Noninvasive pulmonary edema monitoring device with limb circumference measuring function

Abstract

The invention relates to the field of medical equipment, in particular to a noninvasive pulmonary edema monitoring device with a limb circumference measuring function and a capacity evaluation method. Comprising a flexible contact unit, an elastic bandage, a pressure-sensitive rubber ring and a fixing frame are arranged on the flexible contact unit, the fixing frame is an elastic silica gel frame, a lung monitoring device and a limb measuring device can be placed in the fixing frame, the lung monitoring device is of a flexible patch structure, the limb measuring device comprises a pi ruler and a reading device, and the lung monitoring device is of a multi-layer structure. The upper layer is a fabric surface, the middle layer is a flexible patch circuit, and the bottom layer is a monitoring contact chip; the lung monitoring device and the limb measuring device are connected with the host, the host is of a handheld type or a computer type and comprises a display screen and an operation screen, the handheld type is of an L-shaped overall structure, the handheld type operation screen is of a < = structure, and a handwriting pen is arranged on the side edge of the bottom of the handheld type operation screen. The host system intelligently fuses monitored lung impedance data and limb girth changes to form comprehensive evaluation indexes of pulmonary edema.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to a non-invasive pulmonary edema monitoring device and volume assessment method that includes limb circumference measurement function. Background Technology

[0002] Fluid management is a core aspect of treatment for patients undergoing hemodialysis, chronic heart failure, and other similar procedures. Fluid overload is a major cause of hypertension, cardiovascular events, and recurrent hospitalizations. Therefore, accurate and convenient assessment of a patient's fluid status is crucial. However, in current clinical monitoring scenarios, the methods for monitoring limb circumference and pulmonary edema, core indicators for assessing fluid balance, have significant shortcomings: limb circumference measurements are currently mostly done manually using handheld measuring tapes, which increases the risk of cross-infection; secondly, they cannot visually indicate changes in edema. Lung monitoring relies primarily on lung ultrasound CT scans or invasive procedures, which are often performed by untrained imaging specialists in primary care settings. Furthermore, lung and limb measurements are separated, requiring different medical staff to operate different equipment, leading to asynchronous data recording and potentially biased clinical judgment.

[0003] To address the aforementioned technical deficiencies, a non-invasive pulmonary edema monitoring device and volume assessment method incorporating limb circumference measurement function are provided. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a non-invasive pulmonary edema monitoring device and volume assessment method with limb circumference measurement function, comprising a flexible contact unit, wherein the flexible contact unit has an elastic band, a pressure-sensitive rubber ring and a fixing frame, wherein the fixing frame is an elastic silicone frame, and a lung monitoring device and a limb measuring device can be placed inside the fixing frame, wherein the lung monitoring device is a flexible patch structure, and the limb measuring device includes a π ruler and a reading device, wherein the limb measuring device can also be used independently.

[0005] The lung monitoring device has a multi-layer structure, with the upper layer being a fabric surface, the middle layer being a flexible patch circuit, and the bottom layer being a monitoring contact piece.

[0006] The π ruler is made of leather and has its head designed on the ruler box. The tail end has a magnetic piece. The ruler box has grooves on both sides. The reading device has a sliding buckle. The sliding buckle clamps the head end of the π ruler and moves it back and forth on the groove.

[0007] The reading device has a calculation display screen, a scale screen, and a magnetic clasp. The calculation display screen displays real-time measurement values ​​and increments / decreases. The scale screen records the distance and position of the sliding buckle as it moves forward and retracts. The specific distance is displayed on the calculation display screen. The magnetic clasp is attracted to the magnetic clasp at the end of the π ruler.

[0008] The lung monitoring device and limb measurement device are connected to a main unit. The main unit is available in handheld and computer-based versions, including a display screen and an operating screen. The handheld version has an L-shaped overall structure, and the operating screen has a ≤-shaped structure. A stylus is located on the bottom side of the handheld operating screen. The main unit can be used with multiple lung monitoring devices and limb measurement devices, allowing multiple patients to take turns using the same main unit, thus improving equipment utilization.

[0009] The lung monitoring device and reading device have a Type-C magnetic charging port and a battery compartment. The elastic silicone frame has strap holes and a pull cord. The lung monitoring device has corresponding mounting holes.

[0010] The flexible contact unit is made of sterile, skin-friendly fabric, which can also be coated with medical pressure-sensitive adhesive. It conforms closely to the curves of the human chest and back, making it suitable for long-term wear and monitoring. The elastic strap has double-sided buckles to adjust the size of the strap.

[0011] A non-invasive pulmonary edema monitoring device and volume assessment method with limb circumference measurement function are disclosed. The volume assessment method involves the host system intelligently fusing monitored lung impedance data with limb circumference changes to form a comprehensive assessment index for pulmonary edema. Based on clinical research, the occurrence of pulmonary edema is closely related to lung fluid content and the degree of limb edema. Comprehensive analysis of these two data sources can improve the accuracy and sensitivity of pulmonary edema assessment. The specific method is as follows: The lung monitoring device measures the pleural fluid level using bioelectrical impedance analysis. The software system converts the acquired impedance signal into an extravascular lung water index (EVLWI). The normal reference value for EVLWI is 3.0-7.0 mL / kg. When EVLWI exceeds 7.0 mL / kg, it indicates pulmonary edema and signifies the severity of the condition. The limb measurement device acquires limb circumference change data through a π-ruler and reading device. The software system correlates the circumference change rate with volume overload. Clinical studies have shown that a weight gain of 2 kg or a sudden increase in limb circumference of more than 10% within a short period (≤3 days) can be used as a diagnostic indicator of latent edema. The specific implementation method for linking the rate of change in circumference with capacity load is as follows:

[0012] Data standardization: The lung impedance data and limb circumference data are processed separately and mapped to the [0,1] interval to eliminate dimensional differences.

[0013] Weighting: Based on clinical research results, appropriate weights are assigned to the two data sources. Generally, pulmonary impedance data reflects a direct indicator of pulmonary edema, and its weight can be set to 70%; limb circumference data reflects systemic volume overload, and its weight can be set to 30%. The weighting coefficients can be dynamically adjusted according to individual patient characteristics and changes in their condition.

[0014] Threshold setting: Based on clinical consensus, a pulmonary edema warning threshold is set. When the comprehensive assessment indicators exceed the threshold, the software system automatically triggers an alarm, prompting medical staff to take intervention measures.

[0015] Etiological analysis: By analyzing the patterns of change in pulmonary impedance data and limb circumference data, different etiologies of pulmonary edema can be distinguished. For example, cardiogenic pulmonary edema is usually characterized by a simultaneous increase in both pulmonary impedance and limb circumference; non-cardiogenic pulmonary edema may present with increased pulmonary impedance but no significant change in limb circumference.

[0016] Multi-Patient Management: The software supports simultaneous monitoring and management of data from multiple patients. The left sidebar is designed as a tag list, with each patient represented by a virtual avatar tag. Clicking on a tag switches to that patient's monitoring interface. The tags dynamically change color based on the patient's status (red - alert, yellow - pending, green - normal), facilitating quick identification of patient status by medical staff. The top of the interface displays a list of currently connected devices, indicating their location (chest / back / limbs) and connection status, supporting quick switching and status viewing. The software system integrates multiple physiological parameters such as ECG, blood oxygen, and body temperature, providing a comprehensive patient health assessment. This enhances the system's ability to identify complex conditions, providing more comprehensive support for clinical decision-making.

[0017] Multi-device collaborative management: The software system supports multiple monitoring devices connecting to the same host, enabling efficient monitoring and management of multiple patients through data rotation. The software system manages the connection status of multiple monitoring devices via the USB composite device protocol. Each device should be assigned a unique PID / VID, and data packet grouping and reassembly are implemented through the USB forwarding layer protocol to ensure the reliability and real-time performance of multi-device data transmission. The host supports simultaneous connection of multiple devices, using RFID or QR code to identify data from different patients, achieving automatic data correlation and management.

[0018] Telemedicine support: The software system can be expanded into a remote monitoring platform, allowing doctors to remotely view patient data and provide intervention suggestions. The monitoring platform can also interface with hospital information systems (HIS) and electronic medical records (EMR) to achieve automatic data integration and analysis.

[0019] Advantages of this invention:

[0020] This invention achieves non-contact, precise limb circumference measurement and convenient, non-invasive monitoring of pulmonary edema through innovative hardware construction. It also enables automatic correlation of the two types of monitoring data through a single data terminal, thereby providing objective and comprehensive assessment of body fluid status for clinical use, improving monitoring efficiency and decision-making accuracy, and meeting the routine usage needs of clinical nursing scenarios such as dialysis centers and wards.

[0021] The lung monitoring device breaks through the limitations of traditional static imaging methods like CT and MRI, enabling portable, bedside, and visualized monitoring. The limb measurement device combines a π-ruler and a reading device to achieve precise, non-contact limb circumference measurement. This design avoids the inconvenience and errors of traditional measurement methods. The main unit offers both handheld and computer-based terminal options, both equipped with displays and operating screens, facilitating use by medical staff in various scenarios. Furthermore, the main unit system supports automatic data correlation and analysis, significantly improving diagnostic efficiency and accuracy.

[0022] The combination of a non-invasive pulmonary edema monitoring device and its supporting software system provides accurate assessment and management for early warning, dynamic monitoring, and volume management of pulmonary edema. Compared with traditional pulmonary edema monitoring methods, this system has advantages such as being non-invasive, real-time, and accurate, and can be applied to various clinical scenarios such as emergency assessment, inpatient monitoring, and discharge follow-up. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the lung effusion monitoring device of the present invention;

[0025] Figure 3 This is a schematic diagram of the π ruler in use according to the present invention;

[0026] Figure 4 This is a bottom view of the reading device of the present invention. Detailed Implementation

[0027] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figures 1-4 The present invention discloses a non-invasive pulmonary edema monitoring device and volume assessment method with limb circumference measurement function, comprising a flexible contact unit (1), which is made of fabric and can be cut to shape as needed. The flexible contact unit (1) has an elastic strap (11), a pressure-sensitive adhesive ring (12), and a fixing frame (13). The flexible contact unit (1) is made of sterile skin-friendly fabric and can also be coated with medical pressure-sensitive adhesive, which can fit closely to the curve of the human chest and back and is suitable for long-term wear monitoring. The elastic strap (11) has double buckles to adjust the size of the strap.

[0029] The fixing frame (13) is an elastic silicone frame. A lung monitoring device (2) can be installed inside the fixing frame (13). The lung monitoring device (2) is a flexible patch structure. The fixing frame (13) has strap holes and a pull rope (14). The lung monitoring device (2) has corresponding mounting holes. The device can be tied to the fixing frame with a strap, and then the tightness can be adjusted with the pull rope (14) to adapt to patients of different body types.

[0030] like Figure 2 As shown, the lung monitoring device (2) has a multi-layer structure, with the upper layer being a fabric surface (21), the middle layer being a flexible patch circuit (22), and the bottom layer being a monitoring contact piece (23). The flexible patch circuit (22) has an MCU and a power supply line, which is connected to the Type-C magnetic interface (24) and the battery box (25).

[0031] like Figure 1 and 3 The limb measuring device shown in Figure 4 includes a π ruler (3) and a reading device (31). The π ruler (3) is made of leather and has its head designed on a ruler box (32) and its tail has a magnetic absorbing piece (33). The ruler box (32) has sliding grooves (32-1) on both sides. The reading device (31) has a sliding buckle (31-1). The sliding buckle (31-1) clamps the head of the π ruler (3) and moves it back and forth on the sliding groove (32-1).

[0032] The reading device (31) has a calculation display screen (31-2), a scale screen (31-3), and a magnetic clasp (33). The calculation display screen (31-2) displays real-time measurement values ​​and increments / decreases. The scale screen (31-3) records the distance and position of the sliding buckle as it moves forward and retracts, and displays the specific distance on the calculation display screen (31-2). The magnetic clasp is attracted to the magnetic clasp at the end of the π ruler. The bottom of the reading device (31) has a Type-C magnetic charging interface (24) and a battery box (25), with a built-in circuit board.

[0033] When using the π ruler (3), pull the magnetic tab (33) at the end to stretch the π ruler (3) around the patient's limb being measured. Then, gently press down the sliding buckle (31-1) to clamp the two sides of the π ruler (3). After the sensor (32-1) on the ruler box (32) senses the pressing action, the display value on the calculation display (31-2) is cleared to zero. Then, the magnetic tab (33) at the end is attracted and fixed to the magnetic tab (33) on the reading device (31). The surface of the calculation display (31-2) displays the initial real-time measurement circumference value. If the π ruler feels loose, move the sliding buckle (31-1) backward. If the π ruler feels too tight, move the sliding buckle (31-1) forward. The scale screen (31-3) records the specific distance moved forward and backward. The surface of the calculation display (31-2) updates the latest circumference value and also records the specific increase or decrease in the forward and backward distance. This facilitates intuitive judgment by medical staff.

[0034] The design of this π ruler (3) has great advantages. First, the patient's initial real-time measurement of the circumference remains fixed. If there is swelling or subsidence, the specific circumference of the swelling can be shown by simply adjusting the tightness of the ruler box (32) at the beginning of the π ruler. The π ruler (3) can be used by attaching it to the flexible contact unit (1) with double-sided adhesive tape (for those with sensitive skin) or by using it alone.

[0035] The lung monitoring device (2) and limb measurement device are connected to the host (4) via Bluetooth or wired connection. The host (4) is available in handheld and computer versions, including a display screen (41) and an operation screen (42). The handheld version is convenient for use during ward rounds, while the computer version can be placed at the bedside to continuously monitor pulmonary edema data. The host (4) can be paired with multiple sets of lung monitoring devices (2) and limb measurement devices, allowing multiple patients to take turns using the same host, thus improving equipment utilization. The host system has an automatic interpretation and assessment function similar to the Swiss-system cardiopulmonary function tester, enabling intelligent analysis and interpretation of data, significantly improving diagnostic efficiency and accuracy. Figure 1 The handheld device shown has an L-shaped overall structure. The handheld operation screen (42) has a ≤ structure. The handheld operation screen (42) has a stylus (43) on the bottom side for the convenience of medical staff.

[0036] A non-invasive pulmonary edema monitoring device and volume assessment method with limb circumference measurement function are disclosed. The volume assessment method involves the host system intelligently fusing monitored lung impedance data with limb circumference changes to form a comprehensive assessment index for pulmonary edema. Based on clinical research, the occurrence of pulmonary edema is closely related to lung fluid content and the degree of limb edema. Comprehensive analysis of these two data sources can improve the accuracy and sensitivity of pulmonary edema assessment. The specific method is as follows: The lung monitoring device measures the pleural fluid level using bioelectrical impedance analysis. The software system converts the acquired impedance signal into an extravascular lung water index (EVLWI). The normal reference value for EVLWI is 3.0-7.0 mL / kg. When EVLWI exceeds 7.0 mL / kg, it indicates pulmonary edema and signifies the severity of the condition. The limb measurement device acquires limb circumference change data through a π-ruler and reading device. The software system correlates the circumference change rate with volume overload. Clinical studies have shown that a weight gain of 2 kg or a sudden increase in limb circumference of more than 10% within a short period (≤3 days) can be used as a diagnostic indicator of latent edema. The specific implementation path is as follows:

[0037] Data standardization: The lung impedance data and limb circumference data were normalized and mapped to the [0,1] interval to eliminate dimensional differences.

[0038] Weighting: Based on clinical research results, appropriate weights are assigned to the two data sources. Generally, pulmonary impedance data reflects a direct indicator of pulmonary edema, and its weight can be set to 70%; limb circumference data reflects systemic volume overload, and its weight can be set to 30%. The weighting coefficients are dynamically adjusted according to individual patient characteristics and changes in their condition.

[0039] Threshold setting: Based on clinical consensus, a pulmonary edema warning threshold is set. When the comprehensive assessment indicators exceed the threshold, the software system automatically triggers an alarm, prompting medical staff to take intervention measures.

[0040] Etiological analysis: By analyzing the patterns of change in pulmonary impedance data and limb circumference data, different etiologies of pulmonary edema can be distinguished. For example, cardiogenic pulmonary edema is usually characterized by a simultaneous increase in both pulmonary impedance and limb circumference; non-cardiogenic pulmonary edema may present with increased pulmonary impedance but no significant change in limb circumference.

[0041] Multi-Patient Management: The software supports simultaneous monitoring and management of data from multiple patients. The left sidebar is designed as a tag list, with each patient represented by a virtual avatar tag. Clicking on a tag switches to that patient's monitoring interface. The tags dynamically change color based on the patient's status (red - alert, yellow - pending, green - normal), facilitating quick identification of patient status by medical staff. The top of the interface displays a list of currently connected devices, indicating their location (chest / back / limbs) and connection status, supporting quick switching and status viewing. The software system integrates multiple physiological parameters such as ECG, blood oxygen, and body temperature, providing a comprehensive patient health assessment. This enhances the system's ability to identify complex conditions, providing more comprehensive support for clinical decision-making.

[0042] Multi-device collaborative management: The software system supports multiple monitoring devices connecting to the same host, enabling efficient monitoring and management of multiple patients through data rotation. The software system manages the connection status of multiple monitoring devices via the USB composite device protocol. Each device should be assigned a unique PID / VID, and data packet grouping and reassembly are implemented through the USB forwarding layer protocol to ensure the reliability and real-time performance of multi-device data transmission. The host supports simultaneous connection of multiple devices, using RFID or QR code to identify data from different patients, achieving automatic data correlation and management.

[0043] Telemedicine support: The software system can be expanded into a remote monitoring platform, allowing doctors to remotely view patient data and provide intervention suggestions. The monitoring platform can also interface with hospital information systems (HIS) and electronic medical records (EMR) to achieve automatic data integration and analysis.

[0044] This device has broad clinical application value, allowing medical staff to measure two indicators at the bedside in the dialysis center without having to travel back and forth to change measuring tapes and ultrasound equipment, significantly saving operation time. Both device modules are connected to the same data terminal, and the data is automatically matched with timestamps and integrated, eliminating the need for manual recording and entry by medical staff, avoiding errors and omissions in manual recording, and providing doctors with more reliable data for fluid assessment. In intensive care settings such as ICU and CCU, it can continuously monitor the trend of pulmonary edema changes and assist in assessing the efficacy of dehydration drugs. The combination of the software system and the non-invasive pulmonary edema monitoring device can be applied to various clinical scenarios, including emergency assessment, inpatient monitoring, and discharge follow-up. In different scenarios, the software system provides corresponding functions and interfaces to support medical staff's decision-making and intervention.

[0045] In the emergency department, the software system provides rapid alarm and diagnostic support functions. When patients exhibit symptoms of acute pulmonary edema such as difficulty breathing, orthopnea, and coughing up pink frothy sputum, medical staff can quickly connect the device for monitoring. The software system automatically analyzes pulmonary impedance and limb circumference data, calculates EVLWI values, assesses the severity of pulmonary edema, and prompts medical staff to take appropriate measures through a tiered alarm mechanism. In emergency assessment, the software system emphasizes alarm functions and rapid diagnostic support to help medical staff make correct judgments in a short time.

[0046] During hospitalization, the software system provides long-term trend analysis and volume management support. Healthcare professionals can periodically connect devices to monitor patients, and the software system automatically records the data, generating long-term trend graphs to help healthcare professionals assess treatment effectiveness and changes in patient condition. The software system also provides volume overload assessment capabilities, analyzing EVLWI and limb circumference changes to determine if the patient needs adjustments to fluid intake or medication. In inpatient monitoring, the software system emphasizes trend analysis and volume management functions to help healthcare professionals develop personalized treatment plans.

[0047] During the post-discharge follow-up phase, the software system provides remote monitoring and early warning functions. Patients can use a home-use monitoring device for daily monitoring, and the software system transmits the data to the hospital server via a wireless network. Medical staff can remotely view the patient's data, promptly detect changes in their condition, and provide intervention. The software system also provides patient education and self-management support functions to help patients understand the early symptoms and coping strategies of pulmonary edema, thereby improving their self-management abilities.

[0048] Implementation Case: The above methods, through evidence-based practice, improved the capacity for volume management in MHD patients and the collaborative abilities of healthcare professionals. This study compared the differences in interdialysis weight gain, systolic blood pressure, diastolic blood pressure, and edema levels between two groups (control group and observation group). Simultaneously, it compared the healthcare professionals' awareness of evidence regarding volume management before and after the practice. Results showed that after intervention, the observation group experienced significantly lower interdialysis weight gain, systolic blood pressure, diastolic blood pressure, and edema levels compared to the control group. The observation group also showed significantly higher scores on the Hemodialysis Volume Management Behavior Scale and the General Self-Efficacy Scale compared to the control group. Furthermore, the healthcare professionals' awareness of evidence regarding volume management significantly improved after the evidence-based practice. Evidence-based practice of hemodialysis volume management, based on optimal evidence, can improve the volume status of MHD patients and reduce the incidence of complications such as hypertension and cardiovascular events.

[0049] Reference: Evidence-based practice research on volume management in maintenance hemodialysis patients, https: / / link.cnki.net / urlid / 50.1129.R.20250819.1801.002

[0050] Authors: Xu Lijun, Shang Zhengying, Pang Miaonan, Zhang Xianghui.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-invasive pulmonary edema monitoring device with limb circumference measurement function, characterized in that: The device includes a flexible contact unit with an elastic strap, a pressure-sensitive rubber ring, and a fixing frame. The fixing frame is an elastic silicone frame, and a lung monitoring device and a limb measuring device can be placed inside the fixing frame. The lung monitoring device is a flexible patch structure, and the limb measuring device includes a ruler and a reading device. The lung monitoring device has a multi-layer structure: an upper layer of fabric surface, a middle layer of flexible patch circuit, and a bottom layer of monitoring contact pads. The lung monitoring device and limb measuring device are connected to a host computer, which is available in handheld and computer versions, including a display screen and an operating screen. The handheld version has an L-shaped overall structure, and the handheld operating screen has a ≤ structure. A stylus is located on the bottom side of the handheld operating screen.

2. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 1, characterized in that: The π ruler is made of leather and has its head designed on a ruler box. The tail end has a magnetic clasp. The ruler box has grooves on both sides. The reading device has a sliding buckle that clamps the head end of the π ruler and moves it back and forth on the groove. The reading device has a calculation display screen, a scale screen, and a magnetic clasp. The calculation display screen displays the real-time measurement value and the increase or decrease value. The scale screen records the distance and position of the sliding buckle as it moves forward and backward. The specific distance is displayed on the calculation display screen. The magnetic clasp is attracted to the magnetic clasp at the tail end of the π ruler.

3. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 1, characterized in that: The lung monitoring device and reading device have a Type-C magnetic charging port and a battery compartment. The elastic silicone frame has strap holes and a pull cord. The lung monitoring device has corresponding mounting holes.

4. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 1, characterized in that: The host unit can be equipped with multiple sets of lung monitoring devices and limb measurement devices, allowing multiple patients to take turns using the same host unit.

5. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 1, characterized in that: The flexible contact unit is made of sterile, skin-friendly fabric, which can also be coated with medical pressure-sensitive adhesive. It can fit closely to the curves of the human chest and back. The elastic strap has double buckles to adjust the size of the strap.

6. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 1, characterized in that: The host computer intelligently integrates the monitored lung impedance data with changes in limb circumference to form a comprehensive assessment index for pulmonary edema.

7. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 6, characterized in that: The specific methods for the comprehensive assessment indicators of pulmonary edema are as follows: The lung monitoring device measures the pleural fluid level using bioelectrical impedance analysis. The software system needs to convert the acquired impedance signal into extravascular lung water index (EVLWI). The normal reference value for EVLWI is 3.0-7.0 mL / kg. When EVLWI exceeds 7.0 mL / kg, it indicates pulmonary edema and represents the severity of the condition. The limb measurement device acquires limb circumference change data through a π ruler and a reading device. The software system correlates the circumference change rate with volume overload.

8. The non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 7, characterized in that: The specific method for linking the girth change rate with the capacity load is as follows: Data standardization: The lung impedance data and limb circumference data were processed separately and mapped to the [0,1] interval to eliminate dimensional differences; Weighting: Based on the results of clinical studies, assign appropriate weights to the two data sources. Generally speaking, pulmonary impedance data reflects a direct indicator of pulmonary edema, and its weight can be set to 70%; limb circumference data reflects systemic volume overload, and its weight can be set to 30%. Threshold setting: Based on clinical consensus, a pulmonary edema warning threshold is set; when the comprehensive assessment indicators exceed the threshold, the software system automatically triggers an alarm to prompt medical staff to take intervention measures; Etiological analysis: By analyzing the changing patterns of pulmonary impedance data and limb circumference data, pulmonary edema of different etiologies can be distinguished.

9. A non-invasive pulmonary edema monitoring device with limb circumference measurement function as described in claim 1, characterized in that: The host supports connecting multiple devices simultaneously, and can identify data from different patients through RFID or QR codes to achieve automatic data association and management.

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