An in-vitro blood loss monitoring device and method

Abstract

The application provides an extracorporeal blood loss monitoring device and method. The device comprises a host unit and a detection unit. During monitoring, the detection unit is in contact with a patch. The detection unit comprises an optical sensor arranged on a detection surface thereof and a plurality of electrodes flush with or protruding from the detection surface. The optical sensor and the electrodes are respectively connected to a microcontroller of the host unit. The electrodes are used to detect whether there is liquid on the patch and send the detection result to the microcontroller. The microcontroller controls the optical sensor to detect whether the liquid is blood. The extracorporeal blood loss monitoring device combines electrode detection and optical sensor detection. The electrode detection has high sensitivity and can timely find small changes. The optical sensor has strong recognition ability for blood changes. The combination of the two provides more stable baseline data, and the accuracy and reliability of extracorporeal blood loss monitoring are improved.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to an extracorporeal blood loss monitoring device and method. Background Technology

[0002] Extracorporeal blood processing devices, such as hemodialysis equipment or cell separation equipment, require access to the patient's arterial blood vessels. In extracorporeal blood processing, blood is drawn from the patient through an arterial puncture needle, processed, and then returned to the patient through a venous puncture needle.

[0003] Despite regular monitoring by hospital staff, there remains a risk that the puncture needle may slip out of the patient's blood vessel. For example, if the puncture needle and tubing are not securely fixed, or if the patient is out of control, the needle may dislodge. Arterial needle slippage can draw air into the extracorporeal circulation tubing, and can also cause blood to leak into the environment. If arterial needle slippage is not detected immediately, there is a risk of the patient bleeding to death. Even if the arterial or venous needle does not completely slip out, there is a risk of relatively large blood loss at the puncture site throughout the procedure. Rapid blood loss from dislodged venous needles can severely endanger the life of dialysis patients. During treatment, the patient's blood flow rate is approximately 250-400 ml / min, and venous needle dislodgement can lead to hemorrhagic shock in adults within about 2 minutes.

[0004] In existing technologies, pressure sensors can be used to monitor the pressure applied by the puncture needle. When the puncture needle dislodges from the blood vessel, blood flows out, causing a decrease in the pressure applied by the needle. The pressure sensor can detect this change and issue an alarm signal. However, when an intravenous needle slips out of an arteriovenous fistula, due to fixation or other reasons, the needle eventually remains at its original height. Under the influence of flow resistance at the needle hole and atmospheric pressure within the venous reservoir, it maintains a certain pressure and does not trigger an alarm. This is especially true for patients with already low venous pressure, making it even harder for the machine to detect the problem; therefore, the detection rate is only about 50%. Alternatively, a dressing can be used to fix the needle near the puncture needle, and monitoring the dressing's moisture content can determine if the needle has dislodged. However, when saline, dialysate, sweat, or other liquids soak into the dressing, it can easily cause false alarms. Summary of the Invention

[0005] In order to overcome the defects existing in the prior art, the purpose of this invention is to provide an in vitro blood loss monitoring device and method.

[0006] To achieve the above-mentioned objectives of the present invention, the present invention provides an extracorporeal blood loss monitoring device, including a main unit and a detection unit. During monitoring, the detection unit is in contact with a patch. The detection unit includes an optical sensor disposed on its detection surface and a plurality of electrodes that are flush with or protrude from the detection surface. The optical sensor and electrodes are respectively connected to the microcontroller of the main unit.

[0007] The electrode is used to detect whether there is liquid on the patch and sends the detection result to the microcontroller. The microcontroller controls the optical sensor to detect whether the liquid is blood.

[0008] This extracorporeal blood loss monitoring device combines electrode detection and optical sensors. Electrode detection has high sensitivity and can detect minute changes in a timely manner, while optical sensors have a strong ability to identify changes in blood. Together, they provide more stable baseline data, improving the accuracy and reliability of extracorporeal blood loss monitoring.

[0009] In one optional embodiment of this extracorporeal blood loss monitoring device, the optical sensor is located in the center of the detection unit, and four electrodes are arranged around the optical sensor. This optional embodiment ensures that minute changes in liquid volume in any direction can be captured and reported instantly and accurately, achieving balanced sensitivity across monitoring directions and effectively avoiding false alarms or missed alarms caused by uneven local infiltration.

[0010] In one alternative embodiment of this extracorporeal blood loss monitoring device, several electrodes include the same or different numbers of positive and negative electrodes. When there is liquid on the patch, the positive and negative electrodes become conductive. This alternative embodiment is more economical and has lower development costs.

[0011] In one alternative embodiment of this in vitro blood loss monitoring device, the main unit further includes a light source driving circuit connected to a microcontroller. The microcontroller controls the activation and deactivation of the light source driving circuit, and the light source driving circuit controls the optical sensor to emit alternating flashing red and infrared light for blood detection. This alternative embodiment uses alternating detection of red and infrared light, further improving the accuracy of blood detection.

[0012] In one alternative embodiment of the extracorporeal blood loss monitoring device, the main unit further includes a power control circuit and a button detection circuit; the power control circuit includes a first transistor and a second MOSFET, and the button detection circuit includes a second transistor.

[0013] The power switch is electrically connected between the voltage output terminal of the power module and the power interface of the microcontroller. The voltage output terminal of the power module is also connected to the source of the second MOSFET. The drain of the second MOSFET is connected to the power interface of the microcontroller. The gate of the second MOSFET is connected to the collector of the first transistor. The base of the first transistor is connected to a signal output terminal of the microcontroller. The emitter of the first transistor is grounded.

[0014] The power switch is also electrically connected between the voltage output terminal of the power module and the base of the second transistor. The emitter of the second transistor is grounded, and its collector is connected to a signal input terminal of the microcontroller.

[0015] This alternative solution features a simple structure, ingenious circuit design, and reduces the number of buttons required.

[0016] In one alternative embodiment of this in vitro blood loss monitoring device, the microcontroller is communicatively connected to the main control device and sends monitoring information to the main control device.

[0017] This invention also proposes an in vitro blood loss monitoring method, based on the above-mentioned in vitro blood loss monitoring device, comprising the following steps:

[0018] Real-time monitoring to detect the presence of liquid at the application site;

[0019] When liquid is detected at the application site, the optical sensor is triggered to detect whether the liquid is blood.

[0020] Furthermore,

[0021] The electrodes perform real-time liquid detection. If the signal detected by the electrodes reaches the humidity threshold, it is determined that there is liquid at the application site. The microcontroller then activates the light source drive circuit and the light sensor, causing the optical sensor to emit alternating flashing red and infrared light to detect whether the liquid is blood.

[0022] Furthermore,

[0023] When the signal detected by the electrode does not reach the humidity threshold, the alarm is turned off, the light source drive circuit is turned off, and the light sensor is turned off.

[0024] When the electrode detection signal reaches the humidity threshold and the liquid detected is blood, the control alarm will sound, the indicator light will flash, and the microcontroller will communicate with the main control device to send alarm information. When the liquid detected is not blood, the microcontroller will communicate with the main control device to send warning information.

[0025] When an alarm occurs, the microcontroller monitors the signal collected by the optical sensor in real time. If the liquid continuously detects blood, the current alarm status is maintained; if the liquid continuously detects non-blood, a warning message is sent; if the signal continuously detected by the electrode does not reach the humidity threshold, the alarm is deactivated.

[0026] This in vitro blood loss monitoring method possesses all the advantages of the aforementioned in vitro blood loss monitoring devices.

[0027] The beneficial effects of this invention are:

[0028] This invention combines electrode detection and an optical sensor. The electrode detection has high sensitivity, enabling timely detection of minute changes; the optical sensor has a strong ability to recognize changes in blood. Together, they provide more stable baseline data, improving the accuracy and reliability of in vitro blood loss monitoring. Furthermore, this invention has a more compact and lightweight structure; it can also operate with low power consumption and has a long battery life.

[0029] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0031] Figure 1 This is a principle block diagram of Embodiment 1;

[0032] Figure 2 This is a schematic diagram of the main unit structure;

[0033] Figure 3 This is a schematic diagram of the detection department structure;

[0034] Figure 4 This is a schematic diagram of the electrode distribution;

[0035] Figure 5 This is a schematic diagram of the circuit connections between the key detection circuit, the power module, and the power control circuit.

[0036] Figure 6 This is a flowchart illustrating Example 2;

[0037] Figure 7 This is a schematic diagram of the alarm deactivation process. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0039] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0040] Example 1

[0041] like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment provides an extracorporeal blood loss monitoring device, which includes a main unit and a detection unit. The main unit and the detection unit are electrically connected by a cable. During monitoring, the detection unit comes into contact with the dressing. Wherein, as... Figure 3 As shown, the detection unit includes a detection housing, an optical sensor disposed on the detection surface of the detection housing, and several electrodes that are flush with or protrude from the detection surface. The electrodes are used to detect the presence of liquid on the patch and send the detection result to the microcontroller of the main unit. The microcontroller controls the optical sensor to detect whether the liquid is blood.

[0042] In this embodiment, some of the electrodes are positive electrodes and some are negative electrodes. When there is liquid on the patch, the positive and negative electrodes become conductive. The electrodes are arranged around the optical sensor, which is located in the center of the detection section. A light-transmitting plate is provided around the optical sensor, and this plate is flush with the detection surface of the detection housing. Figure 4 As shown, taking an example with four electrodes, two of which are positive electrodes (represented by 1) and two of which are negative electrodes (represented by 0), the positive and negative electrodes are alternately arranged around the optical sensor. This layout can accurately cover and sense liquid changes from four directions: above, below, left, and right.

[0043] The main unit also includes a light source driving circuit, an alarm, indicator lights, a communication module, a key detection circuit, and a power control circuit, all housed within the main unit casing. The microcontroller is also located within the main unit casing. The optical sensors and electrodes of the detection unit are connected to the microcontroller in the main unit; the light source driving circuit, alarm, indicator lights, and power control circuit are also electrically connected to the microcontroller. The microcontroller communicates with the main control device (such as a hemodialysis device) via the communication module, sending monitoring information to the main control device. In this embodiment, the communication module is preferably, but not limited to, Bluetooth.

[0044] like Figure 2 As shown, the power switch of the detection device is protruding or flush with the main unit casing, and the button detection circuit and the power control circuit share the power switch.

[0045] The circuit connections between the key detection circuit, power module, and power control circuit are as follows: Figure 5 As shown, power switch S1 is electrically connected to the voltage output terminal of the power module and the power interface of the microcontroller. Figure 5(Not shown in the diagram) Between the power switch S1 and the power interface of the microcontroller, a diode D1 is connected. The negative terminal of the diode D1 is connected in series with one end of a capacitor C10, and the other end of the capacitor C10 is grounded. The voltage output terminal of the power module is also connected to the source of the second MOSFET U2 and one end of the third resistor R3. The drain of the second MOSFET U2 is connected to the power interface of the microcontroller and one end of the capacitor C10. The gate of the second MOSFET U2 and the other end of the third resistor R3 are both connected to the collector of the first transistor Q1. The base of the first transistor Q1 is connected to a signal output terminal of the microcontroller, and the emitter of the first transistor Q1 is grounded. The power switch S1 is also electrically connected between the voltage output terminal of the power module and the base of the second transistor Q2. The emitter of the second transistor Q2 is grounded, and its collector is connected to a signal input terminal of the microcontroller.

[0046] When power switch S1 is pressed, the power control circuit is activated, powering the entire device and supplying power to the microcontroller. The microcontroller then begins operation, detecting the duration of the power switch S1 button press. When the press duration reaches the designed value, the microcontroller outputs a high-level signal to the base of the first transistor Q1, turning on Q1 and thus turning on the second MOSFET U2. Even if power switch S1 is released, the microcontroller can still maintain power supply by connecting to the power module via the second MOSFET U2. Power switch S1 can also be used as a function button. For example, pressing power switch S1 twice consecutively activates Q2, causing the microcontroller to receive a low-level signal from the collector of Q2 twice, triggering the Bluetooth broadcast function. Pressing power switch S1 three times consecutively outputs a low-level signal to the base of the first transistor Q1, turning off Q1 and disconnecting the power to the entire device.

[0047] During monitoring, the electrode detects the presence of liquid on the patch and sends the detection result to the microcontroller. The microcontroller controls the light source driving circuit to turn on and off. If liquid is present, the microcontroller controls the light source driving circuit to turn on, and the light source driving circuit controls the optical sensor to emit alternating flashing red and infrared light for blood detection. The determination of whether the liquid is blood is based on the following criteria: when blood is present, the values ​​of red and infrared light increase, and the difference between them also increases. The specific algorithm is as follows (red: red light; ir: infrared light):

[0048] When (red+ir)>30000 and (red-ir)>15000, the liquid is determined to be blood.

[0049] After power is turned on, the signal detected by the electrodes is sent to the microcontroller in real time. If the signal does not reach the humidity threshold, the microcontroller goes into sleep mode, the alarm is off, the light source drive circuit is off, the light sensor is off, and the indicator light flashes blue. When the electrode signal reaches the humidity detection threshold, the microcontroller is awakened, the light source drive circuit is activated, and the light sensor is turned on. If blood is detected, the alarm sounds, the indicator light flashes, and an alarm message is sent to the main control device via the communication module. If the signal reaches the humidity detection threshold, the microcontroller is awakened, the light source drive circuit is activated, and the light sensor is turned on. If blood is not detected, a warning is sent to the main control device via the communication module.

[0050] Alarm cancellation: When an alarm is triggered, the microcontroller continues to monitor the signal from the photosensitive sensor in real time. If the detected signal is blood, the current alarm state is maintained. If the detected signal is not blood, the signal from the electrode is monitored. If the electrode signal also does not reach the threshold, the alarm state is terminated, the alarm is turned off, and the indicator light flashes blue. If the detected signal is not blood, the signal from the electrode is monitored. If the electrode signal reaches the threshold, a warning is sent to the main control device via the communication module.

[0051] The communication module is preferably, but not limited to, a Bluetooth module. When the Bluetooth module is not connected for a long time, the microcontroller outputs a low level to the base of the first transistor Q1, and the first transistor Q1 is turned off, disconnecting the power supply to the entire device.

[0052] Example 2

[0053] This embodiment, based on the in vitro blood loss monitoring device proposed in Embodiment 1, provides an in vitro blood loss monitoring method, such as... Figure 6 and Figure 7 As shown, it includes the following steps:

[0054] Hang the main unit of the extracorporeal blood loss monitoring device on the side rod of the blood purification equipment or the side rod of the bed. Use medical tape to attach the detection part of the extracorporeal blood loss monitoring device to the special dressing near the puncture needle. After attaching it firmly, turn on the device and connect to the blood purification equipment via Bluetooth. After the connection is established, it enters a low power consumption state and automatically wakes up every 5 seconds to send the current status data to the blood purification equipment. You can view the connection status, battery level, blood loss status, and other data on the blood purification equipment.

[0055] To ensure comprehensive and accurate monitoring, the detection unit is placed in the center of the patch. Any minute changes in liquid in any direction can be captured and reported instantly and accurately, achieving a balance of sensitivity across monitoring directions and effectively avoiding false alarms or missed alarms caused by uneven local wetting.

[0056] The electrodes monitor the presence of liquid at the application site in real time.

[0057] If the signal detected by the electrode does not reach the humidity threshold, that is, the electrode does not detect a liquid signal, the intravenous needle has not fallen off, the dressing is dry and there is no blood, the external blood loss monitoring device operates at low power, and the optical sensor remains in sleep mode and does not emit light.

[0058] If the electrode detection signal reaches the humidity threshold, an electrode detection interruption is triggered, quickly waking the microcontroller within 5ms. Simultaneously, the optical sensor activates for blood identification. The optical sensor uses alternating red and infrared light flashing to collect the reflected light signal and determine if the liquid on the dressing is blood. If it is blood, an alarm sounds, an indicator light flashes, and an alarm message is sent to the main control device via the communication module. If it is not blood, the optical sensor continues to detect. If no blood is detected after a set time (e.g., 2 minutes), a warning signal is sent to the main control device via Bluetooth, prompting medical personnel to check the dressing, which may be wetted by saline, dialysis fluid, or other liquids. The warning is automatically deactivated once the electrode signal falls below the threshold.

[0059] While the optical sensor identifies blood, the electrodes continuously monitor the blood to prevent false alarms caused by interference signals. Electromagnetic interference and fluctuations are filtered out by a program to obtain a stable signal. When an alarm occurs, the microcontroller monitors the signal collected by the optical sensor in real time. If the liquid continuously detects blood, the current alarm status is maintained; if the liquid continuously detects non-blood, a warning signal is sent to prompt medical personnel to check the dressing; if the signal continuously detected by the electrodes does not reach the humidity threshold, the alarm is automatically deactivated.

[0060] When the optical sensor fails to detect blood and the signal detected by the electrode does not reach the temperature threshold, the optical sensor detection is turned off after 10 seconds, the blood recognition wake-up ends, and the external blood loss monitoring device continues to operate in low power mode.

[0061] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An external blood loss monitoring device, characterized in that, It includes a main unit and a detection unit. During monitoring, the detection unit comes into contact with the patch. The main unit includes a power control circuit and a button detection circuit. The power control circuit includes a first transistor and a second MOSFET. The button detection circuit includes a second transistor. The power switch is electrically connected between the voltage output terminal of the power module and the power interface of the microcontroller. The voltage output terminal of the power module is also connected to the source of the second MOSFET. The drain of the second MOSFET is connected to the power interface of the microcontroller. The gate of the second MOSFET is connected to the collector of the first transistor. The base of the first transistor is connected to a signal output terminal of the microcontroller. The emitter of the first transistor is grounded. The power switch is also electrically connected between the voltage output terminal of the power module and the base of the second transistor. The emitter of the second transistor is grounded, and its collector is connected to a signal input terminal of the microcontroller. The detection unit includes an optical sensor disposed on its detection surface and a plurality of electrodes that are flush with or protrude from the detection surface. The optical sensor and electrodes are respectively connected to the microcontroller of the host unit. The electrode is used to detect whether there is liquid on the patch and sends the detection result to the microcontroller. The microcontroller controls the optical sensor to detect whether the liquid is blood.

2. The extracorporeal blood loss monitoring device according to claim 1, characterized in that, The optical sensor is located in the middle of the detection unit, and there are four electrodes, which are respectively arranged around the optical sensor.

3. The extracorporeal blood loss monitoring device according to claim 1, characterized in that, The electrode consists of a number of positive and negative electrodes, which may be the same or different. When there is liquid on the patch, the positive and negative electrodes become conductive.

4. The extracorporeal blood loss monitoring device according to claim 1, characterized in that, The main unit also includes a light source driving circuit connected to a microcontroller. The microcontroller controls the light source driving circuit to turn on and off, and the light source driving circuit controls the optical sensor to emit alternating flashing red and infrared light for blood detection.

5. The extracorporeal blood loss monitoring device according to claim 1, characterized in that, The microcontroller is connected to the main control device and sends monitoring information to the main control device.

6. A method for monitoring blood loss in vitro, characterized in that, The extracorporeal blood loss monitoring device according to any one of claims 1-5 includes the following steps: Real-time monitoring to detect the presence of liquid at the application site; When liquid is detected at the application site, the optical sensor is triggered to detect whether the liquid is blood.

7. The method for monitoring in vitro blood loss according to claim 6, characterized in that, The electrodes perform real-time liquid detection. If the signal detected by the electrodes reaches the humidity threshold, it is determined that there is liquid at the application site. The microcontroller then activates the light source drive circuit and the light sensor, causing the optical sensor to emit alternating flashing red and infrared light to detect whether the liquid is blood.

8. The method for monitoring in vitro blood loss according to claim 6 or 7, characterized in that, When the signal detected by the electrode does not reach the humidity threshold, the alarm is turned off, the light source drive circuit is turned off, and the light sensor is turned off. When the electrode detection signal reaches the humidity threshold and the liquid detected is blood, the control alarm will sound, the indicator light will flash, and the microcontroller will communicate with the main control device to send an alarm message. When the liquid detected is not blood, the microcontroller will communicate with the main control device to send a warning message.

9. The method for monitoring in vitro blood loss according to claim 8, characterized in that, When an alarm occurs, the microcontroller monitors the signal collected by the optical sensor in real time. If the liquid continuously detects blood, the current alarm status is maintained; if the liquid continuously detects non-blood, a warning message is sent; if the signal continuously detected by the electrode does not reach the humidity threshold, the alarm is deactivated.

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