An implantable blood drug concentration real-time monitoring device for surgical anesthesia

Abstract

The present application belongs to the field of medical devices, and particularly relates to an implantable blood drug concentration real-time monitoring device for surgical anesthesia, aiming at solving the problems of existing blood gas monitoring, such as great trauma, non-continuity, easy electromagnetic interference and poor stability. The device comprises a fiber-optic indwelling needle assembly, a multi-parameter fiber-optic sensing probe, an optical signal modulation and demodulation unit, a reference light path compensation module, a cross-sensitivity correction unit and a central processing terminal, realizes in-situ synchronous monitoring of oxygen partial pressure, carbon dioxide partial pressure, pH value, temperature and flow rate through an all-fiber metal-free structure, and has the advantages of anti-electromagnetic interference, long-term stability, frequent calibration-free and suitability for MRI environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical devices, and particularly relates to an implantable blood drug concentration real-time monitoring device for surgical anesthesia. BACKGROUND

[0002] In the field of intensive care, anesthesia and critical patient management, real-time, continuous and minimally invasive monitoring of blood gas parameters (such as pH, pO2, pCO2, etc.) has crucial clinical significance for timely assessment of patient oxygenation status, acid-base balance and ventilation function. Traditional blood gas monitoring relies on intermittent arterial blood sampling combined with an external analyzer, which can provide accurate data, but due to the strong invasiveness of the operation, non-continuous monitoring, delayed results and the need for repeated puncture, it is difficult to meet the needs of precise capture and immediate intervention of dynamic physiological changes. In recent years, continuous blood gas monitoring technology has gradually developed, aiming to achieve in-situ and real-time data acquisition through implantable sensors, thereby improving clinical decision-making efficiency and patient comfort.

[0003] Among them, the continuous blood gas monitoring system based on electrochemical principle has become the mainstream technology path. This kind of system usually integrates a miniature electrochemical sensor in an arterial indwelling catheter, and transmits the electrical signal to the external host through a metal wire for processing and display. Its core goal is to reduce the frequency of blood sampling while maintaining the ability to continuously track key blood gas indicators. However, this technical route faces multiple bottlenecks in actual application: the sensor is easily contaminated by protein and cell components in the blood, leading to degradation of the sensitive membrane performance and signal drift, which requires frequent external blood sample calibration, weakening the clinical value of continuous monitoring; the metal wire is not only susceptible to electromagnetic interference (especially in strong electromagnetic environments such as MRI), but also has potential safety risks of breakage or encapsulation failure; in addition, the single catheter has limited ability to integrate multiple parameter sensors, making it difficult to monitor multiple blood gas indicators simultaneously, and the sensor has poor stability in the body, with a service life usually not exceeding 72 hours.

[0004] Therefore, the existing technology is trapped in the fundamental contradiction between minimally invasive, continuous, stable and multi-parameter compatibility. On the one hand, intermittent blood sampling cannot meet the real-time dynamic monitoring needs; on the other hand, the existing continuous monitoring system has inherent defects in materials, structure and sensing mechanism, making it difficult to balance long-term stability, anti-interference ability and clinical safety. Especially in the critical scene that needs long-term monitoring, sensor drift, calibration dependence and electromagnetic sensitivity significantly restrict its reliability and promotion value. Therefore, there is an urgent need for a new type of blood gas monitoring device that can achieve real-time continuous monitoring with high stability, anti-interference, frequent calibration-free and support for multi-parameter synchronous detection under the premise of true minimally invasive. SUMMARY

[0005] The present application aims to provide an implantable blood drug concentration real-time monitoring device for surgical anesthesia, so as to solve the technical defects of high trauma, non-continuous monitoring, easy to be interfered by electromagnetic interference, poor sensor stability, short service life, frequent calibration and limited multi-parameter integration capability in the existing blood gas monitoring technology.

[0006] The technical scheme of the present application is an implantable blood drug concentration real-time monitoring device for surgical anesthesia, comprising: a fiber indwelling needle assembly, a multi-parameter fiber sensing probe, an optical signal modulation and demodulation unit, a reference light path compensation module, a temperature and pressure cross-sensitivity correction unit, and a central processing and display terminal; wherein the fiber indwelling needle assembly is a hollow catheter structure made of medical grade polymer material, which is embedded with a single or multiple special optical fibers, and the special optical fibers are integrated with multiple distributed fiber sensing probes in the catheter tip area; the multi-parameter fiber sensing probe is based on the physical response mechanism of fluorescence lifetime, absorption spectrum or fiber Bragg grating to in-situ sense the partial pressure of oxygen, the partial pressure of carbon dioxide, the pH value, the temperature and the flow rate in the blood; the optical signal modulation and demodulation unit emits excitation light pulses of specific wavelength and pulse width to the special optical fiber, and receives the response light signals reflected or emitted by each sensing probe, and separates the light signal components corresponding to each parameter through time resolution or wavelength resolution technology; the reference light path compensation module is arranged in the non-implanted area near the proximal end of the fiber indwelling needle assembly, which is used to provide a reference light signal unaffected by the blood environment to eliminate the system error caused by light source fluctuation, fiber bending loss and connector aging; the temperature and pressure cross-sensitivity correction unit performs multi-dimensional decoupling operation on the original optical signal based on the pre-calibrated cross-sensitivity matrix, and outputs independent and accurate blood gas parameter values; the central processing and display terminal receives the corrected blood gas parameter data, performs real-time trend analysis, abnormal early warning and visual presentation, and supports data docking with the hospital information system.

[0007] Further, the multi-parameter fiber sensing probe adopts a modular microstructure design, and each probe is distributed along the fiber axial direction with a spacing not less than 5mm to avoid optical crosstalk; each probe contains a microcavity structure, and the inner wall of the microcavity is coated with a fluorescent or absorption sensitive material which has selective response to specific blood gas components; wherein the oxygen partial pressure probe adopts a sol-gel film doped with ruthenium complex, and the fluorescence lifetime of the film exponentially decays with the increase of oxygen partial pressure; the carbon dioxide partial pressure probe adopts a polymer film in which pH sensitive dye and carbonic anhydrase are co-immobilized, and the carbon dioxide partial pressure is indirectly reflected by detecting the pH change in the film; the pH probe adopts a dual-wavelength ratio type fluorescent dye film, and the intensity ratio of the two emission peaks has a monotonic function relationship with the hydrogen ion concentration; the temperature probe adopts a fiber Bragg grating, and the reflection wavelength linearly drifts with temperature; the flow rate probe adopts a microstructure based on the thermo-optic effect, and the blood flow velocity is calculated by measuring the local thermal disturbance recovery time.

[0008] Further, the optical signal modulation and demodulation unit comprises a pulsed laser source, a wavelength division multiplexer, an array of photodetectors and a high-speed digital signal processor; the pulsed laser source outputs excitation light with wavelengths of 405 nm, 470 nm and 532 nm, corresponding to the excitation requirements of different sensing probes; the wavelength division multiplexer couples the multi-wavelength excitation light into the same special optical fiber, and separates the returned response light according to wavelengths to corresponding photodetectors; the high-speed digital signal processor performs time-gated acquisition, records the fluorescence decay curve only within a preset time window, so as to suppress the interference of background scattered light, and calculates the fluorescence lifetime through a least square fitting algorithm.

[0009] Further, the reference light path compensation module comprises a reference optical fiber manufactured in the same batch as the implanted optical fiber, and a fixed mirror is arranged at the end of the reference optical fiber to form a stable Fabry-Perot interference structure; the reference light path and the main sensing light path share the same light source and detection channel, and the reference signal and the sensing signal are alternately acquired through time division multiplexing, so as to realize real-time compensation for system gain drift.

[0010] Further, the temperature and pressure cross-sensitivity correction unit is built-in a multi-dimensional correction model, which is constructed based on laboratory calibration data and covers the cross-response coefficients of oxygen partial pressure, carbon dioxide partial pressure and pH value to temperature and hydrostatic pressure; the correction process adopts matrix inversion to map the original multi-wavelength or multi-lifetime measurement values to an independent physiological parameter space without cross interference.

[0011] Further, the central processing and display terminal is configured with an adaptive baseline drift suppression algorithm, which continuously monitors the historical trend of each parameter, and automatically triggers a non-invasive calibration mode when detecting that the slow drift exceeds a preset threshold; the non-invasive calibration mode dynamically corrects the optical fiber sensing data by fusing auxiliary physiological signals such as patient's body surface pulse blood oxygen saturation, respiratory rate and body temperature, without the need of extracting blood samples.

[0012] Further, the optical fiber indwelling needle assembly has an outer diameter of not more than 1.2 mm and a length of 25 to 50 mm, and is suitable for conventional puncture and placement of radial artery, femoral artery or brachial artery; the special optical fiber is a photonic crystal fiber or a fluorine-doped quartz optical fiber which is resistant to bending loss, and the cladding structure is treated by a biocompatible coating to ensure the safety and stability of long-term indwelling.

[0013] Further, the entire device is completely free of metal in physical structure, and all signal transmission is completed through optical signals, so that the device can be safely operated in a magnetic resonance imaging environment and is not interfered by radio frequency, microwave or power frequency electromagnetic fields.

[0014] Compared with the prior art, the application has the following advantages and positive effects:

[0015] This invention, by employing an all-fiber sensing architecture, completely eliminates the metal wires and electrode structures required by traditional electrochemical sensors, fundamentally eliminating electromagnetic interference problems and enabling the system to operate safely and continuously in strong electromagnetic environments such as MRI. The multi-parameter fiber optic sensing probe, based on optical physics mechanisms rather than biochemical reactions, avoids signal drift caused by enzyme inactivation and protein contamination, significantly improving the long-term stability and lifespan of the sensor, enabling continuous monitoring for over 72 hours without external calibration. Through a distributed microcavity probe design and wavelength-time dual-resolution technology, it achieves simultaneous in-situ detection of multiple parameters, including oxygen partial pressure, carbon dioxide partial pressure, pH value, temperature, and blood flow velocity, breaking through the limitations of traditional catheter integration capabilities. The synergistic effect of the reference optical path compensation module and the cross-sensitivity correction unit effectively suppresses light source fluctuations, fiber loss, and environmental cross-interference, ensuring measurement accuracy. The non-invasive adaptive calibration mechanism further reduces reliance on manual intervention, truly achieving minimally invasive, continuous, real-time, and highly reliable blood gas monitoring, providing a novel technical means for intensive care, surgical anesthesia, and critical care. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall technical solution architecture of the present invention;

[0017] Figure 2 This is a schematic diagram of the core principle framework of the collaborative operation of the multi-parameter fiber optic sensing probe and cross-sensitive correction in this invention. Detailed Implementation

[0018] Example 1

[0019] Please refer to Figure 1 and Figure 2 This invention provides an implantable real-time blood drug concentration monitoring device for surgical anesthesia. Its core objective is to overcome the inherent technical bottlenecks of existing blood gas monitoring technologies, such as invasiveness, discontinuity, sensitivity to electromagnetic interference, insufficient sensor stability, short lifespan, high calibration frequency, and limited integration of multiple parameters. By employing an all-fiber optic sensing architecture, it achieves real-time, continuous, and minimally invasive monitoring of key physiological parameters in the blood. This device precisely integrates fiber optic sensing technology with the structure of a medical indwelling needle, aiming to provide a stable, accurate, and electromagnetically immune innovative monitoring method for intensive care, surgical anesthesia, and critical care.

[0020] The device comprises a fiber optic indwelling needle assembly, a multi-parameter fiber optic sensing probe, an optical signal modulation and demodulation unit, a reference optical path compensation module, a temperature and pressure cross-sensitivity correction unit, and a central processing and display terminal. The overall operation begins with the fiber optic indwelling needle assembly being implanted into a blood vessel via a minimally invasive procedure. Its embedded multi-parameter fiber optic sensing probe directly contacts the blood, sensing physiological parameters such as oxygen partial pressure, carbon dioxide partial pressure, pH value, temperature, and blood flow velocity in situ. The sensing probe converts the sensed physiological information into physical changes in optical signals. These optical signals are then received and processed by the optical signal modulation and demodulation unit, converting them into electrical signals using precise modulation and demodulation techniques. To ensure measurement accuracy, the reference optical path compensation module eliminates system errors introduced by light source fluctuations and fiber optic transmission losses in real time. Simultaneously, the temperature and pressure cross-sensitivity correction unit performs multi-dimensional decoupling of the original optical signals, removing interference from environmental factors on the measurement results. Finally, the calibrated and accurate blood gas parameter data is transmitted to the central processing and display terminal for real-time trend analysis, anomaly warning, and visualization, and can seamlessly interface with the hospital information system. The entire device contains no metal parts at the physical level, and all signal transmission relies on optical signals, thus ensuring the safety and signal integrity of the device in strong electromagnetic environments such as magnetic resonance imaging.

[0021] The fiber optic indwelling needle assembly is the minimally invasive interventional part of the device that directly contacts the patient's blood vessels, and its design and manufacturing adhere to stringent medical-grade standards. This assembly uses a hollow catheter structure made of medical-grade polymer materials, specifically polyurethane, polyethylene, polytetrafluoroethylene, or their biocompatible derivatives. These materials possess excellent bioinertness, a low coefficient of friction, superior flexibility, and good anticoagulant properties. The outer diameter of the catheter is strictly controlled to no more than 1.2 mm to minimize puncture trauma; its length can be selected between 25 mm and 50 mm to accommodate routine punctures into different vessels such as the radial artery, femoral artery, or brachial artery. The catheter tip undergoes precision machining, such as bevel cutting, blunt grinding, and hydrophilic coating, to reduce puncture resistance, minimize damage to the vessel wall, and promote post-implantation blood compatibility. The hollow catheter forms a micro-cavity for the safe embedding of one or more specialized optical fibers. During manufacturing, specialized optical fibers are precisely positioned and embedded in the inner wall of the catheter along its axis, either parallel or spirally, using medical-grade adhesives, micro-clamps, or thermofusion fixation techniques. This ensures the fiber is unaffected by mechanical stresses such as bending, stretching, or shearing during implantation and use. The fiber's cladding undergoes special biocompatible coating treatments, such as polyimide, fluoropolymers, or heparin-containing hydrophilic coatings, to further enhance its anticoagulant properties and long-term placement safety, effectively reducing the risk of thrombosis and biological infection, and ensuring stability and safety during its presence in the body. The catheter tip region is an integrated area for multiple distributed optical fiber sensing probes. These probes are directly integrated into the end or side of the specialized optical fiber using microstructure fabrication techniques, such as femtosecond laser writing or chemical etching, ensuring direct contact with blood and enabling in-situ sensing of local blood gas parameters.

[0022] The multi-parameter fiber optic sensing probe is the core component of the device for sensing blood physiological information. It integrates a fiber sensor whose surface is modified with molecularly imprinted polymers to specifically recognize target anesthetic drugs. Employing a modular microstructure design, the probes are precisely spaced along the axis of a special optical fiber, maintaining a minimum distance of 5 mm between each probe. This spacing design is crucial, effectively preventing optical crosstalk or signal interference between different probes and ensuring that each probe performs parameter measurements independently and accurately. Each probe contains a microcavity structure, whose geometry can be micrometer-scale spherical, cylindrical, or conical, formed on the end or side of the optical fiber using precision processes such as fused taper, chemical etching, or micro / nano imprinting. The inner wall of the microcavity is uniformly coated with a fluorescent or absorbent material that exhibits highly selective response to specific blood gas components. Coating processes include dip coating, spray coating, or electrodeposition to ensure uniform film thickness, strong adhesion, and high stability.

[0023] Fiber optic sensing unit: The end of the fiber optic cable is equipped with a sensing point and is coated with a fluorescent material (such as HPTS, ruthenium complex, etc.) that is sensitive to pH, pO2, and pCO2.

[0024] (1) Microfiber: 1-3 fibers, each corresponding to a sensing parameter (e.g., fiber 1 measures pH, fiber 2 measures pO2, fiber 3 measures pCO2).

[0025] Type: Multimode fiber to ensure sufficient light throughput.

[0026] Path: Starting from the sensing point near the tip of the needle, it passes through the pre-embedded channel within the entire needle and tubing wall, and finally converges at the optical interface at the tail of the needle hub.

[0027] (2) Sensing Spot:

[0028] Location: Located on the side wall of the needle tube (to avoid tip blockage), the fiber core is exposed by forming microgrooves or removing part of the cladding through laser processing or chemical etching.

[0029] Coating: Fluorescent dyes sensitive to specific parameters are coated onto the exposed fiber core.

[0030] 3. Stability enhancement layer: Based on AChE@ZIF packaging technology.

[0031] (1) Material: ZIF-8 (zeolite imidazole ester framework-8), which is composed of zinc ions and 2-methylimidazole.

[0032] (2) Process: A dense and uniform ZIF-8 crystal film is grown on the sensing point coated with fluorescent dye by biomimetic mineralization method.

[0033] (3) Functions: ① Physical protection: It firmly "locks" the fragile fluorescent dye molecules in the ZIF-8 lattice, preventing them from falling off or being lost during use and blood flushing.

[0034] ② Chemical barrier: Prevents large molecules such as proteins, lipids, and cells in the blood from directly contacting and contaminating the sensor point, while allowing small molecules such as H ions, O2, and CO2 to pass freely, ensuring the long-term stability of the signal.

[0035] Specifically:

[0036] For the oxygen partial pressure probe, the sensitive material is a ruthenium complex-doped sol-gel membrane. The ruthenium complex is typically tris(2,2'-bipyridine)ruthenium(II) complex, a highly efficient oxygen-sensitive fluorescent probe. The sol-gel matrix is ​​generally prepared from silica or titanium dioxide precursors through hydrolysis and condensation reactions, forming a porous structure that allows oxygen molecules to diffuse freely around the ruthenium complex. The probe operates based on the fluorescence quenching effect, where the fluorescence lifetime of the ruthenium complex decreases exponentially with increasing oxygen partial pressure—a dynamic quenching mechanism. This probe exhibits excellent response time, a stable linear range, and sensitivity to physiological oxygen partial pressure, ensuring accurate measurements within clinical limits.

[0037] For carbon dioxide partial pressure probes, the sensitive material is a polymer membrane co-immobilized with a pH-sensitive dye and carbonic anhydrase. The pH-sensitive dye, such as hydroxypyranamine or a fluorescein derivative, exhibits fluorescence properties affected by the ambient pH. Carbonic anhydrase is co-immobilized in a polymer matrix such as polyacrylamide or hydrogel. The enzyme's role is to accelerate the reaction of carbon dioxide with water to form carbonic acid, which then dissociates into hydrogen ions, leading to a change in the pH within the membrane. The system indirectly reflects the partial pressure of carbon dioxide in the blood by detecting changes in the membrane's pH. The polymer membrane is prepared using cross-linking or encapsulation techniques to ensure enzyme activity and membrane stability. A clear chemical equilibrium exists between carbon dioxide partial pressure and hydrogen ion concentration, allowing the probe to accurately calculate carbon dioxide partial pressure based on pH changes.

[0038] The pH probe employs a dual-wavelength ratio fluorescent dye membrane. Commonly used dyes include SNARF or HPTS, whose relative intensities of two emission peaks change under different pH conditions. The system measures the ratio of these two emission peak intensities, which is monotonically related to the hydrogen ion concentration. The dual-wavelength ratio measurement method has self-reference characteristics, effectively suppressing the effects of light source fluctuations, dye concentration variations, and fiber optic transmission losses on the measurement results, thereby improving the accuracy and stability of pH measurements. The probe can accurately measure the physiological pH range of 6.8 to 7.8 and has a rapid response capability.

[0039] The core of the temperature probe utilizes fiber Bragg grating technology. The fiber Bragg grating is inscribed into the core of a special optical fiber using ultraviolet laser writing or femtosecond laser writing processes. The grating's reflected wavelength exhibits a linear drift response to temperature, with its sensitivity typically measured in picometers per degree Celsius. By precisely measuring the wavelength shift of the grating's reflection peak, the system can accurately sense local blood temperature. Fiber Bragg grating probes offer advantages such as small size, high precision, and resistance to electromagnetic interference, and employ a special packaging method to ensure long-term stability in bodily fluid environments.

[0040] The flow velocity probe employs a thermo-optical effect microstructure. This microstructure includes a miniature heater and a miniature temperature sensor, integrated onto the surface of an optical fiber using precision machining techniques. During operation, the miniature heater momentarily and weakly heats the local blood flow, while the miniature temperature sensor monitors the diffusion and dissipation of thermal disturbances within the blood. By measuring the time required for the local thermal disturbance to return to ambient temperature, and combining this with the principles of thermal diffusion and convective heat transfer, the system can accurately calculate the local blood flow velocity. This probe exhibits a fast response time, capable of reflecting the range of changes in blood flow velocity in real time, providing crucial data for circulatory monitoring.

[0041] The optical signal modulation and demodulation unit is responsible for emitting excitation light to the multi-parameter fiber optic sensing probe and receiving and processing the response optical signal returned by the probe. It is the hub for realizing photoelectric conversion and signal processing. The core components of this unit include a pulsed laser source, a wavelength division multiplexer, a photodetector array, and a high-speed digital signal processor.

[0042] Pulsed laser sources typically employ high-performance semiconductor or solid-state lasers, capable of outputting excitation light at specific wavelengths such as 405 nm, 470 nm, and 532 nm. These wavelengths are carefully selected based on the optimal excitation spectra of different fluorescent dyes or sensitive materials to ensure maximum excitation efficiency. The laser source features nanosecond-level pulse widths and adjustable pulse repetition frequencies, ensuring effective differentiation between excitation light and fluorescence signals in time-gated acquisition mode. The power and wavelength stability of the laser are rigorously maintained through precise temperature and current control mechanisms to minimize the impact of light source fluctuations on measurement accuracy.

[0043] A wavelength division multiplexer (WDM) precisely couples multi-wavelength excitation light emitted from a pulsed laser source into the same specialized optical fiber and transmits it to the sensing probe at the front end of the fiber optic insertion needle assembly. Simultaneously, the WDM also separates the response light (including fluorescence signals and reflected light) returned from each sensing probe according to their wavelength differences and guides the separated optical signals to the corresponding photodetectors. The WDM employs thin-film filter or grating-type devices, featuring low insertion loss and high isolation, ensuring signal transmission efficiency and the purity of wavelength separation.

[0044] The photodetector array consists of multiple high-speed, high-sensitivity photodiodes, such as avalanche photodiodes or PIN photodiodes, each corresponding to a specific wavelength range of response optical signal. The detectors possess fast response time, high quantum efficiency, and low noise characteristics, enabling them to accurately convert weak optical signals into electrical signals. The array configuration is strictly matched to the wavelength division multiplexer's demultiplexing channels, ensuring that the signal for each parameter can be captured independently and effectively.

[0045] A high-speed digital signal processor (DSP) is the "brain" of the system for signal processing, typically employing a high-performance field-programmable gate array (FPGA) or DSP chip. The processor is responsible for performing time-gated acquisition tasks. In time-gated acquisition mode, the processor records the fluorescence decay curve only during the period when the fluorescence signal is strongest and background scattering interference is minimal, through precise synchronous triggering and a preset acquisition time window. This mechanism significantly suppresses interference caused by excitation light, background light, and fiber Rayleigh scattering, thereby greatly improving the signal-to-noise ratio and measurement accuracy. The acquired fluorescence decay data is then processed using a least-squares fitting algorithm, specifically applying a single-exponential or double-exponential decay model to iteratively calculate the fluorescence lifetime. The fitting algorithm, by defining a precise fitting function and convergence criteria, ensures that the calculated fluorescence lifetime value accurately reflects the oxygen partial pressure information. The processor is also responsible for digitizing, filtering, and performing preliminary calculations on the raw electrical signals of other parameters (such as pH ratio, fiber Bragg grating wavelength drift, and thermo-optical recovery time), providing data input for subsequent cross-sensitivity correction.

[0046] The reference optical path compensation module is designed to eliminate system gain drift caused by factors such as light source fluctuations, fiber bending loss, connector aging, and temperature drift, thereby ensuring the stability and measurement accuracy of the sensing signal. This module is located in the proximal non-implanted area of ​​the fiber optic insertion pin assembly, connected in parallel with the main sensing optical path. Its core component includes a section of reference fiber manufactured in the same batch as the implanted special fiber. This ensures extremely high consistency between the reference fiber and the sensing fiber in terms of material properties, coefficient of thermal expansion, and refractive index, enabling accurate simulation of the sensing optical path's behavior under environmental changes. A fixed reflector is precisely mounted at the end of the reference fiber. The reflector is typically a dielectric film reflector or a metal reflector, possessing high reflectivity and excellent stability. This reflector and the end face of the reference fiber together form a stable Fabry-Perot interference structure, whose reflection or transmission spectrum exhibits a predictable response to light source fluctuations and fiber loss.

[0047] The reference optical path and the main sensing optical path share the same pulsed laser source and photoelectric detection channel, which avoids additional errors introduced by differences in the characteristics of different light sources or detectors. The device implements a time-division multiplexing acquisition method through a high-speed optical switch or electro-optic modulator. Within a preset acquisition period, the device alternately guides the light signal emitted by the light source to the main sensing optical path and the reference optical path, and receives the light signals returned from them respectively. For example, in a 20-millisecond acquisition period, 10 milliseconds are used to acquire the sensing signal, and the other 10 milliseconds are used to acquire the reference signal. This time-division multiplexing strategy requires strict time synchronization and data management mechanisms to ensure the accuracy of each switch.

[0048] During the data processing phase, the high-speed digital signal processor receives raw optical signal data from the main sensing optical path and the reference optical path. The signal returned from the reference optical path serves as a benchmark, reflecting the current light source power, fiber transmission loss, and connector status. By performing real-time comparison or proportional correction, differential correction, and other algorithmic processing on the sensing signal received by the main sensing optical path and the synchronously acquired reference signal, the system can accurately identify and subtract error components caused by system gain drift. For example, if the light source power decreases by 10%, the reference signal strength will decrease by 10% accordingly. When the sensing signal also shows the same 10% decrease, the device will treat it as a systematic error and compensate for it, rather than incorrectly interpreting it as a change in physiological parameters. This mechanism ensures that even when the fiber is slightly bent, the light source ages, or the ambient temperature changes cause minor drift in fiber performance, the final output blood gas parameter values ​​remain highly accurate and stable.

[0049] The temperature and pressure cross-sensitivity correction unit is a crucial component ensuring the measurement accuracy of this device. Its function is to eliminate cross-interference caused by ambient temperature and intravascular hydrostatic pressure on blood gas parameter measurements. Because the sensitive materials in the multi-parameter fiber optic sensing probe are not only sensitive to the target parameter but also affected by temperature and pressure, precise decoupling is essential. This unit incorporates a multi-dimensional correction model built upon extensive laboratory calibration data, covering detailed cross-response coefficients of oxygen partial pressure, carbon dioxide partial pressure, and pH value to temperature and hydrostatic pressure.

[0050] Laboratory calibration is a highly controlled and systematic process. Within a specially designed temperature-controlled chamber and pressure chamber, the response characteristics of each sensor probe are systematically measured under different temperature (e.g., 25°C to 45°C, in 0.5°C increments) and pressure (e.g., 0 kPa to 20 kPa, in 0.5 kPa increments) conditions by precisely controlling the concentration of a standard gas mixture (oxygen, carbon dioxide), the pH buffer solution, and the simulated intravascular hydrostatic pressure. The collected data includes optical measurements such as raw fluorescence lifetime, fluorescence intensity ratio, and grating reflection wavelength, as well as the corresponding true values ​​of actual physiological parameters. This data is used to train or build calibration models, such as using polynomial fitting, multiple linear regression, or more complex neural network models to capture complex nonlinear cross-sensitivity relationships. The cross-response coefficients are precisely quantified; for example, the fluorescence lifetime of a certain oxygen partial pressure sensitive membrane may decrease by 0.1 nanoseconds for every 1°C increase in temperature or change by 0.05 nanoseconds for every 1 kPa increase in pressure.

[0051] The calibration process employs matrix inversion. First, the raw multi-wavelength intensity, multi-fluorescence lifetime, or wavelength drift measurements are organized into an input vector. This vector contains all the uncalibrated raw data received from the optical signal modulation and demodulation unit. Internally, a cross-sensitivity matrix is ​​established within the calibration model, its elements consisting of pre-calibrated cross-response coefficients. This matrix describes how each raw measurement is affected by the combined influence of the target physiological parameter and cross-interference parameters (temperature, pressure). By performing matrix inversion—multiplying the raw measurement vector by the inverse of the cross-sensitivity matrix—the device can map the raw multi-wavelength or multi-lifetime measurements to an independent physiological parameter space free from cross-interference. For example, a 3x3 cross-sensitivity matrix might contain sensitivity coefficients for oxygen partial pressure to temperature, carbon dioxide partial pressure to temperature, and pH to temperature, as well as their sensitivity to pressure. The goal of the inversion is to decouple the actually measured optical quantities into independent oxygen partial pressure, carbon dioxide partial pressure, and pH values, so that these output values ​​reflect only their own physiological state, unaffected by secondary effects of temperature and pressure. This method ensures that the device can still output independent and accurate blood gas parameter values ​​even when the patient's body temperature fluctuates or blood pressure changes, greatly improving the reliability of clinical monitoring.

[0052] The central processing and display terminal serves as the intelligent decision-making and human-machine interface for the entire device, responsible for receiving, processing, analyzing, and presenting calibrated blood gas parameter data. This terminal is equipped with a high-performance microcontroller or embedded processor, a large-capacity memory for storing historical data, and a high-resolution display for visualization.

[0053] The terminal receives precisely calibrated blood gas parameter data transmitted from the temperature and pressure cross-sensitivity correction unit. The data is transmitted via a high-speed serial interface (such as SPI, I2C or UART) or Ethernet interface, and is encapsulated in a standardized floating-point or fixed-point format, following a customized data transmission protocol to ensure data integrity and real-time performance.

[0054] The processor performs real-time trend analysis on the received data. This function is achieved by applying algorithms such as moving average, exponential smoothing, or Kalman filtering to filter out measurement noise and smooth data curves, thereby clearly showing the trend of blood gas parameters over time. Trend charts can be dynamically plotted and traced on the display screen at different time scales such as minutes, hours, and days, allowing medical staff to fully understand the patient's physiological status.

[0055] The system has a built-in anomaly warning mechanism. Medical staff can preset high and low alarm thresholds for various blood gas parameters, such as triggering an alarm when the oxygen partial pressure is below 60 mmHg or above 100 mmHg. The warning logic supports single-parameter over-limit alarms as well as multi-parameter linked alarms, such as triggering a higher-level warning when the oxygen partial pressure decreases while the carbon dioxide partial pressure increases. Alarm methods include audible and visual indicators, on-screen pop-up prompts, and remote notifications sent to mobile devices or the central monitoring station via wireless network, ensuring that abnormal situations can be detected and handled promptly.

[0056] The visualization function provides an intuitive and clear user interface, displaying blood gas parameters in various forms such as numerical displays, line graphs, bar charts, and chromatograms. The data refresh rate can reach 10 times per second, ensuring real-time performance. The terminal also has a historical data review function, allowing medical staff to query and analyze the patient's blood gas changes over the past few hours, days, or even longer.

[0057] To achieve seamless integration with the existing healthcare information ecosystem, the central processing and display terminal supports data interface with Hospital Information Systems (HIS), Electronic Medical Record Systems (EMR), or Picture Archiving and Communication Systems (PACS). This is accomplished through interface protocols compliant with industry standards such as HL7, DICOM, or MQTT. All transmitted data is encrypted and authenticated to ensure patient privacy and data security.

[0058] The terminal is also equipped with an adaptive baseline drift suppression algorithm. This algorithm continuously monitors the long-term historical trends of various blood gas parameters, such as calculating the average data from the past hour every 15 minutes and comparing it with the baseline over a longer time scale (e.g., the past 12 or 24 hours). When a slow drift of a parameter is detected to exceed a preset threshold (e.g., the average oxygen partial pressure deviates from the baseline by more than 5% for two consecutive hours), the algorithm automatically triggers a non-invasive calibration mode. The preset threshold is determined based on statistical methods and a large amount of clinical experience data, aiming to distinguish between physiological fluctuations and sensor drift.

[0059] The non-invasive calibration mode is a key innovation of this system, aiming to dynamically correct the offset of fiber optic sensor data without drawing blood samples. This mode achieves this by fusing auxiliary physiological signals such as the patient's surface pulse oximetry, respiratory rate, and body temperature. For example, arterial oxygen saturation (SpO2) is continuously acquired using a finger-clip pulse oximeter, respiratory rate is obtained through respiratory waveform analysis from a respiratory sensor or ECG monitor, and body temperature is acquired using a temperature sensor. These auxiliary physiological signals are input into the calibration algorithm, which establishes a multi-input-single-output mapping model. This model is pre-trained with a large amount of clinical data, learning the correlation and offset patterns between fiber optic sensor data and auxiliary physiological signals under different physiological states. When calibration is triggered, the algorithm dynamically calculates the correction offset of the fiber optic sensor data based on the currently fused auxiliary physiological signals and makes real-time corrections to oxygen partial pressure, carbon dioxide partial pressure, and pH value. This dynamic offset correction mechanism can effectively maintain the sensor's measurement accuracy over continuous monitoring periods of 72 hours or even longer, significantly reducing the need for manual calibration and avoiding the additional trauma and infection risks to patients caused by repeated blood sample extraction.

[0060] The entire device features a completely metal-free design in its physical structure. All core components and signal transmission paths contain no metal materials, and signal transmission is entirely achieved through optical signals. The special optical fiber itself is made of high-purity quartz or special glass, and the sensing probe's sensitive material is an organic or inorganic non-metallic polymer. This design fundamentally eliminates the electromagnetic compatibility issues that may arise from metal electrodes and wires in traditional electrochemical sensors. Therefore, this device can operate safely in strong magnetic field environments, such as inside or near magnetic resonance imaging (MRI) equipment, without producing artifacts in MRI images or causing localized heating effects due to magnetic field induction, ensuring patient safety. Simultaneously, the system is naturally immune to radio frequency, microwave, or power frequency electromagnetic fields, unaffected by external electromagnetic interference, ensuring signal stability and measurement accuracy in complex medical environments, and greatly expanding its clinical application scenarios.

[0061] Through the precise and coordinated operation of the aforementioned units, this device constructs a closed-loop intelligent blood gas monitoring system. Compared to existing technologies, this invention, through its all-fiber optic sensing architecture, completely eliminates the metal wires and electrode structures required by traditional electrochemical sensors, fundamentally eliminating electromagnetic interference problems and enabling the device to operate safely and continuously in strong electromagnetic environments such as magnetic resonance imaging. The multi-parameter fiber optic sensing probe, based on optical physics mechanisms rather than biochemical reactions, avoids signal drift caused by enzyme inactivation and protein contamination, significantly improving the long-term stability and lifespan of the sensor, enabling continuous monitoring for over 72 hours without external calibration. Through a distributed microcavity probe design and wavelength-time dual-resolution technology, simultaneous in-situ detection of multiple parameters—oxygen partial pressure, carbon dioxide partial pressure, pH value, temperature, and blood flow velocity—is achieved, breaking through the limitations of traditional catheter integration capabilities. The synergistic effect of the reference optical path compensation module and the cross-sensitivity correction unit effectively suppresses light source fluctuations, fiber loss, and environmental cross-interference, ensuring measurement accuracy. The non-invasive adaptive calibration mechanism further reduces the reliance on manual intervention, truly realizing minimally invasive, continuous, real-time, and highly reliable blood gas monitoring. It provides a brand-new technical means for intensive care, surgical anesthesia, and emergency treatment, greatly improving the quality and safety of patient monitoring.

[0062] Example 2

[0063] This embodiment, based on the aforementioned Embodiment 1, elaborates in more detail the preparation process and performance optimization of specific sensitive materials in the multi-parameter fiber optic sensing probe, with particular attention to their stability and biocompatibility under long-term in vivo retention conditions. This is crucial for achieving continuous monitoring for more than 72 hours. This embodiment will focus on the precision preparation of sol-gel films, the co-immobilization technology of polymer films, and the encapsulation process of fiber Bragg gratings.

[0064] For ruthenium complex-doped sol-gel membranes used in oxygen partial pressure probes, precise fabrication processes are crucial for ensuring sensor stability and lifespan. Sol-gel membrane preparation typically begins with the hydrolysis and condensation reaction of a silane precursor (e.g., tetraethoxysilane). To obtain a membrane with uniform pore size, good light transmittance, and optimal oxygen permeability, the pH, temperature, solvent ratio, and catalyst type and concentration are strictly controlled during the reaction process. Ruthenium complexes (such as tris(2,2'-bipyridine)ruthenium(II) chloride hydrate) are precisely metered and uniformly doped during the sol stage. In the membrane coating stage, a micro-injection pump is used for dip-coating or spray coating, precisely controlling the thickness of each coating, typically between 1 and 5 micrometers, to balance rapid oxygen diffusion with a sufficient number of luminescent centers. After coating, the membrane is slowly dried and cured under controlled humidity and temperature conditions, forming a porous silica matrix in which the ruthenium complex is physically embedded. To further enhance biocompatibility and anti-shedding performance, an ultra-thin, bio-inert polymer (such as polyvinyl alcohol or poly(hydroxyethyl methacrylate)) protective coating can be applied to the membrane surface. This protective layer prevents the leakage of ruthenium complexes, inhibits the adsorption of blood proteins and membrane biofouling, while not affecting the passage of oxygen molecules. During the production process, each batch of sol-gel membranes undergoes rigorous quality control testing for fluorescence lifetime characteristics, oxygen sensitivity, linear range, and response time to ensure batch-to-batch consistency.

[0065] For polymer membranes or dual-wavelength ratiometric fluorescent dye membranes co-immobilized with carbonic anhydrase used in carbon dioxide partial pressure probes and pH probes, the selection of the polymer matrix and the immobilization technique are crucial. Hydrogel materials, such as polyacrylamide, poly(hydroxyethyl methacrylate), or polyvinyl alcohol, are typically chosen as the polymer matrix due to their good biocompatibility, hydrophilicity, and tunable pore size.

[0066] Co-immobilization of carbonic anhydrase employs cross-linking technology, linking enzyme molecules to a polymer network via covalent bonds, or encapsulating them within polymer microspheres using microencapsulation. The choice of cross-linking agents, such as glutaraldehyde or carbodiimide, ensures maximum retention of enzyme activity during immobilization. pH-sensitive dyes (such as HPTS and SNARF) are also immobilized in the polymer matrix via covalent bonds or physical embedding. After membrane formation, its surface morphology requires meticulous control to maximize contact area with blood while minimizing the risk of thrombosis. For both probes, the membranes undergo rigorous testing for pH sensitivity, carbon dioxide sensitivity, selectivity, and long-term drift. By adjusting the polymer's cross-linking density and hydrophilicity, the membrane's permeability and ion exchange performance can be optimized, thereby precisely controlling the probe's response speed and linear range. To improve long-term stability, the polymer membrane undergoes UV or electron beam irradiation after curing to enhance its mechanical strength and resistance to degradation, and a parylene coating is applied to the surface to further improve biocompatibility and stability, effectively resisting bodily fluid erosion and biocontamination.

[0067] For the fiber Bragg grating used in the temperature probe, its long-term stability in the intravascular environment depends on precise encapsulation. The fiber Bragg grating itself is made of quartz glass, but it can be corroded by moisture and biomolecules in bodily fluids. Therefore, the grating portion requires special encapsulation before integration into the indwelling needle assembly. A common method is to use a metal coating, such as nickel or gold. A uniform, dense metal protective layer is formed in the grating area using electroplating or magnetron sputtering techniques. The metal coating not only provides excellent mechanical protection and moisture resistance but also improves the thermal conductivity of the fiber Bragg grating, resulting in a faster temperature response. However, since this device requires a completely metal-free design, a non-metallic encapsulation solution must be employed.

[0068] One metal-free encapsulation solution involves encapsulating the grating with high-strength, bio-inert ceramic materials or specialty polymers. For example, a grating is fused into a miniature ceramic sleeve and sealed with medical-grade epoxy resin. The ceramic sleeve, made of materials such as alumina or zirconium oxide, possesses excellent mechanical strength, corrosion resistance, and biocompatibility. The epoxy resin chosen must exhibit low shrinkage, high bond strength, and biocompatibility. During encapsulation, laser welding or precision adhesive bonding techniques are used to ensure a tight seal between the encapsulation material and the optical fiber, preventing the infiltration of bodily fluids. The encapsulated grating probe then undergoes temperature cycling and accelerated aging tests to evaluate its stability of reflected wavelength under physiological temperature fluctuations and long-term immersion conditions. Furthermore, the grating inscription process is optimized, for example, by using Type I or Type II fiber Bragg gratings to improve its radiation resistance and long-term temperature cycling stability, ensuring that temperature measurement accuracy remains unaffected during long-term continuous monitoring.

[0069] Through the precise fabrication and optimization of the aforementioned sensitive materials and probe structures, this embodiment not only ensures the performance stability and biosafety of each sensor probe in vivo, but also effectively extends the service life of the probe through sophisticated materials engineering and packaging technology. This enables it to reliably achieve continuous, minimally invasive blood gas monitoring for more than 72 hours, significantly reducing the replacement frequency due to sensor failure and secondary trauma to patients. This has profound clinical value for the long-term monitoring of critically ill patients.

[0070] Example 3

[0071] This embodiment further elaborates on the in-depth engineering implementation of the adaptive baseline drift suppression algorithm and non-invasive calibration mode in the central processing and display terminal, with particular focus on the specific technical path for dynamic offset correction by fusing auxiliary physiological signals such as patient surface pulse oxygen saturation, respiratory rate, and body temperature. This mode is key to maintaining high accuracy and reducing manual intervention in long-term continuous monitoring of this system.

[0072] The adaptive baseline drift suppression algorithm is a multi-stage intelligent data analysis process. First, the algorithm runs continuously in the background, monitoring all real-time received blood gas parameters (partial pressure of oxygen, partial pressure of carbon dioxide, pH, temperature, and blood flow velocity). The data is processed through a sliding time window, for example, calculating the moving average of data from the past 10 minutes every minute. Simultaneously, the algorithm maintains a long-term baseline model, constructed using exponentially weighted moving averages or linear regression analysis of historical data from the past 24 hours or longer, designed to characterize the "normal" physiological range and slow trend of change for each parameter. When the deviation between the average of the current sliding window and the predicted value of the long-term baseline model continuously exceeds a preset statistical threshold (e.g., 3 standard deviations) for a certain duration (e.g., 30 consecutive minutes), the algorithm identifies potential baseline drift. This threshold and duration parameter are optimized based on extensive clinical data and statistical methods (such as the Hotelling T-squared test) to effectively distinguish between physiological fluctuations and sensor drift. Once baseline drift is identified, the device automatically triggers a non-invasive calibration mode. The triggering mechanism is set to a high priority to ensure timely response to potential measurement errors.

[0073] Once the non-invasive calibration mode is activated, the central processing and display terminal will open the communication interface with external auxiliary physiological signal acquisition devices. These devices include, but are not limited to: a finger clip pulse oximeter (providing real-time pulse oxygen saturation SpO2 and heart rate data via Bluetooth or wired connection), a respiratory sensor (providing respiratory rate and respiratory waveform via chest or nasal sensors), and a body surface temperature sensor (providing body surface temperature data). All auxiliary signal data are synchronously acquired at a high sampling rate (e.g., 100 Hz) and timestamped to ensure the accuracy of data fusion.

[0074] The core calibration logic involves establishing a multi-input, multi-output calibration model to dynamically calculate the offset of fiber optic sensing data. This model employs a deep learning-based neural network architecture, such as a long short-term memory network or a convolutional neural network, which has the advantage of capturing complex nonlinear relationships and time-series dependencies between multimodal physiological signals. The model's input features include:

[0075] Raw output values ​​of the fiber optic sensor: partial pressure of oxygen, partial pressure of carbon dioxide, pH value, temperature, and blood flow velocity.

[0076] Auxiliary physiological signals: pulse oxygen saturation, respiratory rate, body surface temperature, heart rate, and may even include blood pressure (obtained via a non-invasive cuff blood pressure monitor).

[0077] Time-related characteristics: time since the last calibration, system uptime, ambient temperature and humidity, etc.

[0078] The model's output is the correction offset for each blood gas parameter. This neural network model was pre-trained on a large-scale clinical dataset before system deployment. The training data included paired data collected simultaneously from fiber optic sensors, a standard blood gas analyzer (as the gold standard), and auxiliary physiological signal devices. The training objective was to minimize the error between the corrected output of the fiber optic sensor and the gold standard. During training, the model learned how to predict and correct systematic drift of the fiber optic sensor using auxiliary physiological signals under different patient physiological states and sensor aging conditions. For example, when pulse oximetry indicates a patient is hypoxic, but the fiber optic oxygen partial pressure reading is abnormally high, the model calculates a negative correction offset based on the learned weights and offset patterns.

[0079] The specific dynamic offset correction process is as follows:

[0080] In non-invasive calibration mode, whenever new fiber optic sensor data and auxiliary physiological signal data arrive, they are input into a pre-trained neural network model in real time. The model immediately outputs a precise correction offset for the current fiber optic sensor data. For example, if the model calculates an offset of +2 mmHg for the oxygen partial pressure, the original reading of the current fiber optic oxygen partial pressure will be subtracted by 2 mmHg to obtain the correction value. This process is performed continuously at a high frequency (e.g., 10 times per second) to achieve dynamic offset correction of blood gas parameters. The corrected blood gas parameter data is then transmitted to the user interface of the central processing and display terminal for display and recorded in the historical database.

[0081] The implementation of this non-invasive calibration mode significantly improves the accuracy and reliability of the device in long-term continuous monitoring. It enables the device to intelligently adjust based on individual patient differences and minor sensor drift over time, without the need for repeated blood sampling or invasive calibration. This greatly improves patient comfort, reduces the risk of infection, and alleviates the workload of healthcare workers. This adaptive calibration strategy based on multimodal data fusion is the core supporting technology for achieving high-precision, long-term, minimally invasive continuous blood gas monitoring.

[0082] Example 4

[0083] This embodiment aims to elaborate on the engineering details of the special optical fiber and its cladding structure in the optical fiber indwelling needle assembly, the biocompatible coating treatment, and to explain in detail the safe operation mechanism of the completely metal-free design of the entire device in a magnetic resonance imaging environment, as well as its immunity to electromagnetic interference. These are important advantages that distinguish this device from traditional electrical sensors.

[0084] The selection of special optical fibers is crucial for the long-term stability and performance of the indwelling needle assembly. This device uses photonic crystal fiber or fluoride-doped silica fiber, which is resistant to bending loss.

[0085] Photonic crystal fibers transmit light by introducing periodically arranged air holes around the fiber core. The transmission mechanism can be either a modified total internal reflection principle or the photonic bandgap effect. This structure endows photonic crystal fibers with excellent resistance to bending loss; even at small bending radii (e.g., when indwelling needle assemblies bend within blood vessels), the attenuation of the optical signal is minimal, which is crucial for the application of optical fibers in flexible catheters. Furthermore, photonic crystal fibers can be designed to have zero dispersion or specific dispersion characteristics, which helps maintain the integrity of pulse signals and ensures accurate computation by the optical signal modulation and demodulation unit.

[0086] Fluoride-doped silica fiber is a special type of multimode or single-mode fiber. By doping fluorine into silica glass, the refractive index of the cladding is reduced, thereby achieving stronger optical field confinement. This type of fiber also exhibits excellent bending loss resistance and is often referred to as bend-insensitive fiber, designed to maintain low loss even when tightly wound or bent. Both photonic crystal fibers and fluoride-doped silica fibers share the advantage of having their core and cladding composed of high-purity silica glass, possessing excellent bioinertness and chemical stability, and will not react with blood components.

[0087] After manufacturing, the cladding structure of specialty optical fibers undergoes rigorous biocompatibility coating treatment. The selection of coating materials is extremely critical and must comply with international standards for medical implant materials (such as the ISO 10993 series). Commonly used biocompatibility coatings include:

[0088] Medical-grade polyimide coating: Polyimide is a high-strength, heat-resistant, and chemically inert polymer. Its coating provides excellent mechanical protection and a chemical barrier, preventing direct contact between the fiber optic surface and blood. Coating methods typically involve dip coating or mold coating followed by high-temperature curing.

[0089] Fluoropolymer coatings, such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), possess extremely low surface energy and excellent lubricity, effectively reducing blood protein adsorption and thrombus formation, and improving the sliding properties of optical fibers within blood vessels and their long-term anticoagulant performance. Coating is typically achieved using a dispersion dip-coating and sintering process.

[0090] Hydrophilic coatings, such as polyvinyl alcohol or poly(hydroxyethyl methacrylate) hydrogel coatings, can absorb moisture in the blood environment to form a water film, greatly reducing the surface friction coefficient and decreasing the adhesion of blood cells and proteins, further improving antithrombotic properties and biocompatibility. Hydrophilic coatings are typically applied as a secondary coating on top of the aforementioned basic protective layer.

[0091] Throughout the coating process, coating thickness and uniformity are strictly controlled to ensure that the coating provides sufficient protection without significantly increasing the outer diameter of the optical fiber, thus affecting its implantation within the indwelling needle catheter. Each batch of coated optical fibers undergoes comprehensive biocompatibility testing, including assessments of cytotoxicity, sensitization, irritation, and hemolysis, to ensure its safety in long-term in vivo placement.

[0092] The entire device features a completely metal-free design. This means that everything from the fiber optic indwelling needle assembly and multi-parameter fiber optic sensing probe to the probe connection of the optical signal modulation and demodulation unit, and even all components that come into direct contact with the patient, is made of non-metallic materials, such as polymers, quartz glass, and ceramics. All signal acquisition, transmission, and processing are accomplished through optical signals rather than electrical signals.

[0093] This completely metal-free design provides absolute safety for operation in magnetic resonance imaging (MRI) environments. Traditional electrical sensors, due to the electromagnetic induction generated by their metal electrodes and wires under strong magnetic fields and radio frequency pulses, can heat up and potentially burn patient tissue. Simultaneously, metal components can interfere with magnetic field homogeneity, producing artifacts in MRI images and affecting diagnostic quality. The metal-free nature of this device's fiber optic cable makes it completely transparent to MRI scans, eliminating any of the aforementioned risks. This allows patients to undergo MRI examinations while receiving continuous blood gas monitoring, which has extremely important clinical value for critically ill patients requiring long-term monitoring and repeated imaging evaluations.

[0094] Meanwhile, the pure optical signal transmission architecture gives the device natural immunity to radio frequency (RF), microwave, and power frequency electromagnetic fields (50 / 60 Hz). In modern hospital environments, there are numerous sources of electromagnetic radiation, such as high-frequency electrosurgical units, defibrillators, wireless communication devices, and various medical electronic devices. These electromagnetic fields can cause severe electromagnetic interference to traditional electrical sensor devices, leading to signal distortion, drift, or complete failure. Because this device does not rely on charge transmission, its optical signal transmission link is insensitive to electromagnetic fields, completely resisting these external interferences and ensuring stable and accurate blood gas monitoring data in any complex medical environment. This electromagnetic immunity significantly improves the system's robustness and clinical usability.

[0095] Through the description of this embodiment, this device not only provides high-precision physiological parameter monitoring, but also achieves in-depth adaptive optimization for clinical application environments in terms of materials, structure and signal transmission mechanism. In particular, it solves the monitoring gap in strong electromagnetic environments (such as MRI rooms) and the signal stability problem in complex electromagnetic interference environments (such as operating rooms and ICUs), bringing progress to modern medical monitoring technology.

Claims

1. An implantable real-time blood drug concentration monitoring device for surgical anesthesia, characterized in that, include: The system includes an optical fiber insertion needle assembly, a multi-parameter optical fiber sensing probe, an optical signal modulation and demodulation unit, a reference optical path compensation module, a temperature and pressure cross-sensitivity correction unit, and a central processing and display terminal. Among them, the fiber optic indwelling needle assembly is a hollow catheter structure made of medical-grade polymer material, which is embedded with one or more special optical fibers. The special optical fibers integrate multiple distributed fiber optic sensing probes in the catheter tip area. Multi-parameter fiber optic sensing probes are based on the physical response mechanisms of fluorescence lifetime, absorption spectrum or fiber Bragg grating to in situ sense the partial pressure of oxygen, partial pressure of carbon dioxide, pH value, temperature and flow rate in blood. The optical signal modulation and demodulation unit transmits excitation light pulses with specific wavelengths and pulse widths into special optical fibers and receives response light signals reflected or emitted by each sensing probe. The optical signal components corresponding to each parameter are separated by time-resolved or wavelength-resolved techniques. The reference optical path compensation module is located in the proximal non-implanted area of ​​the fiber optic indwelling needle assembly to provide a reference optical signal that is not affected by the blood environment, so as to eliminate systematic errors caused by light source fluctuations, fiber bending loss and connector aging. The temperature and pressure cross-sensitivity correction unit performs multi-dimensional decoupling operations on the original optical signal based on a pre-calibrated cross-sensitivity matrix, and outputs independent and accurate blood gas parameter values. The central processing and display terminal receives the calibrated blood gas parameter data, performs real-time trend analysis, abnormal warnings and visualization, and supports data docking with the hospital information system.

2. The implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The multi-parameter fiber optic sensing probes employ a modular microstructure design, with each probe spaced at intervals of no less than 5 mm along the fiber optic axis. Each probe contains a microcavity structure, the inner wall of which is coated with a fluorescent or absorption-sensitive material that selectively responds to specific blood gas components. The oxygen partial pressure probe uses a ruthenium complex-doped sol-gel membrane, whose fluorescence lifetime decays exponentially with increasing oxygen partial pressure. The carbon dioxide partial pressure probe uses a polymer membrane co-immobilized with a pH-sensitive dye and carbonic anhydrase, indirectly reflecting the carbon dioxide partial pressure by detecting changes in pH within the membrane. The pH probe uses a dual-wavelength ratiometric fluorescent dye membrane, where the intensity ratio of the two emission peaks is monotonically related to the hydrogen ion concentration. The temperature probe uses a fiber Bragg grating, whose reflected wavelength drifts linearly with temperature. The flow velocity probe employs a thermo-optical effect microstructure, estimating blood flow velocity by measuring the recovery time of local thermal disturbances.

3. The implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The optical signal modulation and demodulation unit includes a pulsed laser source, a wavelength division multiplexer, a photodetector array, and a high-speed digital signal processor; the pulsed laser source outputs excitation light with wavelengths of 405 nm, 470 nm, and 532 nm; the wavelength division multiplexer couples the multi-wavelength excitation light to the same special optical fiber and separates the returned response light according to wavelength to the corresponding photodetector. The high-speed digital signal processor performs time-gated acquisition, records fluorescence decay curves only within a preset time window, and calculates fluorescence lifetime using a least-squares fitting algorithm.

4. The implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The reference optical path compensation module includes a reference optical fiber manufactured in the same batch as the implanted optical fiber, with a fixed reflector at its end to form a stable Fabry-Perot interference structure; the reference optical path and the main sensing optical path share the same light source and detection channel, and the reference signal and sensing signal are acquired alternately through time-division multiplexing.

5. An implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The temperature and pressure cross-sensitivity correction unit incorporates a multi-dimensional correction model, which is built based on laboratory calibration data and covers the cross-response coefficients of oxygen partial pressure, carbon dioxide partial pressure, and pH value to temperature and hydrostatic pressure. The correction process uses matrix inverse operation to map the original multi-wavelength or multi-lifetime measurements to an independent physiological parameter space without cross-interference.

6. An implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The central processing and display terminal is equipped with an adaptive baseline drift suppression algorithm. The adaptive baseline drift suppression algorithm continuously monitors the historical trend of each parameter. When a slow drift is detected to exceed a preset threshold, the non-invasive calibration mode is automatically triggered. The non-invasive calibration mode dynamically corrects the offset of the fiber optic sensing data by integrating auxiliary physiological signals such as the patient's surface pulse oxygen saturation, respiratory rate, and body temperature.

7. An implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The outer diameter of the fiber optic indwelling needle assembly is no greater than 1.2 mm, and the length is 25 to 50 mm; the special optical fiber is a photonic crystal fiber or a fluoride-doped quartz fiber with a cladding structure treated with a biocompatible coating.

8. An implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 7, characterized in that, The biocompatible coating includes at least one of a polyimide coating, a fluoropolymer coating, or a hydrophilic coating, used to improve the anticoagulant ability and long-term placement safety of the optical fiber.

9. An implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 2, characterized in that, The sol-gel membrane has a thickness of 1 to 5 micrometers and a bio-inert polymer protective layer on its surface; the polymer membrane is used to immobilize carbonic anhydrase and pH-sensitive dye through cross-linking or microencapsulation technology; the fiber Bragg grating is encapsulated in a micro ceramic sleeve and sealed with medical-grade epoxy resin.

10. An implantable real-time blood drug concentration monitoring device for surgical anesthesia according to claim 1, characterized in that, The entire device is completely free of metal in its physical structure, and all signal transmission is completed through optical signals, thus enabling it to operate safely in the magnetic resonance imaging environment and is not affected by radio frequency, microwave or power frequency electromagnetic fields.

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