxyhemoglobin for the second wavelength light, is the partial derivative of the difference in the light intensities of the first wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path r, is the partial derivative of the difference in the light intensities of the second wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path r.

[0045] Further, a second sensor oxygen saturation value is obtained based on the light intensities of the first wavelength light and the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor. The specific process is as follows: Take the partial derivative of the difference between the light intensity of the first wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path. Take the partial derivative of the difference between the light intensity of the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path. ; Based on and calculate to obtain the second sensor oxygen saturation value. .

[0046] = ; In the formula, is the molar extinction coefficient of hemoglobin for light of the first wavelength, is the molar extinction coefficient of oxyhemoglobin for light of the first wavelength, is the molar extinction coefficient of hemoglobin for light of the second wavelength, is the molar extinction coefficient of oxyhemoglobin for light of the second wavelength, is the partial derivative of the difference between the light intensity of the first wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path r, is the partial derivative of the difference between the light intensity of the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path r.

[0047] Furthermore, the oxygen saturation value of the third sensor is obtained according to the light intensities of the first wavelength light and the second wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor The specific process is as follows: Take the partial derivative of the difference between the light intensity of the first wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path , and take the partial derivative of the difference between the light intensity of the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path ; According to and calculate to obtain the oxygen saturation based on the third sensor .

[0048] = ; In the formula, is the molar extinction coefficient of hemoglobin for light of the first wavelength, is the molar extinction coefficient of oxyhemoglobin for light of the first wavelength, is the molar extinction coefficient of hemoglobin for light of the second wavelength, is the molar extinction coefficient of oxyhemoglobin for light of the second wavelength, is the partial derivative of the difference between the light intensity of the first wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path r, is the partial derivative of the difference between the light intensity of the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path r.

[0049] Furthermore, the host computer system has a local tissue oxygen curve interface, a setting panel, a data export function, a data calibration function, etc., and is connected to the acquisition circuit board in a wireless manner for data transmission. The wireless methods include WI-FI, Bluetooth, NBIot, NFC, etc.

[0050] Furthermore, according to the molar extinction coefficient of hemoglobin for the first-wavelength light , the molar extinction coefficient of oxyhemoglobin for the first-wavelength light , the molar extinction coefficient of hemoglobin for the second-wavelength light , the molar extinction coefficient of oxyhemoglobin for the second-wavelength light , and the medium absorption coefficient of the first-wavelength light and the medium absorption coefficient of the second-wavelength light , the tissue oxygen saturation is calculated.

[0051] Furthermore, according to the molar extinction coefficient of hemoglobin for the first-wavelength light , the molar extinction coefficient of oxyhemoglobin for the first-wavelength light , the molar extinction coefficient of hemoglobin for the second-wavelength light , the molar extinction coefficient of oxyhemoglobin for the second-wavelength light , and the medium absorption coefficient of the first-wavelength light and the medium absorption coefficient of the second-wavelength light , the content of oxyhemoglobin and the content of hemoglobin are calculated.

[0052] Furthermore, the partial derivative formula of the optical density of the first-wavelength light with respect to the optical path r and the partial derivative formula of the optical density of the second-wavelength light with respect to the optical path r are used to calculate the ratio of the medium absorption coefficient of the first-wavelength light to the medium absorption coefficient of the second-wavelength light .

[0053] Example 2 For the monitoring of the near-infrared tissue oxygen monitoring system for animal ischemia-reperfusion, the near-infrared tissue oxygen monitoring system is attached to the epidermis of the animal's measurement site to measure the blood oxygen change in the brain tissue, and then the animal is reperfused to observe the trend of blood oxygen and check whether the cerebral infarction model is successful during the modeling process of the animal The construction process of the animal ischemia-reperfusion model is as follows: Step S1: After the rat is anesthetized intraperitoneally, it is fixed in the supine position on the operating table. The skin is routinely prepared and disinfected, and the whole operation is kept warm. The incisors of the mouse are hooked and fixed with a suture to stretch the neck; Step S2: Attach the front end of the near-infrared tissue oxygen monitoring system to the ipsilateral side of the rat's brain (the measurement site is near the aortic blood vessels along the left and right hemispheres of the rat's brain), and place it in the supine position for fixation again; Step S3: Incise the middle of the neck with a conventional scalpel, bluntly separate the neck glandular tissue and fascia with forceps, expose and separate the common carotid artery (CCA), external carotid artery (ECA), and internal carotid artery (ICA), and turn on the system for brain tissue oxygen monitoring; Step S4: Separate the ICA and its extracranial branch, the pterygopalatine artery. Tie a slipknot with a suture to ligate the pterygopalatine artery, or directly clamp the pterygopalatine artery with a vascular clip to prevent the suture from being inserted into the pterygopalatine artery, and keep the only open branch of the CCA as the ICA, and observe the change of brain tissue oxygen; Step S6: Separate the main trunk of the ECA, ligate the distal and proximal ends of the external carotid artery (leave long thread ends), and the interval is 5 mm. Cut the artery between the two ligation points. Then gently pull the proximal thread end to make this section of the artery consistent with the course of the common carotid artery, and observe the change of brain tissue oxygen; Step S8: Use a micro-artery clip to clamp the proximal end of the bifurcation of the common carotid artery and the external carotid artery, and then cut a small opening in the remaining segment of the external carotid artery, insert the pre-prepared suture until the origin of the middle cerebral artery, and observe the change of brain tissue oxygen; Step S7: After ligation and disinfection, suture the subcutaneous tissue and skin layer by layer. After the animal wakes up from anesthesia, put it back into the cage, and observe the change of brain tissue oxygen; Step S8: For another part of the rats, directly pull out the suture and observe the change of brain tissue oxygen.

[0054] Furthermore, the usage method of the near-infrared tissue oxygen monitoring system for animal ischemia-reperfusion is as Figure 4 shown, wherein the front end 402 is attached to the ipsilateral and contralateral sides of the rat's 401 brain to observe the change of brain tissue oxygen.

[0055] Furthermore, the monitored data is as Figure 5 shown. For the negative control group 501, the blood oxygen remains unchanged under ischemic and reperfusion conditions because the blood flow is not flowing and has no effect on the change of tissue oxygen. While in the ipsilateral side of the experimental group 502, there is an obvious decrease in tissue oxygen during ischemia, and there is an upward trend after reperfusion, and then it maintains a stable state, indicating that the system can stably monitor the ischemia and reperfusion conditions of animal tissue oxygen.

[0056] Furthermore, the host computer software includes a host computer visualization interface written in Python language and an algorithm program written in internal C++. It includes a visual host computer waveform display interface, which can be used to observe the change state of tissue oxygen in real time. The calibration value is used to display the calibration value of the currently calibrated optical component. The function bar is used to export data and re-measure, etc. Calibration is used to calibrate the optical component at the initial stage of use. The setting bar is used to set patient data, data range, etc.

[0057] The present invention utilizes the modified Lambert-Beer law to measure tissue oxygen data in real time after optical input, and observes the whole process of the change of brain tissue oxygen under the condition of animal ischemia-reperfusion, which has far-reaching significance for the clinical aspect. The highly integrated acquisition backend and the data connection line form a stable electrical connection to ensure the faithful transmission of data. This electrode clip has the properties of high fidelity, wide linear range and low artifacts, and sends the signal to the host computer system for display through reliable transmission protocols such as Bluetooth, WI-FI and USB in the market. The present invention can observe the state of animal ischemia-reperfusion in real time, build a bridge for translational medicine research, enable the basic research results to be more effectively applied to clinical practice, and provide a solid theoretical basis and experimental basis for improving the treatment effect and prognosis of patients.

[0058] The working principle of the present invention: When photons enter biological tissue, they will interact with the tissue such as absorption and scattering. The interaction law between photons and biological tissue can be accurately described by the photon transport equation. However, it is very difficult to solve the photon transport equation. Considering the characteristics of strong scattering of human tissue, the diffusion equation can be used to approximate the photon transport equation; As Figure 6 shown, the schematic diagram of light passing through a container or tissue with a certain thickness L. According to the Lambert-Beer law, assuming that there is a pure absorption medium with a concentration of C in a container or tissue with a certain thickness L, the incident light is and the transmitted light is . Using the absorption law, it can be known that ; 1 where is the absorption coefficient of the medium, and the unit is mm -1 . Integrating the above formula, it can be obtained that ; 2 According to formula 2, the calculation formula for the light intensity attenuation after passing through multiple absorbers is:

[0059] where is the transmitted light intensity detected by the detector, is the emission light intensity of the light source, is the i-th absorption coefficient of the absorber, is the optical path (here the optical path refers to the distance from the incident point to the exit point); The optical density OD (optical density) is defined as, ; 3 According to Formulas 2 and 3, it can be known that, ; 4 In blood, it can be assumed that is proportional to , and thus it can be obtained that, the absorption system coefficient of the medium ; 5 wherein, is the molar extinction coefficient of the absorber, which can be obtained by looking up the table, and its unit is L(mmol·mm) or (mmol·cm), C is the concentration of the absorption medium. By combining Formulas 4 and 5, it can be obtained that, ; 6 The selected infrared light and red light bands in this patent are respectively , , according to the above situation, in the near-infrared band, the main media are oxyhemoglobin and hemoglobin . According to Formula 5, it can be known that, ; 7 can be approximately expressed as, ; 8 In the formula, is the content of oxyhemoglobin in local tissue, is the content of hemoglobin in local tissue, is the molar extinction coefficient of oxyhemoglobin, is the molar extinction coefficient of hemoglobin; According to the above formula, combining the two bands, it can be obtained that, ; 9-1 ; 9-2 According to the definition of tissue oxygen saturation, it can be known that, ; 10 In the formula, is the molar extinction coefficient of hemoglobin for light of the first wavelength, is the molar extinction coefficient of oxyhemoglobin for light of the first wavelength, is the molar extinction coefficient of hemoglobin for light of the second wavelength, is the molar extinction coefficient of oxyhemoglobin for light of the second wavelength, is the medium absorption coefficient of light of the first wavelength, is the medium absorption coefficient of light of the second wavelength; According to Equation 10, it can be known that The calculation of .

[0060] Assuming that the system is a homogeneous infinite medium, according to the Helmoholtz equation, combined with the Green function, based on the analytical solution of the diffuse reflection equation, an approximate value of the diffuse reflection intensity far from the light source can be obtained: ; 11 In the formula, A is the cross-sectional area of the medium space, and r refers to the optical path from the incident point to the exit point; Combined with the definition of optical density, ; 12 Among them, is the diffuse reflection intensity, is the scattering coefficient of the medium, ; Combined with Equations 11 and 12, ; 13 The last two terms in Equation 13 are independent of , so taking the partial derivative of to eliminate the last two terms, the partial derivative expression of the light intensity OD with respect to the optical path is: ; 14 Finally, an expression of OD with respect to the extinction coefficient and the reduced scattering coefficient is obtained. Among them, in the near-infrared band, is independent of the wavelength, , and can be written as ; 15 In the formula, is the medium absorption coefficient, is the partial derivative of the difference in the light intensities detected by the two light source receiving sensors for the corresponding light with respect to the optical path; That is, ; 16 In the formula, is the medium absorption coefficient of the first wavelength light, is the medium absorption coefficient of the second wavelength light, and λ1 and λ2 are the wavelengths of the different wavelength lights emitted by the two light source emission devices respectively, is the partial derivative of the difference in the light intensities of the first wavelength light detected by the two light source receiving sensors with respect to the optical path, is the partial derivative of the difference in the light intensities of the second wavelength light detected by the two light source receiving sensors with respect to the optical path, and r is the optical path; According to Equation 16 and combined with Equation 10, it can be known that, ; 17 In the formula, is the molar extinction coefficient of hemoglobin for the first wavelength light, is the molar extinction coefficient of oxyhemoglobin for the first wavelength light, is the molar extinction coefficient of hemoglobin for the second wavelength light, is the molar extinction coefficient of oxyhemoglobin for the second wavelength light, is the partial derivative of the difference in the light intensities of the first wavelength light detected by the two light source receiving sensors with respect to the optical path, is the partial derivative of the difference in the light intensities of the second wavelength light detected by the two light source receiving sensors with respect to the optical path, and r is the optical path; According to Equation 17, it can be known that by calculating and the value of the current blood oxygen saturation can be obtained.

[0061] In addition, if you want to continue to obtain the contents of oxyhemoglobin and hemoglobin, the following calculations are required, ; 18 In the formula, is a proportionality coefficient, is a constant, λ is the wavelength of the emitted light, and here we take to obtain the expression of the relative absorption coefficient by back-solving: ; 19 ; 20 - 1 ; 20 - 2 By solving the equations simultaneously, the solutions of and can be obtained: ; 21 ; 22 ; 23 Since three photodiodes are used as light source receiving sensors, namely PD1, PD2, and PD3, three partial derivatives of OD with respect to the optical path can be obtained. We assume that these three values are respectively , , , where refers to the partial derivative of the difference in light intensities detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path, refers to the partial derivative of the difference in light intensities detected by the first light source receiving sensor and the third light source receiving sensor with respect to the optical path, refers to the partial derivative of the difference in light intensities detected by the second light source receiving sensor and the third light source receiving sensor with respect to the optical path. Three values will be calculated respectively, which are , and . When the three PDs receive light sources, in addition to the influence of the animal's own blood oxygen, environmental light interference is also involved. In the present invention, PD1 and PD2 are used as tissue oxygen acquisition receivers, and PD3 is used as an environmental light receiver, that is the data obtained by the tissue oxygen sensor is ; 24 the environmental light interference is ; 25 Therefore, the finally obtained oxygen saturation with environmental light cancellation is

[0062] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0063] It should be understood that those of ordinary skill in the art can make improvements or transformations according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A near-infrared tissue oxygen monitoring system, characterized in that: It includes a near-infrared blood oxygen probe, a circuit acquisition board, and a host computer system. The near-infrared blood oxygen probe is connected to the circuit acquisition board, and the circuit acquisition board is connected to the host computer system; The near-infrared blood oxygen probe includes two light source emission devices and three light source receiving sensors connected to the circuit acquisition board. The two light source emission devices are used to emit lights of different wavelengths respectively, and the light source receiving sensors are used for receiving and transmitting optical signals; The host computer system is used to solve the current tissue oxygen value according to the received optoelectronic signals.

2. The near-infrared tissue oxygen monitoring system according to claim 1, wherein: The lights of different wavelengths emitted by the two light source emission devices are red light and infrared light respectively; The wavelengths of the red light and the infrared light are respectively in the range of 620 - 750 nm and 800 - 900 nm.

3. The near-infrared tissue oxygen monitoring system according to claim 1, characterized in that: The acquisition circuit board includes a core processing module, and a clock crystal oscillator, a radio frequency antenna, a battery, and a power management chip connected to the core processing module.

4. The near-infrared tissue oxygen monitoring system according to claim 1, characterized in that: The 3 light source receiving sensors are evenly distributed at equal intervals along a straight line, and the distance between adjacent light source receiving sensors is 5 - 10 mm.

5. The near-infrared tissue oxygen monitoring system according to claim 1, wherein: The light source emission device is a light-emitting diode, and the light source receiving sensor is a photoelectric sensor.

6. A method for monitoring tissue oxygen using the near-infrared tissue oxygen monitoring system as described in claim 1, characterized in that: It includes the following steps: Step 1, the two light source emission devices emit two lights of different wavelengths; Step 2, the two emitted lights are absorbed and scattered by biological tissues and then received by the light source receiving sensors. Two of the three light source receiving sensors are used as tissue oxygen acquisition receivers, and the remaining one is used as an ambient light receiver; Step 3, the light source receiving sensors convert the collected optical signals into electrical signals, and the corresponding data signals are transmitted to the host computer system through the circuit acquisition board; Step 4, the host computer system calculates the tissue oxygen saturation of the biological counteracting ambient light through the data signals collected by the three light source receiving sensors.

7. The method for monitoring tissue oxygen according to claim 6, wherein: The lights of different wavelengths emitted by the two light source emission devices are the first wavelength light and the second wavelength light respectively, and the three light source receiving sensors are the first light source receiving sensor, the second light source receiving sensor, and the third light source receiving sensor respectively; In the said Step 4, the specific process of the host computer system calculating the tissue oxygen saturation of the biological counteracting ambient light through the data signals collected by the three light source receiving sensors is: Obtain the first sensor oxygen saturation value based on the light intensities of the first wavelength light and the second wavelength light detected by the first light source receiving sensor and the second light source receiving sensor ; Obtain the oxygen saturation value of the second sensor based on the light intensities of the first wavelength light and the second wavelength light detected by the first light source receiving sensor and the ambient light intensity detected by the third light source receiving sensor ; Obtain the oxygen saturation value of the third sensor based on the light intensity of the first wavelength light and the light intensity of the second wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor ; Based on the oxygen saturation value of the first sensor Obtain the tissue oxygen sensor value , based on the oxygen saturation value of the second sensor and the oxygen saturation value of the third sensor Obtain the environmental interference value ; Based on the values of the tissue oxygen sensor and the environmental interference value calculate the tissue oxygen saturation at which the organism cancels out the ambient light.

8. The method for monitoring tissue oxygen according to claim 7, wherein: Obtain the first sensor oxygen saturation value based on the light intensities of the light with the first wavelength and the light with the second wavelength detected by the first light source receiving sensor and the second light source receiving sensor The specific process is as follows: Take the partial derivative of the difference in the light intensities of the first-wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path and take the partial derivative of the difference in the light intensities of the second-wavelength light detected by the first light source receiving sensor and the second light source receiving sensor with respect to the optical path ; According to and calculate the oxygen saturation value of the first sensor .

9. The method for monitoring tissue oxygen according to claim 7, characterized in that: Obtain the oxygen saturation value of the second sensor based on the light intensity of the first wavelength light detected by the first light source receiving sensor, the light intensity of the second wavelength light, and the light intensity of the ambient light detected by the third light source receiving sensor The specific process is as follows: Take the partial derivative of the difference between the light intensity of the first wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path and take the partial derivative of the difference between the light intensity of the second wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path ; According to and calculate the oxygen saturation value based on the second sensor .

10. The method for monitoring tissue oxygen according to claim 7, characterized in that: Obtain the oxygen saturation value of the third sensor based on the light intensity of the first-wavelength light and the light intensity of the second-wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor The specific process is as follows: Take the partial derivative of the difference between the light intensity of the first-wavelength light detected by the second light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path and take the partial derivative of the difference between the light intensity of the second-wavelength light detected by the first light source receiving sensor and the light intensity of the ambient light detected by the third light source receiving sensor with respect to the optical path ; According to and calculate the oxygen saturation based on the third sensor .

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