A hemostatic device for use in the field

Abstract

The application discloses a tourniquet device used on the battlefield, which comprises a pressurizing unit, a sensing unit, a control unit, a communication unit and an energy unit; the sensing unit at least comprises an intracavity air pressure detecting unit, a PPG sensor and a liquid leakage detecting unit; the control unit is configured to switch between a clinical mode and a battlefield first-aid mode, control the pressurizing unit to inflate the tourniquet, and evaluate the hemostasis state in combination with the pulsation signal collected by the PPG sensor; in the clinical mode, the minimum effective pressure for maintaining hemostasis is determined through micro-decreasing pressure relief, predictive pressure compensation is carried out in combination with the signal change rate of the liquid leakage detecting unit, and the total pressurizing duration is accumulated and controlled. The device can realize closed-loop adaptive control of the hemostasis process, improve the rapid hemostasis capacity in the battlefield environment, and reduce the risk of excessive compression and rebleeding.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically a hemostatic device used on the battlefield. Background Technology

[0002] Hemostasis is one of the most critical life support measures in battlefield trauma treatment, disaster emergency rescue, and clinical surgical management. In battlefield and major disaster scenarios, injuries to major arteries in the limbs, amputations, or limb amputations caused by bullets, explosions, and sharp objects are among the leading causes of rapid death among wounded soldiers. Such injuries often involve large amounts of bleeding and rapid progression, and wounded soldiers often cannot wait for professional medical assistance, requiring them to complete self-rescue or mutual rescue within minutes. At the same time, the operator may be in an adverse state such as a single-handed injury, physical exhaustion, a complex environment, or psychological stress. Therefore, extremely high requirements are placed on the speed, automation, closed-loop control capabilities, and environmental adaptability of hemostatic devices.

[0003] Existing pneumatic automatic hemostasis devices mostly rely on pre-set fixed air pressure thresholds for inflation and depressurization, representing a typical open-loop control method. This means the air circuit closes when threshold A is reached and pressurization stops when threshold B is reached, lacking real-time physiological feedback on tissue perfusion status, bleeding trends, or individual differences. Therefore, they have significant limitations in battlefield emergency scenarios. First, fixed thresholds are difficult to adapt to differences in blood pressure levels, vascular conditions, wound types, and injury sites among casualties, easily leading to insufficient hemostasis or excessive pressure. Second, existing devices typically maintain constant pressure after reaching the preset pressure, lacking dynamic assessment of hemostasis success and whether the current pressure is the minimum effective pressure. Prolonged high-pressure pressurization may increase the risk of limb ischemia. Third, existing effusion detection usually relies on simple threshold-triggered alarms or compensations, a reactive approach that fails to promptly identify and predictively intervene in bleeding progression. Finally, existing devices generally lack rapid hemostasis modes for high-intensity trauma such as major artery injuries and amputations. Their operation is cumbersome and lacks automation, failing to meet the practical needs of self-rescue and mutual aid in battlefield environments.

[0004] Furthermore, in clinical settings such as surgery, interventional procedures, and continuous pressure hemostasis after hemodialysis, appropriate control of external pressure is also necessary based on individual differences. For example, in hemostasis at the puncture site of an arteriovenous fistula after hemodialysis treatment, the blood pressure within the fistula is usually high, leading to persistent leakage at the puncture site after needle removal. Therefore, appropriate and continuous external pressure is required. Insufficient pressure will not effectively stop the bleeding, while excessive pressure may cause fistula stenosis, thrombosis, or even hypoxia in the extremities. Therefore, whether in battlefield emergency care or clinical pressure hemostasis scenarios, there is an urgent need for a hemostatic device that can adaptively adjust pressure based on physiological signal feedback, balancing rapid hemostasis with tissue protection. Summary of the Invention

[0005] In view of the common defects of the open-loop control strategy of existing hemostasis devices in clinical and battlefield scenarios described in the background art, the present invention proposes a hemostasis device for battlefield use.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A hemostatic device for use on the battlefield, comprising: The pressurization unit is used to inflate or deflate the tourniquet. The sensing unit includes at least an intracavitary pressure detection unit, a photoplethysmography (PPG) sensor, and a leakage detection unit; The control unit, electrically connected to the pressurization unit and the sensing unit, is configured to operate according to the following steps: Step S0: Operating Mode Selection. The control unit selects between "Clinical Mode" and "Battlefield First Aid Mode" based on user input or automatic injury assessment. The Battlefield First Aid Mode is specifically designed for high-intensity traumas such as major artery injuries, amputations, or limb amputations. Once triggered, it directly enters the rapid hemostasis and inflation process, omitting the gradual search phase in the conventional mode, to establish effective compression in the shortest possible time.

[0007] Step S1: Hemostasis Status Assessment. The control unit controls the pressurization unit to inflate the tourniquet to the initial pressure P0, and simultaneously activates the PPG sensor to continuously collect PPG signals from the puncture site or wound coverage area; the control unit extracts the pulsation component of the PPG signal and calculates the pulsation amplitude A(t); when A(t) is consistently below the hemostasis judgment threshold Ah and the duration exceeds the preset window Tw, it is determined that the current pressure has effectively suppressed local blood perfusion, the hemostasis assessment is passed, and proceeds to Step S2; otherwise, the pressure is increased by a step size. Increment the pressure and repeat the assessment until the assessment is passed or the pressure reaches the safe upper limit Pmax. In battlefield first aid mode, if a missing or extremely weak PPG signal is detected (indicating rapid blood loss from a major artery), directly increase the pressure to Pmax and lock it, then proceed to step S3.

[0008] Step S2: Minimum Effective Pressure Search. After the hemostasis assessment is passed, the control unit gradually reduces the pressure of the tourniquet by a preset step size ΔP2. After each pressure reduction, a stabilization time Ts is waited, and the PPG signal is collected again to calculate the pulsation amplitude A(t). If A(t) is still lower than the hemostasis judgment threshold Ah, the pressure continues to decrease. Once A(t) exceeds the threshold Ah or the exudation detection unit signal exceeds the exudation warning lower limit, the pressure reduction is immediately stopped, and the current pressure is increased. The maintenance pressure Pm is then set; Pm is the minimum effective pressure required to maintain hemostasis under the current physiological state. In battlefield first aid mode, this step is skipped, and Pmax is used directly as the maintenance pressure Pm.

[0009] Step S3: Predictive Leakage Compensation. During the pressure maintenance phase, the control unit operates at a fixed sampling period. The signal value B(t) of the seepage detection unit is continuously collected, and the rate of change of the seepage signal is calculated. ;when Exceeding the preset exudation acceleration threshold Even if the current leakage volume has not yet reached the alarm threshold, the control unit will trigger pressure compensation in advance: in steps. Increase tourniquet pressure and simultaneously issue a warning sound via audio module; when Continuously exceeding a higher threshold When the control unit determines that there is a serious risk of leakage, it immediately and rapidly increases the pressure to the upper pressure limit Pmax, and sends an alarm message to the cloud server or the accompanying emergency terminal through the wireless data transmission unit.

[0010] The pressure compensation amount does not use a fixed step size. Instead, it is based on the heart rate HR(t), blood oxygen saturation SpO2(t), and blood perfusion index PI(t) collected in real time by the PPG sensor to construct the physiological state comprehensive index PSI(t). The pressure bias term δP(t) is then dynamically calculated using PSI(t). The specific steps are as follows: Using the HR0 and SpO collected when entering step S3 20 Using PI0 as the baseline value, the normalized changes of the three physiological signals were calculated respectively: ; ; ; Construct a comprehensive physiological state index using a weighted summation method: ; in PSI(t) is limited to [0,1] after being clipped. The pressure deviation term is dynamically calculated using PSI(t): ; Where K is the gain coefficient and Pmax is the upper limit of the safe pressure, and Pm is the minimum effective maintaining pressure determined in step S2. Calculate adaptive target maintenance pressure: ; Satisfying constraints The control unit is based on Dynamic pressure adjustment is applied to the tourniquet.

[0011] The weighting coefficients w1, w2, and w3 are preset according to the application scenario: In battlefield emergency mode, w2 has the largest weight corresponding to blood oxygen saturation SpO2(t) to prioritize the response to the rapid drop in blood oxygen caused by hemorrhagic shock; in clinical mode, w3 has the smallest weight corresponding to the baseline values ​​HR0 and SpO2(t) of blood perfusion index PI(t). 20 After each pressure compensation is performed in step S3, PI0 is re-acquired and updated. The new physiological state after pressure compensation is used as the comparison benchmark for the next calculation cycle to prevent baseline drift from causing distortion in PSI(t) calculation.

[0012] Step S4: Pressurization Time Control and Deactivation. The control unit has a built-in pressurization timer that tracks the total pressurization time. Perform real-time accumulation; when Reaching the preset limit It will automatically enter a stepped decompression process to prevent limb ischemia and injury caused by prolonged high pressure; in battlefield emergency mode, medical personnel will dynamically extend the upper limit of the pressure application time according to the severity of the injury. It also reports the duration of pressurization in real time via wireless data transmission, allowing medical personnel at the rear to assess the injury.

[0013] The above method also includes: the control unit integrates the heart rate value, blood oxygen value and blood perfusion index measured by the PPG sensor to monitor the patient's overall physiological status in real time, and uploads the monitoring data to the cloud server or the accompanying emergency terminal through the wireless data transmission unit; when the cloud server does not receive data updates within a preset time window, it determines that the device may have been removed in advance and issues a prompt.

[0014] In step S1 above, the initial pressure P0 is determined according to the operator's preset value in clinical mode; in battlefield emergency mode, the initial pressure P0 can be automatically set by the control unit according to the signal strength of the effusion detection unit and the degree of PPG signal loss, so as to achieve rapid and effective compression.

[0015] The device also includes a communication unit, which is electrically connected to the control unit and is used to send physiological monitoring data and alarm information to an external terminal or cloud server.

[0016] The device also includes an audio output module for issuing alerts of different intensities and rhythms during leakage warnings and serious alarms.

[0017] The device also includes a display unit electrically connected to the control unit, used to display in real time the heart rate value, blood oxygen value, blood perfusion index and current tourniquet pressure value measured by the PPG sensor.

[0018] This device also includes an energy unit that provides electrical power to the aforementioned units.

[0019] Compared with existing technologies, the present invention provides a battlefield hemostasis device that, through the coordinated operation of a pressurization unit, a sensing unit, and a control unit, and combined with physiological signals and exudate signals for closed-loop control, can adaptively adjust the pressurization process according to the actual hemostasis state. This effectively solves the problems of insufficient battlefield adaptability, low hemostasis control precision, and lack of dynamic feedback in existing hemostasis devices. Specifically, the present invention has at least the following beneficial effects: (1) Achieve closed-loop adaptive hemostasis control. Using the PPG signal pulsation amplitude as the objective evaluation criterion for hemostasis effect, it completely replaces the existing fixed threshold open-loop control mode, and realizes adaptive closed-loop pressure regulation with actual physiological hemostasis effect as the feedback core, fundamentally eliminating the problem of insufficient hemostasis or excessive pressure caused by individual differences.

[0020] (2) Dynamically optimize maintenance pressure to reduce the risk of tissue ischemia and injury. Through a micro-decreasing pressure release iterative algorithm, the maintenance pressure is automatically optimized to the individualized minimum necessary level while ensuring hemostasis. This effectively shortens the duration of high-pressure pressurization and reduces the risk of fistula function damage and limb ischemia and injury in dialysis patients, demonstrating significant clinical safety value.

[0021] (3) Predictive compensation for exudation trend significantly improves the timeliness of intervention. Based on the sliding linear regression algorithm of the exudation signal change rate, the timing of exudation intervention is advanced from "post-event response" to the "trend prediction" stage. Pressure compensation is completed before the exudation volume reaches the alarm threshold, which effectively prevents the exudation from worsening. It is especially important for the life protection of patients with massive battlefield hemorrhage.

[0022] (4) Dedicated battlefield first aid mode, empowering self-rescue and mutual rescue capabilities. The battlefield first aid mode supports quick activation with one hand. The device automatically completes injury assessment, inflation and pressurization and hemostasis effect evaluation without manual parameter setting. It can establish effective compression hemostasis for major artery injuries, amputations or limb stumps within seconds, greatly reducing the mortality rate of battlefield bleeding and providing combat personnel with reliable self-rescue and mutual rescue techniques.

[0023] (5) Remote data reporting to support continuous monitoring and command decision-making. The wireless data transmission unit uploads the pressurization duration, patient heart rate, blood oxygen, blood perfusion index and exudation status to the cloud server or the accompanying emergency terminal in real time, supporting medical staff or command personnel to carry out remote continuous monitoring of dialysis patients and battlefield casualties, and providing data support for determining the priority of treatment.

[0024] (6) Independent control of arterial and venous dual-pathway to adapt to the needs of multiple trauma sites. The arterial and venous dual-tetherway airway control mechanism enables this device to treat two puncture sites or trauma sites, arteries and veins at the same time, and apply different levels of pressure according to their respective physiological needs, thereby improving the device's adaptability to complex trauma scenarios. Attached Figure Description

[0025] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings: 10—Adaptive hemostasis pressure control device; 11—Pneumatic pressurizing pump; 12—Intracavitary pressure detection unit; 13—Gas path diversion chamber; 14—First inflation and pressurization belt; 15—Gas release valve; 16—Loop switching valve; 17—Second inflation and pressurization belt; 18—Central control module; 19—First leakage detection unit; 21—First PPG sensor; 22—Second leakage detection unit; 23—Second PPG sensor; 24—Display unit; 25—Energy storage module; 26—Wireless data transmission unit; 81—First gas conduit; 82—Second gas conduit; 83—Third gas conduit; 84—Fourth gas conduit; 85—Fifth gas conduit; 86—Sixth gas conduit.

[0026] Figure 1 A schematic diagram of the control process of a hemostatic device used on the battlefield; Figure 2 A schematic diagram of the overall structure of a battlefield hemostatic device applied to a limb; Figure 3 This is a side view diagram of a battlefield hemostatic device applied to a limb. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] All standard parts used in this application can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt mature and conventional methods in the prior art, and the components used in the circuit connection are all conventional models in the prior art.

[0030] Meanwhile, in order to clearly express the connection relationship and working principle between the components and highlight the key points, the accompanying drawings in the instruction manual are organized and drawn in the form of simplified diagrams. One simplified diagram can correspond to multiple materials and actual external structural shapes.

[0031] Example 1 See Figures 1-3 In this embodiment, the central control module 18 is electrically connected to the pneumatic pressurizing pump 11, the gas release valve 15, the cavity pressure detection unit 12, the loop switching valve 16, the first leakage detection unit 19, the first PPG sensor 21, the second leakage detection unit 22, and the second PPG sensor 23. The gas path diversion chamber 13 is connected to the pneumatic pressurizing pump 11 via the first gas conduit 81; the first inflation and pressurization belt 14 is connected to the gas path diversion chamber 13 via the second gas conduit 82; the gas release valve 15 is connected to the gas path diversion chamber 13 via the third gas conduit 83; the loop switching valve 16 is connected to the cavity pressure detection unit 12 via the fourth gas conduit 84, and the loop switching valve 16 is connected to the gas path diversion chamber 13 via the fifth gas conduit 85; the second inflation and pressurization belt 17 is connected to the loop switching valve 16 via the sixth gas conduit 86, and the loop switching valve 16 is used to open or close the sixth gas conduit 86.

[0032] In battlefield first aid applications, the first inflatable compression band 14 and / or the second inflatable compression band 17 can be applied to different limb injury sites depending on the injury situation, to provide rapid compression and hemostasis for major artery injuries, amputations, or limb stumps. In clinical applications, the first inflatable compression band 14 is wrapped and bound around the arterial fistula puncture site, and the second inflatable compression band 17 is wrapped and bound around the venous fistula puncture site.

[0033] The first exudate detection unit 19 and the first PPG sensor 21 are disposed on the first inflatable pressure belt 14, corresponding to the arterial puncture site or arterial injury site; the second exudate detection unit 22 and the second PPG sensor 23 are disposed on the second inflatable pressure belt 17, corresponding to the venous puncture site or venous injury site.

[0034] The implementation process of battlefield first aid mode is as follows, taking battlefield gunshot wounds causing damage to the major artery in the forearm as an example to illustrate the specific implementation process of battlefield first aid mode.

[0035] The design goal of the battlefield first aid mode is to enable wounded soldiers to quickly put on and activate hemostatic devices with one hand or by their comrades when there is no assistance from professional medical personnel, to establish effective hemostatic pressure in the shortest possible time, and to automatically assess the hemostatic effect during the pressure application process, thereby reducing human intervention.

[0036] Step S0: The wounded soldier or comrade places the first 14 sets of inflatable pressure straps at an appropriate position proximal to the injured limb (in the case of amputation, place the straps above the stump), and presses the battlefield first aid mode activation button or triggers the preset quick activation gesture. The control unit confirms that the mode is battlefield first aid mode, initializes the sensors, and enters the rapid inflation process.

[0037] Step S1, Rapidly Establish Compression: The control unit commands the pressurization unit to inflate the tourniquet at the maximum rate, while continuously monitoring the intracavitary pressure detection unit value and the PPG sensor signal. If the PPG signal is extremely weak or absent during inflation (indicating significant blood loss and extremely low perfusion at the wound site), the control unit determines it to be a high-intensity trauma, directly and rapidly inflating the pressure to the safe upper limit Pmax and locking it to ensure complete compression hemostasis is achieved in the shortest possible time, then proceeding to step S3. If the PPG signal has an analyzable pulsatile component, the same hemostasis status assessment logic as in the clinical mode is executed (i.e., judging the hemostasis effect by comparing A(t) and Ah). After the assessment is passed, the current pressure is locked, and the process proceeds to step S3.

[0038] Step S2: In battlefield first aid mode, given the priority of hemostasis efficiency, the minimum effective pressure search phase is skipped, and the current pressure when the hemostasis status assessment is passed, Pmax or the current pressure when the hemostasis status assessment is passed, is directly locked as the maintenance pressure Pm.

[0039] Step S3: The logic is the same as in clinical mode. In battlefield emergency mode, once an accelerating exudation trend is detected, the control unit prioritizes rapid pressure compensation with the maximum step size and issues a high-intensity alarm sound through the audio unit to prompt colleagues to take action or transfer the patient.

[0040] Step S4, in battlefield first aid mode, pressurization time limit The duration is automatically extended based on the severity of the injury (e.g., in cases of amputation). The duration is 180 minutes. The duration of pressurization, the patient's physiological signs and the status of the device are reported in real time to the accompanying emergency terminal or the rear medical command system through the wireless data transmission unit, so as to assist the rear medical personnel in assessing the severity of the injury and the priority of treatment.

[0041] The battlefield first aid mode of the present invention fully considers the actual constraints of battlefield self-rescue and mutual rescue: (1) The operation process is extremely simple, and the fastest operation can be completed by one hand to put on and trigger the device without the need for complicated parameter settings; (2) The device automatically completes pressure judgment and locking, reducing human operation errors; (3) The lightweight energy storage module 25 (e.g., lithium battery) supports long-term continuous operation; (4) The wireless data transmission and reporting capability ensures that the information of the wounded can be grasped by the rear in real time, providing data support for battlefield casualty treatment.

[0042] Taking hemostasis at the puncture site after dialysis as an example, the specific implementation process of the control method of the present invention is explained.

[0043] Step S0: The operator selects "Clinical Mode" on the display screen 24, and the central control module 18 initializes each sensor and confirms that the device is in normal condition.

[0044] Step S1, Hemostasis Status Assessment: The central control module 18 commands the pneumatic pressurization pump 11 to inflate the first inflatable pressurization band 14 to an initial pressure P0 (e.g., 100 mmHg), and simultaneously activates the first PPG sensor 21 to collect PPG signals from the arterial puncture site area. The central control module 18 extracts the pulsation component from the PPG signal and extracts the pulsation amplitude A(t). If A(t) is lower than the hemostasis judgment threshold Ah within the time window Tw (e.g., 10 seconds), it is determined that the arterial puncture site has been effectively suppressed; otherwise, the central control module 18 commands the pneumatic pressurization pump 11 to pressurize the first inflatable pressurization band 14 in steps... (e.g., 10 mmHg) Increment the inflation pressure and reassess. When the intracavitary pressure detection unit 12 detects that the intracavitary pressure has reached the second predetermined value, the central control module 18 commands the pneumatic pressurizing pump 11 to stop inflation to prevent overpressure. On the venous tourniquet side, when the intracavitary pressure detection unit 12 detects that the pressure has reached the first predetermined value, the central control module 18 commands the loop switching valve 16 to close the sixth gas conduit 86. Thereafter, the gas delivered by the pneumatic pressurizing pump 11 is only introduced into the first inflation and pressurizing band 14 (arterial side) and no longer enters the second inflation and pressurizing band 17 (venous side), which helps to continuously increase the pressure on the arterial side—the arterial puncture site requires greater pressure than the venous puncture site to achieve hemostasis.

[0045] Step S2, after the arterial side hemostasis assessment is passed, the central control module 18 controls the gas release valve 15 in steps. (e.g., 5 mmHg) The first inflation and pressurization belt 14 is depressurized gradually, with a wait of Ts (e.g., 5 seconds) after each depressurization, and the PPG signal is collected again. If A(t) is still lower than Ah and the signal of the first seepage detection unit 19 does not exceed the seepage warning lower limit... If A(t) exceeds Ah or the effusion signal exceeds..., then continue to decrease; Immediately stop depressurization; the central control module 18 will increase the current pressure. (For example, 10 mmHg) is then used as the maintenance pressure Pm and locked. At this point, the device has automatically completed the search for the minimum effective blood pressure, ensuring hemostasis while minimizing the impact of high pressure on the limb.

[0046] In step S3, during the pressure maintenance phase, the central control module 18 continuously acquires the signal values ​​B1(t) and B2(t) of the first seepage detection unit 19 and the second seepage detection unit 22 at fixed intervals, and calculates the seepage signal change rate respectively. and .when Exceeding the exudation acceleration threshold At that time, the central control module 18 triggers pressure compensation in advance, in steps. Increase the pressure of the first inflation and pressurization belt 14, and simultaneously trigger an alarm sound from the device; when Persistently exceeding the severity threshold If a serious leakage risk is detected, the pressure is immediately increased to Pmax and a continuous alarm is issued. Simultaneously, the alarm information is sent to the cloud server via the wireless data transmission unit 26. The second leakage detection unit 22 uses the same logic for monitoring leakage on the venous side.

[0047] Step S4: The central control module 18 has a built-in timer to record the total pressurization duration. Real-time accumulation (typically about 2 hours in clinical settings). When Reaching the preset limit The device will automatically enter a stepped depressurization process to prevent limb ischemia-reperfusion injury caused by prolonged high pressure. In addition, if the wireless data transmission unit 26 fails to successfully upload physiological data to the cloud server within a preset time window, the central control module 18 determines that the device may have been removed prematurely and notifies the user through the display screen 24 and an audio prompt.

[0048] During the above process, the first PPG sensor 21 and the second PPG sensor 23 simultaneously collect the patient's heart rate, blood oxygen value and blood perfusion index. After being integrated and processed by the central control module 18, the data is displayed on the display screen 24 and uploaded to the cloud server via the wireless data transmission unit 26 for remote monitoring by medical staff.

[0049] Example 2 To fully disclose the technical solution of the present invention, the signal processing method, decision logic, parameter tuning principle and anomaly handling mechanism involved in steps S1 to S4 are described in detail below.

[0050] S1. PPG signal acquisition and pulsation amplitude extraction; (1.1) Acquisition of raw signals; PPG sensor 21 (first photovolume change mapping sensor 21) and PPG sensor 23 (second photovolume change mapping sensor 23) continuously acquire the raw sequence of light reflection intensity of the puncture site or wound coverage area at a sampling rate of not less than 100 Hz. During the acquisition process, the central control module 18 first applies a DC bias to the input signal to remove the high-pass cutoff frequency. To filter out the DC component caused by skin background reflection and circuit baseline drift, an AC coupling sequence is obtained. .

[0051] (1.2) Bandpass filtering and pulsation component extraction; 18 pairs of central control modules A bandpass filter was applied, with a passband range of 0.5 Hz to 4.0 Hz (corresponding to heart rates of 30 bpm to 240 bpm). An 8th-order Butterworth IIR filter was used to balance phase linearity and computational complexity. The filtered result was a sequence containing the cardiac cycle pulsation components. .

[0052] In embedded implementations with limited computing resources, the moving average difference method can also be used as an alternative to IIR filtering: ; in , The sliding window lengths corresponding to the cutoff frequencies of 0.5Hz and 4.0Hz, respectively (calculated based on the sampling rate).

[0053] (1.3) Pulsation amplitude Calculation; The central control module 18 has a length of Within a sliding time window (preset to 10 seconds), for Perform the following operations: Extract all local maxima (crest set) within the window ) and local minima (set of troughs) ); The average amplitude difference between adjacent peak-trough pairs is taken as the pulse amplitude of a single cardiac cycle. Take the median of all valid cardiac cycle amplitudes within the window as the current beat amplitude. To suppress extreme value interference caused by motion artifacts.

[0054] The formula is expressed as: ; (1.4) Signal Quality Assessment (SQI); To prevent incorrect hemostasis decisions when the signal is extremely weak or the noise is excessive, the central control module 18 calculates the signal quality index (SQI) synchronously during each calculation: ; in This represents the standard deviation of the original AC signal within the window. When the default value is 1.5, the central control module 18 determines that the current PPG signal quality is insufficient, suspends the hemostasis assessment, and displays "Insufficient signal quality, please check the sensor adhesion status" on the display screen 24, while extending the waiting time until the signal quality is restored. In battlefield first aid mode, when the SQI remains below a certain value... If the time exceeds 3 seconds, the central control module 18 directly determines that the perfusion is extremely low due to massive blood loss and triggers rapid inflation. Emergency procedures.

[0055] (1.5) Threshold for determining hemostasis The determination; Hemostasis threshold An adaptive baseline method is used to determine the baseline pulsation amplitude: During initial device startup (before inflation, when the tourniquet pressure is zero), the central control module 18 acquires a 5-second PPG signal and calculates the baseline pulsation amplitude. ; The hemostasis threshold is set to The proportionality coefficient The default value is 0.15 (i.e., 15% of the baseline amplitude). This proportionality coefficient The value can be adjusted by the operator within the range of 0.05 to 0.30 according to individual patient differences (such as thicker subcutaneous fat and lower baseline amplitude in obese patients); If an effective baseline cannot be obtained before initial inflation (e.g., directly strapping on in battlefield first aid mode), then Use fixed preset values.

[0056] S2. Minimum Effective Pressure Search Algorithm; (2.1) Gradual depressurization process; After passing the hemostasis assessment ( and After that, the central control module 18 enters the minimum effective pressure search phase. The gas release valve 15 performs fine venting using pulse width modulation (PWM) control, with each pressure release step being [length missing]. mmHg, after each step, close the gas release valve 15 and wait for stabilization time. Seconds (this time window covers at least 3 to 4 normal cardiac cycles to ensure that the PPG signal fully responds to pressure changes).

[0057] (2.2) Search termination conditions; Central control module 18 in each wait After completion, recalculate. And determine whether any of the following termination conditions are met: Condition C1 (Detection of blood flow reperfusion): This indicates that the tourniquet pressure has fallen below the minimum value required to maintain effective pressure, and local blood flow has begun to recover; Condition C2 (Leakage Warning Trigger): Current sampled value of leakage detection unit 19 or 22 Exceeding the lower limit of the leakage warning (This threshold corresponds to the typical output of the leakage detection unit under slightly damp conditions and is determined by factory calibration.) Condition C3 (Pressure Lower Limit Protection): The current tourniquet pressure has dropped to the preset minimum protection pressure. (The default value for clinical mode is 30 mmHg to prevent acute bleeding caused by complete loosening of the tourniquet).

[0058] When any condition is met, the central control module 18 immediately closes the gas release valve 15, stops the decrease, and adds the pressure recovery amount to the current reading of the cavity gas pressure detection unit 12. (The preset value is 10 mmHg, as a safety margin) and this value is then used as the maintaining pressure. Write to the register and lock. Subsequently, the pneumatic pressurization pump 11 detects a pressure lower than [a certain value] in the cavity when the air pressure detection unit 12 detects that the pressure is [a certain value]. Automatic micro-injection of air at (dead zone compensation amount, preset value is 2 mmHg) to maintain stable air pressure. .

[0059] (2.3) Guarantee of search convergence; To prevent the search process from oscillating around a certain pressure value due to signal jitter, the central control module 18 introduces the following safeguard mechanism: Only when The termination condition C1 is triggered only when both conditions are met within two consecutive evaluation windows, thus avoiding misjudgment of a single noise impulse. If pressure is released three times consecutively None exceeded and Not exceeding The central control module 18 will be expanded to 10 mmHg to speed up the search and prevent excessively long search times in patients with low perfusion or obesity. The total pressure relief during the search shall not exceed the pressure from the time of assessment to... If the range is exceeded, it will be forced to use... As .

[0060] S3. Leakage signal processing and predictive compensation algorithm; (3.1) Acquisition of signals from the seepage detection unit and baseline correction; Leakage detection unit 19 (first leakage detection unit 19) and leakage detection unit 22 (second leakage detection unit 22) operate at a fixed sampling period. Acquire impedance or optical transmission intensity signals per second and output the original sequence. The central control module 18 applies an exponentially weighted moving average (EWMA) filter to the original sequence to suppress random noise. ;wherein the smoothing coefficient (That is, the time constant is approximately 3 seconds). During the device initialization phase (dry state before pressurization), the central control module 18 records... The following is based on As an incremental indicator of exudate volume, it eliminates the influence of individual differences and initial sensor bias.

[0061] (3.2) Permeation change rate The estimate; The central control module 18 has a length of Within a sliding window of seconds (configurable), for The sequence was subjected to least squares linear regression, and the slope of the regression line was used as an estimate of the rate of change of the effusion signal. ; The purpose of using linear regression instead of adjacent difference is that linear regression utilizes all samples within the entire time window, has a natural smoothing effect on random noise, and can effectively suppress short-term fluctuations caused by changes in body position, small sensor displacements, etc., to obtain a more robust trend estimate.

[0062] At the same time, the central control module 18 calculates the coefficient of determination for the regression. ;when If this occurs, it indicates that the seepage signal within the current window is not monotonic (potentially spurious noise), and the central control module 18 will not use this time as the basis for its operation. Instead of triggering compensation, we continue to wait for the evaluation results of the next cycle.

[0063] (3.3) Multi-level threshold decision and compensation response; Central control module 18 based on Depending on the size, the following three-level response strategy will be implemented, as shown in Table 1: Table 1. Three-Level Response Strategy Table

[0064] After the early warning level compensation, if Recover within 30 seconds The following maintains pressure The new value after compensation should remain unchanged and not automatically decrease to prevent repeated leakage; if there are three consecutive warning-level compensations... If the situation does not improve, the alert level will be upgraded to an alarm level.

[0065] (3.4) Joint decision-making of dual-channel effusion signals; When the device simultaneously monitors both the arterial side (exudate detection unit 19, corresponding to the first inflatable pressure band 14) and the venous side (exudate detection unit 22, corresponding to the second inflatable pressure band 17), the central control module 18 independently executes the aforementioned three-level decision for both signals, and follows the principle of "global escalation upon any channel reaching the alarm level": that is, when the venous side exudate detection unit 22 reaches the alarm threshold, the arterial side tourniquet 14 is also triggered to increase pressure. This is to prevent delayed response when both puncture sites leak fluid simultaneously.

[0066] 4. Pressurization time control and stepped depressurization algorithm; (4.1) Logic of the pressure timer; The central control module 18 has a built-in software timer that tracks the total pressurization time from the moment of initial inflation. Monotonic accumulation is performed (only accumulation, no reset due to mid-term pressure release). Every 60 seconds, the central control module 18 updates the pressurization time display on the display screen 24, and transmits it via the wireless data transmission unit 26. The current air pressure, heart rate, blood oxygen level, and effusion status are uploaded to the cloud server for remote medical personnel to monitor.

[0067] (4.2) Stepped pressure relief process; when Reaching the preset upper limit (In clinical mode, the default time is 120 minutes). The central control module 18 will automatically initiate a stepped depressurization process, with the following steps: Phase 1: Maintain pressure by decreasing it every 5 minutes 10%, then evaluated in real time after decreasing. ;like (Blood flow resumes reperfusion), pause and gradually decrease, maintain the current pressure for 5 minutes before continuing; Phase Two: When the air pressure drops to... When the concentration is below 50%, the rate is reduced every 5 minutes, and the signal from the seepage detection unit is monitored simultaneously. Phase Three: When the air pressure drops to... When the blood pressure is below 30 mmHg, the leakage detection unit signal is continuously monitored for 60 seconds. If there is no abnormality, the pressure is completely released, a "removable" prompt sound is emitted, and "hemostasis completed, device removable" is displayed on the display screen 24.

[0068] If detected at any stage of the stepped pressure relief If the warning threshold is exceeded, the central control module 18 immediately stops depressurization and recharges to the specified level. It then re-enters the effusion monitoring cycle, displaying "Hemostasis not complete, do not remove" and issuing a warning sound.

[0069] (4.3) Accidental removal detection; The central control module 18 has a built-in "accidental removal" detection logic: when the intracavitary pressure detection unit 12 detects a sudden drop in intracavitary pressure without a pressure relief command (pressure drops by more than 20 mmHg within 10 seconds) and there is no corresponding gas release valve 15 opening command, it determines that the tourniquet may have been accidentally or prematurely removed, and immediately sends a removal event alarm packet to the cloud server through the wireless data transmission unit 26, and displays a warning message on the display screen 24 to remind medical staff to check.

[0070] 5. Algorithm differentiation processing for battlefield first aid mode; (5.1) Rapid inflation rate control; After the battlefield first aid mode is activated, the central control module 18 outputs a PWM drive signal with the maximum duty cycle to the pneumatic pressurization pump 11 to inflate the tourniquet at the highest inflation rate. Simultaneously, the central control module 18 polls the intracavitary pressure detection unit 12 at a frequency of 10Hz to monitor the inflation process in real time. When the reading of the intracavitary pressure detection unit 12 exceeds... When the pressure reaches mmHg, the central control module 18 switches to a low-speed micro-injection mode, precisely approaching the target pressure. This is to prevent overpressure shocks from damaging the gas circuit components.

[0071] (5.2) Criteria for determining PPG deficiency; During battlefield first aid inflation, the central control module 18 simultaneously assesses the SQI of the PPG signal. If either of the following two conditions is met, the PPG signal is determined to be missing or extremely weak: Within 5 consecutive seconds (Signal quality index remains below the threshold). (The pulsation amplitude is less than 5% of the baseline, which is replaced by the factory calibration reference value at the time of initial power-on).

[0072] If any of the conditions are met, the central control module 18 determines it to be a high-intensity trauma (massive blood loss, extremely low perfusion) and directly locks the system. .

[0073] (5.3) Differences in seepage compensation under battlefield mode; In battlefield first aid mode, the step size for infiltration warning-level compensation is changed from... Adjusted to The waiting time after each compensation is reduced from 30 seconds to 10 seconds to prioritize hemostasis efficiency. The alarm-level response logic is the same as the clinical mode, but the alarm information is sent to the accompanying emergency terminal (instead of the cloud server) to adapt to situations where battlefield network conditions are limited.

[0074] (5.4) Automatic assessment of injury severity and Dynamic extension; In battlefield first aid mode, the central control module 18 comprehensively assesses the severity of injuries based on the following indicators and dynamically sets... : Injury Grade I (General limb injury, PPG available, no signs of significant blood loss): minute; Injury level II (moderate blood loss, weak but analyzable PPG, SQI between 0 and 1): minute; Injury grade III (high-intensity trauma, PPG loss, major artery injury or amputation): minute.

[0075] The results of the injury assessment and severity evaluation are reported in real time through the wireless data transmission unit 26, which is used by the rear medical command system to assist in determining the priority of evacuation and treatment.

[0076] 6. Physiological parameter monitoring and data upload protocol; (6.1) Calculation methods for heart rate and blood oxygen; The central control module 18 uses the signals synchronously collected by PPG sensors 21 and 23 to perform the following physiological parameter calculations: Heart rate (HR): after bandpass filtering Perform autocorrelation analysis to identify the location of the main peak, calculate the instantaneous heart rate using the reciprocal of the interval between adjacent peaks, and take the mean of all effective cardiac cycle intervals within a 30-second window and convert it to bpm; Blood oxygen saturation (SpO2): If the PPG sensor has the capability to acquire both red light (660nm) and infrared light (940nm) at dual wavelengths, the central control module 18 calculates the ratio (R value) of the AC component to the DC component of the two signals, and uses an empirical formula. (coefficient , Blood oxygen saturation is estimated (as determined by factory calibration). Perfusion index (PI): defined as ,in The PI value represents the average DC component of the PPG signal. The PI value reflects the intensity of local microcirculation perfusion and can help assess the peripheral circulation status of the limb during hemostasis. (6.2) Data upload structure; The central control module 18 uploads data to an external terminal or cloud server every 60 seconds via the wireless data transmission unit 26 (supporting BLE5.0 / Wi-Fi / LoRa, switching according to the scenario). The upload cycle is automatically compressed to 10 seconds to ensure real-time data during the seepage deterioration stage.

[0077] (6.3) Offline caching and retransmission after disconnection; When the wireless link is interrupted, the central control module 18 writes the data to be uploaded into the local Flash storage (circular buffer with a capacity of not less than 24 hours of full-frequency collected data). After the link is restored, the cached data is automatically uploaded to the cloud in batches, along with the original timestamp of each data packet, to ensure that the integrity of historical data is not lost due to communication interruption.

[0078] The above covers the complete algorithm for PPG signal filtering and amplitude extraction, the adaptive determination method for hemostasis judgment threshold, the convergence guarantee mechanism for minimum effective pressure search, the linear regression estimation of exudate change rate and the three-level response strategy, the detailed steps of step-by-step pressure relief, and the differentiated parameter configuration for battlefield modes.

[0079] Example 3 This embodiment uses femoral artery injury with active bleeding caused by battlefield gunshot wounds as a scenario to fully describe the specific technical execution path of the dynamic pressure correction mechanism. It focuses on how this mechanism can achieve adaptive pressure modulation under the condition of rapid deterioration of physiological state when the fixed step-size pressure supplementation logic cannot respond effectively.

[0080] In Phase S1, after the battlefield first aid mode is activated, the central control module 18 commands the pneumatic pressurization pump 11 to inflate at the maximum rate. The signal collected by the first PPG sensor 21, after bandpass filtering, calculates A1(t) = 0.42, which is much higher than Ah = 0.05, indicating continuous perfusion of the femoral artery and insufficient current pressure. The central control module 18 continuously inflates at ΔP1 = 15 mmHg. When the intraluminal pressure P = 165 mmHg, A1(t) = 0.03, which is lower than Ah = 0.05, and the duration meets Tw = 8 seconds. The hemostasis assessment is passed, and the result is recorded. =165mmHg, enter S2.

[0081] In phase S2, the central control module 18 initiates a pressure relief iteration with ΔP2 = 5 mmHg. After the first pressure relief, P = 160 mmHg, A1(t) = 0.03, B1 = 0.10, and neither termination condition is triggered. In the second iteration, P = 155 mmHg, A1(t) = 0.04, B1 = 0.12, and the process continues. In the third iteration, P = 150 mmHg, A1(t) = 0.06, exceeding Ah = 0.05, thus triggering the termination condition. The central control module 18 immediately closes the gas release valve 15 and commands the pneumatic pressurization pump 11 to replenish gas. =15mmHg, the intraluminal pressure rises to P=165mmHg, Pm=165mmHg is written to the maintenance pressure register and locked. This step still performs a complete search in battlefield first aid mode because the continuous bleeding pressure requirement of the femoral artery wound changes dynamically with the coagulation process, and fixing Pmax would cause unnecessary high-pressure damage after the initial coagulation is established.

[0082] Baseline establishment in phase S3; at the end of phase S2, the central control module 18 acquires PPG sensor signals and records the physiological baseline: HR0 = 112 bpm, SpO2 = 1000 mmol / L. 20 =0.96, PI0=0.85, initial value of leakage detection unit B1=0.12, and the sliding window is initialized accordingly.

[0083] The first calculation cycle of stage S3 (minute 18) is: the slope of the linear regression of the B1(t) sequence within the sliding window. =0.0045 / s, exceeding =0.004 / s, triggering the pressure compensation branch. The central control module 18 synchronously reads the current PPG signal and calculates the three normalized changes: ; ; ; Substitute into PSI(t) to calculate: ; Calculate the pressure deflection term: ; Calculate adaptive target pressure: ; The central control module 18 sends a replenishment command to the pneumatic pressurization pump 11, adjusting the internal pressure to Padj = 171.4 mmHg. After pressurization is complete, the central control module 18 updates the baseline: HR0 = 128, SpO 20 =0.93, PI0=0.71, reset the sliding window.

[0084] If the original fixed-step logic is used, the pressure compensation amount at the same trigger moment is only [missing information]. =5mmHg, the intracavitary pressure is adjusted to 170mmHg, the difference is about 1.4mmHg; however, in subsequent scenarios of rapid physiological deterioration, the difference between the two logics will be significantly amplified, as shown below.

[0085] The second calculation cycle of Phase S3 (minute 26, physiological state further deteriorates): The injured soldier exhibits characteristics of the compensatory phase of hemorrhagic shock, dB1 / dt = 0.0092 / s, exceeding... =0.010 / s boundary, calculated by central control module 18: ; ; ; ; ; ; The central control module 18 adjusts the intracavitary pressure to 183.0 mmHg, and simultaneously sends an alarm data packet via the wireless data transmission unit 26, containing the current... Estimated value PSI(t) and timestamp. If a fixed step size logic is used, the pressure compensation amount at the same time is still [value missing]. =5mmHg, the intracavitary pressure was only adjusted to 176.4mmHg, a difference of 6.6mmHg. In the case of femoral artery hypertension bleeding, this difference is enough to cause hemostasis failure.

[0086] When the patient's physiological state is stable (HR, SpO2, and PI all remain unchanged), the normalized changes in all three parameters are 0, and PSI(t) = 0. =0, =Pm, the device is maintained at the lowest effective pressure, which is completely consistent with the S2 result and does not introduce additional pressure disturbance; when That is, when all three indicators reach their maximum deterioration level, = , Since K≤1 and Padj(t)≤Pmax, the safety upper limit constraint is naturally satisfied. The two boundary conditions together ensure that the behavior of the bias term is predictable throughout the entire effective range, and there is no risk of overpressure.

[0087] The output Pm of S2 is The fixed anchor point in the calculation formula; PSI(t) achieves real-time correction of the anchor point through dynamic modulation of the available margin space (Pmax−Pm), forming a multivariable adaptive closed-loop control structure with dual feedback channels of PPG multidimensional physiological signals and effusion change rate, Pm as the dynamic anchor point, and Padj(t) as the control output. In this structure, the effusion change rate... The PSI(t) positive term is responsible for determining whether intervention is needed, while the PSI(t) positive term is responsible for determining the magnitude of the intervention. The two signal channels have clear division of labor and do not substitute for each other.

Claims

1. A hemostatic device for use on the battlefield, characterized in that, include: A pressurization unit for inflating or deflating the tourniquet; a sensing unit including at least an intracavitary pressure detection unit, a photoplethysmography (PPG) sensor, and an exudate detection unit; and a control unit electrically connected to the pressurization unit and the sensing unit, the control unit being configured to operate according to the following steps: Step S0: Working mode selection, the control unit selects between clinical mode and battlefield first aid mode based on user input or automatic injury assessment; Step S1: Hemostasis status assessment. The control unit controls the pressurization unit to inflate the tourniquet to the initial pressure P0. At the same time, the PPG sensor continuously collects the PPG signal of the tourniquet-covered area. The control unit extracts the pulsation component of the PPG signal and calculates the pulsation amplitude A(t). When A(t) is lower than the hemostasis judgment threshold Ah within the preset time window Tw, the hemostasis assessment is deemed successful; otherwise, the assessment is repeated by increasing the pressure in increments of ΔP1. If the battlefield first aid mode is in operation and the PPG signal is missing or extremely weak, the pressure will be increased directly to the safe limit Pmax and locked. Step S2: Minimum effective pressure search. In clinical mode, after hemostasis assessment is passed, the tourniquet is depressurized in small increments with a step size ΔP2. After each depressurization, wait for a stabilization time Ts and collect the PPG signal again. When A(t) exceeds the hemostasis judgment threshold Ah or the exudation detection unit signal exceeds the exudation warning lower limit, depressurization is stopped, and the current pressure plus the pressure recovery amount is used as the maintenance pressure lock. In battlefield emergency mode, this step is skipped, and the pressure determined in step S1 is used directly as the maintenance pressure Pm. Step S3: Predictive compensation for seepage. During the pressure maintenance phase, the control unit continuously acquires the signal value B(t) of the seepage detection unit at a fixed sampling period and calculates the rate of change of the seepage signal. ,when Exceeding the exudation acceleration threshold When, trigger stress compensation and issue an early warning; when Persistently exceeding the severity threshold At that time, the pressure will be rapidly increased to Pmax and an alarm message will be sent through the communication unit; Step S4: Pressurization time control, the control unit controls the total pressurization time. Accumulate, when Reaching the preset limit In this case, a stepped depressurization process is implemented; in battlefield emergency rescue mode, The severity of the injury is dynamically extended, and the duration of pressurization is reported to the external terminal in real time.

2. A battlefield hemostatic device according to claim 1, characterized in that, In step S0 of the control unit configuration, the battlefield first aid mode is activated by the wounded or rescue personnel through a single button press or preset gesture. After activation, the device automatically enters the rapid inflation process in step S1.

3. A battlefield hemostatic device according to claim 1, characterized in that, In step S1 of the control unit configuration, the method for extracting the pulsation component of the PPG signal includes: performing bandpass filtering on the acquired raw signal, extracting the periodic pulsation component corresponding to the heart rate frequency band, and using the amplitude peak-to-valley difference of the filtered signal within the time window Tw as the pulsation amplitude A(t).

4. A battlefield hemostatic device according to claim 1, characterized in that, In step S2 of the control unit configuration, the pressure decrease step size ΔP2 is smaller than the pressure increase step size ΔP1 in step S1, thereby achieving a refined search for the minimum effective blood pressure control force.

5. A battlefield hemostatic device according to claim 1, characterized in that, In step S3 of the control unit configuration, the method for calculating the rate of change of the seepage signal includes: performing linear regression on the sampling sequence of the seepage detection unit within a preset sliding time window, and using the regression slope as... The estimated value is obtained by smoothing out the interference of random noise on the calculation of the rate of change.

6. A battlefield hemostatic device according to claim 1, characterized in that, The control unit integrates the heart rate, blood oxygen, and blood perfusion index measured by the PPG sensor and uploads the monitoring data to the cloud server or the accompanying emergency terminal via the communication unit. If the cloud server does not receive data updates within a preset time window, it determines that the tourniquet may have been removed prematurely and issues a prompt.

7. A battlefield hemostatic device according to any one of claims 1 to 6, characterized in that, The tourniquet includes a first tourniquet and a second tourniquet, which correspond to the arterial injury site and the venous injury site, respectively. When the air pressure in the area corresponding to the first tourniquet reaches a first predetermined value, the control unit closes the air passage connecting to the second tourniquet, so that the gas output from the pressurization unit is only introduced into the first tourniquet to continuously increase the pressure on the arterial side.

8. A battlefield hemostatic device according to claim 1, characterized in that, It also includes a communication unit and an energy unit. The communication unit is electrically connected to the control unit and is used to send physiological monitoring data and alarm information to an external terminal or cloud server. The energy unit provides electrical energy.

9. A battlefield hemostatic device according to claim 1, characterized in that, The device also includes an audio output module for issuing alert sounds during leakage warnings and serious alarms.

10. A battlefield hemostatic device according to claim 1, characterized in that, The device also includes a display unit electrically connected to the control unit, used to display in real time the heart rate value, blood oxygen value, blood perfusion index and current tourniquet pressure value measured by the PPG sensor.

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