Cardiopulmonary resuscitation feedback device and compression parameter calibration method

Abstract

The present application relates to the technical field of medical devices, and particularly relates to a cardiopulmonary resuscitation feedback device and a compression parameter calibration method. The device comprises an outer buffer layer, an inner protective layer and a circuit board integrated with a displacement sensor assembly, a pressure sensor and a processing chip; the circuit board is arranged in the inner protective layer, and the outer buffer layer covers the inner protective layer; the inner protective layer is used for protecting the circuit board; the displacement sensor assembly comprises an accelerometer and a gyroscope; the processing chip is used for receiving the collected data of the displacement sensor assembly and the pressure sensor, performing multiple filtering, gravity direction estimation, vertical acceleration synthesis and integral correction perpendicular to the chest of a patient, combining the pressure signal of the pressure sensor and the pressure threshold to determine the effective compression period, and realizing the calculation and calibration of the CPR compression depth and the compression frequency. In the scheme, the displacement sensor assembly is integrated on the circuit board, the interference of the deformation of the rigid support on the sensor signal is eliminated, and the monitoring accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a cardiopulmonary resuscitation feedback device and a method for calibrating compression parameters. Background Technology

[0002] The depth, frequency, and quality of chest compressions during cardiopulmonary resuscitation (CPR) are key indicators determining the success rate of resuscitation. Current CPR feedback devices generally employ a "rigid support + independent sensor + multi-layer rigid connection" structure. This results in a fixed sensor layout, complex structure, high assembly costs, and monitoring accuracy is easily affected by structural deformation. Furthermore, most products rely on a single sensor and lack posture compensation, filtering, and drift correction mechanisms, failing to meet the high-precision clinical requirements.

[0003] Therefore, there is an urgent need for a cardiopulmonary resuscitation feedback device and a method for calibrating compression parameters. Summary of the Invention

[0004] To address the problem that existing CPR feedback devices generally employ a "rigid support + independent sensor + multi-layer hard connection" structure, which makes monitoring accuracy susceptible to structural deformation and lacks posture compensation, filtering, and drift correction mechanisms, thus failing to meet high-precision requirements, this invention provides a cardiopulmonary resuscitation feedback device and a method for calibrating compression parameters.

[0005] In a first aspect, embodiments of the present invention provide a cardiopulmonary resuscitation (CPR) feedback device, comprising: an outer buffer layer, an inner protective layer, and a circuit board integrating a displacement sensor assembly, a pressure sensor, and a processing chip; the circuit board is disposed within the inner protective layer, and the outer buffer layer covers the inner protective layer; the inner protective layer is used to protect the circuit board, and the outer buffer layer is used to buffer the impact force of the rescuer's chest compressions, improving the feel of the compressions; the displacement sensor assembly includes an accelerometer and a gyroscope; The processing chip is used to receive the data collected by the displacement sensor assembly and the pressure sensor, perform multiple filtering, gravity direction estimation, vertical acceleration synthesis and integral correction perpendicular to the patient's chest on the data collected by the displacement sensor assembly, and determine the effective compression cycle by combining the pressure signal and pressure threshold of the pressure sensor, thereby realizing the calculation and calibration of CPR compression depth and compression frequency.

[0006] Secondly, embodiments of the present invention provide a method for calibrating pressing parameters based on the device described in any embodiment of the specification, comprising: In response to the compressions of the rescue personnel, the processing chip uses pressure signals from pressure sensors and pressure thresholds to determine the effective compression cycle; The data collected by the displacement sensor assembly is filtered multiple times by the processing chip, gravity direction is estimated, and vertical acceleration perpendicular to the patient's chest is synthesized and integrated for correction, so as to obtain the calculation and calibration of CPR compression depth and compression frequency.

[0007] This invention provides a cardiopulmonary resuscitation (CPR) feedback device and a method for calibrating compression parameters. The displacement sensor assembly is directly integrated onto the circuit board surface, eliminating the need for independent brackets, mounting bases, or other intermediate components. This completely eliminates interference from rigid bracket deformation on the sensor signal, improving displacement monitoring accuracy. A dual-channel acquisition method using both displacement and pressure sensors is employed. Through multiple filtering processes, gravity direction estimation, and synthesis and integration correction of vertical acceleration perpendicular to the patient's chest, the compression depth is calculated. The effective compression cycle is determined by combining the pressure signal from the pressure sensor and the pressure threshold, avoiding invalid interference signals and achieving the calculation and calibration of CPR compression depth and frequency. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of a cardiopulmonary resuscitation feedback device provided in an embodiment of the present invention; Figure 2 This is a flowchart of a method for calibrating pressing parameters according to an embodiment of the present invention.

[0010] Figure label: 1. Upper shell; 2. Upper protective cover; 3. Lower protective cover; 4. Connecting wire; 5. Circuit board; 6. Lower shell; 7. Pad layer; 8. Pressure sensor. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0012] Please refer to Figure 1This invention provides a cardiopulmonary resuscitation feedback device, comprising: an outer buffer layer, an inner protective layer, and a circuit board 5 integrating a displacement sensor assembly, a pressure sensor 8, and a processing chip; the circuit board 5 is disposed within the inner protective layer, and the outer buffer layer covers the inner protective layer; the inner protective layer is used to protect the circuit board 5, and the outer buffer layer is used to buffer the impact force of the rescuer's chest compressions and improve the chest compression feel; the displacement sensor assembly includes an accelerometer and a gyroscope; The processing chip receives data from the displacement sensor assembly and the pressure sensor 8, performs multiple filtering, gravity direction estimation, vertical acceleration synthesis and integral correction perpendicular to the patient's chest on the data collected by the displacement sensor assembly, and determines the effective compression cycle by combining the pressure signal and pressure threshold of the pressure sensor 8, thereby realizing the calculation and calibration of CPR compression depth and compression frequency.

[0013] In this embodiment of the invention, existing feedback devices often install sensors independently between a rigid support or the compression part, requiring the transmission of compression force through the support. This is susceptible to interference from structural deformation, and the displacement monitoring error is generally greater than ±5mm. In this embodiment, the displacement sensor assembly is directly integrated on the circuit board surface, eliminating the need for independent supports, mounting bases, and other intermediate components. This completely eliminates the interference of rigid support deformation on the sensor signal and improves the accuracy of displacement monitoring. A dual-channel acquisition method using both displacement and pressure sensors is adopted. Through multiple filtering, gravity direction estimation, and synthesis and integration correction of vertical acceleration perpendicular to the patient's chest, the compression depth is calculated. The effective compression cycle is determined by combining the pressure signal and pressure threshold of the pressure sensor, avoiding invalid interference signals, and realizing the calculation and calibration of CPR compression depth and compression frequency.

[0014] In some embodiments, the outer buffer layer includes an upper shell 1 and a lower shell 6, which are connected by secondary injection molding or a special adhesive, and the outer buffer layer is made of a soft elastomer.

[0015] In this embodiment, the upper shell 1 and the lower shell 6 are made of at least one of silicone, TPU, and TPE, with a Shore hardness of 40A-70A. Single-layer soft rubber structures are prone to deformation, affecting the acquisition of pressure signals. In this embodiment, the outer buffer layer adopts a double-layer soft rubber structure to reduce deformation, improve the protection of the circuit board 5 and the sensor, and enhance waterproof and dustproof performance. Furthermore, double-layer structures often use rigid connections such as screws and clips, resulting in cumbersome assembly processes and low mass production yield. This embodiment uses a non-rigid connection, without screws, clips, or other rigid connecting components. During pressing, only the outer buffer layer undergoes elastic deformation, while the inner protective layer remains stable, avoiding stress impact on the internal sensor and circuit board.

[0016] In some embodiments, the inner protective layer includes an upper protective cover 2 and a lower protective cover 3, which are connected by ultrasonic welding or adhesive to form a closed cavity.

[0017] In this embodiment, the upper protective cover 2 and the lower protective cover 3 are made of rigid engineering plastic, such as ABS, PC, PS, PP, or a combination thereof, with a thickness of 1.0-1.5mm. A single-layer hard shell can easily damage the sensor and has poor waterproof and dustproof performance. This embodiment uses a double-layer protective cover to form the inner protective layer, improving safety and waterproof and dustproof performance. This embodiment uses a non-rigid connection, without screws, clips, or other rigid connecting parts. It uses ultrasonic welding or adhesive to form a closed cavity, which is waterproof and dustproof.

[0018] In some embodiments, it also includes a pad 7 disposed at the bottom of the outer buffer layer, the pad 7 being used to adhere and fix to human skin to prevent displacement during the pressing process.

[0019] In this embodiment, the padding layer 7 is made of medical-grade silicone and high-adhesion double-sided adhesive, which adheres to and fixes to human skin to prevent the device from shifting during the pressing process and improve wearing comfort. The padding layer 7 can be adjusted in size according to different body types of adults and children.

[0020] In some implementations, when the processing chip performs multiple filtering, gravity direction estimation, vertical acceleration synthesis and integration correction perpendicular to the patient's chest on the data collected by the displacement sensor assembly, and determines the effective compression cycle by combining the pressure signal and pressure threshold from the pressure sensor 8, it performs the following steps S1-S9 to calculate and calibrate the CPR compression depth and compression frequency: S1, acquire the three-axis acceleration collected by the accelerometer and the angular velocity of rotation around the three axes collected by the gyroscope; It should be noted that, in order to further improve the monitoring accuracy, it is also necessary to perform zero-point calibration and error compensation on the accelerometer, and pressure-voltage linear calibration on the pressure sensor 8 to eliminate system errors.

[0021] S2 employs a complementary filtering algorithm combining gyroscope prediction and acceleration correction to fuse the first target rotation angle around the X-axis and the second target rotation angle around the Y-axis.

[0022] In this step, the rotation angles of the first and second targets are calculated as follows: Based on the triaxial accelerations collected by the accelerometer, calculate the estimated values ​​of the first rotation angle around the X-axis and the second rotation angle around the Y-axis: In the formula, and These are the estimated values ​​of the first rotation angle around the X-axis and the second rotation angle around the Y-axis, respectively. These represent the displacement accelerations in the x, y, and z directions, respectively, collected by the accelerometer. To find the radian function, To find the expression in radians The arctangent value; Based on the angular velocities of rotation around the three axes collected by the gyroscope, the predicted values ​​of the first rotation angle around the X-axis and the second rotation angle around the Y-axis are calculated: In the formula, and These are the predicted values ​​for the first rotation angle around the X-axis and the second rotation angle around the Y-axis, respectively. and These represent the first target rotation angle around the X-axis and the second target rotation angle around the Y-axis after fusion at the previous sampling time. These are the angular velocities of rotation around the x-axis and y-axis, respectively, collected by the gyroscope. The sampling period; The fusion yields the first target rotation angle around the X-axis and the second target rotation angle around the Y-axis: In the formula, and These are the rotation angles of the first target around the X-axis and the rotation angle of the second target around the Y-axis, respectively. These are complementary filter coefficients.

[0023] S3, based on the rotation angles of the first and second targets, estimates the unit vector of the gravity direction.

[0024] S4 projects the triaxial acceleration onto the direction of gravity to synthesize a vertical acceleration perpendicular to the patient's chest.

[0025] In steps S3-S4, the unit vector of the direction of gravity is: In the formula, the unit vector of the direction of gravity is: , and These are the rotation angles of the first target around the X-axis and the rotation angles of the second target around the Y-axis, respectively. The vertical acceleration is: In the formula, Vertical acceleration, These represent the displacement accelerations in the x, y, and z directions, respectively, collected by the accelerometer. This is the acceleration due to gravity.

[0026] In this embodiment, a complementary filtering algorithm combining gyroscope prediction and acceleration correction is used to estimate the direction of gravity, eliminate the directional error caused by device tilt, and project the three-axis acceleration data onto a direction perpendicular to the patient's chest through an attitude matrix to synthesize vertical acceleration. The direction of the acceleration component calculated subsequently is always perpendicular to the patient's chest, ensuring that the acceleration calculated subsequently is only related to the compression depth.

[0027] S5 performs low-pass and high-pass filtering on the vertical acceleration to obtain the filtered vertical acceleration.

[0028] In this step, the filtered vertical acceleration is calculated as follows: First, perform a low-pass filter on the filtered vertical acceleration: In the formula, This refers to the vertical acceleration after low-pass filtering. This is the vertical acceleration after the previous filtering. For this vertical acceleration, These are the low-pass filter coefficients. For low-pass cutoff frequency, The sampling period; Then, high-pass filter is applied to the low-pass filtered vertical acceleration to obtain the filtered vertical acceleration: In the formula, This is the filtered vertical acceleration. This refers to the vertical acceleration after low-pass filtering. This is the vertical acceleration after the previous filtering. This is the vertical acceleration after the previous low-pass filtering. These are the high-pass filter coefficients. This is the Qualcomm cutoff frequency. The sampling period.

[0029] In this embodiment, IIR high-pass and low-pass filters are used to process the synthesized vertical acceleration. The low-pass filter suppresses high-frequency hand tremor noise, and the high-pass filter eliminates low-frequency drift of the accelerometer.

[0030] S6, determine whether the pressure signal exceeds the pressure threshold. If it does, determine that CPR compression has started and start recording the filtered vertical acceleration. S7 continuously monitors the pressure signal, and when it falls below the pressure threshold, it determines that the current CPR compression cycle has ended. S8 performs trapezoidal integration on the filtered vertical acceleration at the start of CPR compression, continuously calculates the compression displacement, and eliminates integral drift error by zeroing at the end of each CPR compression cycle.

[0031] In this step, the compression displacement is calculated as follows: In the formula, and These are the current press speed and the previous press speed, respectively. This is the filtered vertical acceleration. This is the vertical acceleration after the previous filtering. and These are the current press displacement and the previous press displacement, respectively. The sampling period.

[0032] S9 calculates the pressing depth based on the peak and valley values ​​of the pressing displacement, and converts the pressing frequency based on the start and end time interval of the two most recent pressings, so as to output the pressing depth and pressing frequency.

[0033] The calculated compression depth and frequency parameters are output to the AED host via connection line 4, and effective compression prompts are given according to clinical standards.

[0034] In summary, traditional feedback devices suffer from insufficient algorithm accuracy, relying on a single sensor for data acquisition, lacking attitude compensation and effective filtering, resulting in severe integral drift and significant accumulation of compression errors over long periods. This embodiment employs a dual-channel acquisition method using a displacement sensor and a pressure sensor. Through multi-step filtering, gravity direction estimation, and integral correction, it achieves accurate calculation and calibration of CPR compression depth and frequency. Simultaneously, it determines the effective compression cycle through a pressure threshold, avoiding invalid interference signals, which can greatly improve the accuracy of the cardiopulmonary resuscitation feedback device.

[0035] like Figure 2 As shown, embodiments of the present invention also provide a method for calibrating pressing parameters based on the device of any embodiment of this specification, comprising: 200, responding to the compressions of the rescue personnel, uses the processing chip to determine the effective compression cycle based on the pressure signal from the pressure sensor and the pressure threshold; 202. The data collected by the displacement sensor component is filtered multiple times, gravity direction is estimated, and vertical acceleration perpendicular to the patient's chest is synthesized and integrated for correction using the processing chip, so as to obtain the calculation and calibration of CPR compression depth and compression frequency.

[0036] Since the above method is based on the same concept as the device embodiment of the present invention, the specific details can be found in the description of the device embodiment of the present invention, and will not be repeated here.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0038] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as ROM, RAM, magnetic disk, or optical disk.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cardiopulmonary resuscitation feedback device, characterized in that, include: The system comprises an outer buffer layer, an inner protective layer, and a circuit board integrating a displacement sensor assembly, a pressure sensor, and a processing chip; the circuit board is disposed within the inner protective layer, and the outer buffer layer covers the inner protective layer; the inner protective layer protects the circuit board, and the outer buffer layer cushions the impact force of the rescue personnel's pressing action, improving the pressing feel; the displacement sensor assembly includes an accelerometer and a gyroscope. The processing chip is used to receive the data collected by the displacement sensor assembly and the pressure sensor, perform multiple filtering, gravity direction estimation, vertical acceleration synthesis and integral correction perpendicular to the patient's chest on the data collected by the displacement sensor assembly, and determine the effective compression cycle by combining the pressure signal and pressure threshold of the pressure sensor, so as to realize the calculation and calibration of CPR compression depth and compression frequency. The processing chip, when performing multiple filtering, gravity direction estimation, vertical acceleration synthesis and integration correction perpendicular to the patient's chest, and combining the pressure signal and pressure threshold from the pressure sensor to determine the effective compression cycle, calculates and calibrates CPR compression depth and frequency, and is used for: The accelerometer collects the three-axis acceleration, and the gyroscope collects the angular velocity of rotation around the three axes. A complementary filtering algorithm combining gyroscope prediction and acceleration correction is used to fuse the first target rotation angle around the X-axis and the second target rotation angle around the Y-axis. Based on the rotation angles of the first target and the second target, estimate the unit vector of the gravity direction; The triaxial acceleration is projected onto the direction of gravity to synthesize a vertical acceleration perpendicular to the patient's chest. The vertical acceleration is subjected to low-pass and high-pass filtering to obtain the filtered vertical acceleration. Determine if the pressure signal exceeds the pressure threshold. If it does, determine that CPR compression has started and begin recording the filtered vertical acceleration. The pressure signal is continuously monitored, and when it falls below the pressure threshold, the CPR compression cycle is considered to be over. At the start of CPR compressions, the filtered vertical acceleration is integrally calculated using a trapezoidal method, and the compression displacement is continuously calculated. At the end of each CPR compression cycle, the integral drift error is eliminated by zeroing correction. The pressing depth is calculated based on the peak and valley values ​​of the pressing displacement, and the pressing frequency is calculated based on the start and end time interval of the two most recent pressings, so as to output the pressing depth and the pressing frequency. The unit vector of the direction of gravity is: In the formula, the unit vector of the direction of gravity is: , and These are the rotation angles of the first target around the X-axis and the rotation angles of the second target around the Y-axis, respectively. The vertical acceleration is: In the formula, Vertical acceleration, These are the displacement accelerations in the x, y, and z directions collected by the accelerometer, respectively. It is the acceleration due to gravity; The filtered vertical acceleration is calculated as follows: First, perform a low-pass filter on the filtered vertical acceleration: In the formula, This refers to the vertical acceleration after low-pass filtering. This is the vertical acceleration after the previous filtering. For this vertical acceleration, These are the low-pass filter coefficients. For low-pass cutoff frequency, The sampling period; Then, high-pass filter is applied to the low-pass filtered vertical acceleration to obtain the filtered vertical acceleration: In the formula, This is the filtered vertical acceleration. This refers to the vertical acceleration after low-pass filtering. This is the vertical acceleration after the previous filtering. This is the vertical acceleration after the previous low-pass filtering. These are the high-pass filter coefficients. This is the Qualcomm cutoff frequency. The sampling period; The method for calculating the compression displacement is as follows: In the formula, and These are the current press speed and the previous press speed, respectively. This is the filtered vertical acceleration. This is the vertical acceleration after the previous filtering. and These are the current press displacement and the previous press displacement, respectively. The sampling period.

2. The apparatus according to claim 1, characterized in that, The outer buffer layer includes an upper shell and a lower shell, which are connected by secondary injection molding or a special adhesive. The outer buffer layer is made of a soft elastomer.

3. The apparatus according to claim 1, characterized in that, The inner protective layer includes an upper protective cover and a lower protective cover, which are connected by ultrasonic welding or adhesive to form a closed cavity.

4. The apparatus according to claim 1, characterized in that, Also includes: The padding layer located at the bottom of the outer buffer layer is used to adhere and fix to human skin to prevent displacement during the pressing process.

5. The apparatus according to claim 1, characterized in that, The rotation angles of the first target and the second target are calculated as follows: Based on the triaxial accelerations collected by the accelerometer, calculate the estimated first rotation angle around the X-axis and the estimated second rotation angle around the Y-axis: In the formula, and These are the estimated values ​​of the first rotation angle around the X-axis and the second rotation angle around the Y-axis, respectively. These are the displacement accelerations in the x, y, and z directions collected by the accelerometer, respectively. To find the radian function, To find the expression in radians The arctangent value; Based on the angular velocities of rotation around the three axes collected by the gyroscope, the predicted values ​​of the first rotation angle around the X-axis and the second rotation angle around the Y-axis are calculated: In the formula, and These are the predicted values ​​for the first rotation angle around the X-axis and the second rotation angle around the Y-axis, respectively. and These represent the first target rotation angle around the X-axis and the second target rotation angle around the Y-axis after fusion at the previous sampling time. These are the angular velocities of rotation around the x-axis and y-axis collected by the gyroscope, respectively. The sampling period; The fusion yields the first target rotation angle around the X-axis and the second target rotation angle around the Y-axis: In the formula, and These are the rotation angles of the first target around the X-axis and the rotation angle of the second target around the Y-axis, respectively. These are complementary filter coefficients.

6. A method for calibrating pressing parameters based on the device according to any one of claims 1-5, characterized in that, include: In response to the compressions of the rescue personnel, the processing chip uses pressure signals from pressure sensors and pressure thresholds to determine the effective compression cycle; The data collected by the displacement sensor assembly is filtered multiple times by the processing chip, gravity direction is estimated, and vertical acceleration perpendicular to the patient's chest is synthesized and integrated for correction, so as to obtain the calculation and calibration of CPR compression depth and compression frequency.

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