An intelligent temperature control system for an intraoperative warming blanket

Abstract

This invention discloses an intelligent temperature control system for intraoperative warming blankets, relating to the field of medical equipment technology. It automates intraoperative temperature management, reducing the need for medical staff to continuously monitor temperature and manually operate the warming blankets. This reduces the workload for medical staff, allowing them to focus on critical tasks such as surgical procedures and monitoring patient vital signs, thus lowering the risk of operational errors due to excessive workload and distraction. The system includes ambient temperature linkage alarm and adaptive adjustment functions. When the operating room ambient temperature falls below a preset threshold for a certain period, an alarm signal is automatically generated to remind medical staff to adjust the ambient temperature. Simultaneously, it proactively enters an active warming mode to compensate for heat loss caused by the low ambient temperature, reducing the frequency of intervention by medical staff and improving the convenience and efficiency of intraoperative temperature management.

Description

Technical Field

[0001] This invention relates to the field of medical equipment technology, specifically to an intelligent temperature control system for an intraoperative warming blanket. Background Technology

[0002] Perioperative hypothermia or unplanned hyperthermia is a highly prevalent complication in clinical anesthesia. Clinical data shows that the incidence of perioperative hypothermia in adults can reach 50%-70%, while in pediatric patients, due to their underdeveloped thermoregulatory centers, larger body surface area to weight ratio, and faster heat loss, the incidence is even higher, reaching 60%-85%, with neonates being particularly affected. This abnormal temperature not only affects the patient's physiological state during surgery but also leads to a series of serious adverse consequences. Hypothermia can cause delayed postoperative awakening, a 3-5 times increased risk of surgical site infection, coagulation disorders, and an increased incidence of cardiovascular events. It can even induce shivering, leading to a surge in oxygen consumption and increased organ burden. Unplanned hyperthermia, on the other hand, can cause febrile seizures, metabolic disorders, and electrolyte imbalances. In severe cases, it can damage the central nervous system, significantly affecting postoperative outcomes, prolonging hospital stays, and increasing medical costs.

[0003] In current technologies, forced-air warming blankets are commonly used in clinical practice as the core equipment for intraoperative temperature intervention. However, their control methods are relatively crude, with extremely low automation, relying entirely on manual operation and real-time monitoring by medical staff. Specifically, anesthesiologists need to frequently switch their attention to the patient's temperature monitor during surgery, manually turning the warming blanket on or off based on the instantaneous temperature data displayed on the monitor, and selecting an appropriate temperature from the device's preset, limited fixed settings. Existing devices commonly offer three settings: 32℃, 38℃, and 43℃, with a large range and a lack of fine-tuning capabilities.

[0004] There are many inevitable defects in this traditional control method, which seriously restricts the accuracy and safety of intraoperative body temperature management: First, it relies on the continuous observation and manual operation of medical staff. During the operation, anesthesiologists need to simultaneously monitor multiple core vital signs of the patient, such as heart rate, blood pressure, and blood oxygen saturation. The workload is extremely large, and it is very easy to cause hypothermia not to be detected and corrected in a timely manner due to distraction of attention and operation negligence. Especially in long and complex surgeries, the limitations of this manual monitoring are more prominent; Second, after the warming blanket is turned on, if the medical staff fails to turn off the device in a timely manner according to the patient's body temperature recovery, or due to improper gear selection, it is very easy to cause the patient's body temperature to be too high after surgery, or even cause high fever, bringing additional risks to the patient's recovery; Third, most of the existing warming blanket devices are mainly adapted to adults, lacking special size specifications for children and newborns. When children use adult models, it is easy to have problems such as poor fit of the air blanket and uneven heat distribution. Either local overheating causes the risk of scalding, or the insulation area is insufficient, resulting in poor insulation effect. Moreover, the skin of newborns is delicate, and the temperature output accuracy of the existing devices cannot meet their fragile temperature regulation needs; Fourth, the existing devices have a single function, only having the function of heating and insulation, lacking the ability of automatic cooling and heat dissipation adjustment. When the patient has an unexpected high body temperature, the medical staff can only manually turn off the warming blanket, unable to achieve precise cooling intervention through the device, and can only passively wait for the patient's body temperature to naturally drop, delaying the cooling opportunity; Fifth, the existing devices do not realize the linkage adjustment with the operating room environment temperature. The fluctuation of the operating room environment temperature will directly affect the patient's body temperature change, but the existing warming blankets always operate with fixed parameters and cannot adaptively adjust the temperature and wind speed output according to the change of the environment temperature, resulting in poor stability of body temperature control and difficulty in maintaining the patient's body temperature fluctuating smoothly within the target range.

[0005] In addition, the existing intraoperative body temperature management is mostly a passive intervention mode, that is, only after the patient's body temperature shows obvious abnormalities, the medical staff starts the warming blanket for intervention, and it is impossible to make predictive adjustments according to the trend of the patient's body temperature change, making it difficult to achieve full-process and dynamic precise body temperature control. In summary, the problems of extensive control, single-function design, and insufficient adaptability of the current clinical intraoperative body temperature management equipment can no longer meet the clinical refined and intelligent body temperature management needs, especially cannot adapt to the diagnosis and treatment needs of special patient groups such as pediatrics and newborns. There is an urgent need for a solution that can automatically, precisely, and intelligently achieve full-process prediction and closed-loop control of intraoperative body temperature, fill the existing technical gaps, improve the safety and convenience of intraoperative body temperature management, and improve the postoperative outcome of patients. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention provides an intelligent temperature control system for intraoperative warming blankets. This system can automatically and intelligently switch the working mode of the warming blanket and finely adjust the output temperature and airflow to achieve precise and stable closed-loop body temperature control, providing excellent intraoperative body temperature protection for patients, especially pediatric patients.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: An intelligent temperature control system for intraoperative warming blankets includes: Acquire patient body temperature data and operating room ambient temperature data; Based on the patient's body temperature data and its changing trend, patient type parameters, and ambient temperature data, the working mode and parameters of the heating blanket main unit are automatically adjusted to achieve automatic closed-loop control and protection of the patient's body temperature.

[0008] In some embodiments of this application, the automatic adjustment of the working mode and parameters of the heating blanket host based on the patient's body temperature data and its changing trend, patient type parameters, and ambient temperature data includes: With the heating blanket main unit turned on, the corresponding target body temperature range is determined according to the patient type parameters; Based on the comparison between the current patient's body temperature data and the target body temperature range, as well as the trend of the patient's body temperature change, the initial working mode is determined. During the operation of the heating blanket main unit, based on real-time patient body temperature data, its changing trend and ambient temperature data, it determines whether the predetermined mode switching or parameter adjustment conditions are met, and automatically switches the working mode or adjusts the output temperature and wind speed accordingly.

[0009] In some embodiments of this application, when the heating blanket host is powered on, determining the corresponding target body temperature range based on the patient type parameter, and determining the initial working mode based on the comparison between the current patient body temperature data and the target body temperature range, as well as the patient body temperature change trend, includes: Determine whether the first condition is met, wherein the first condition is that the patient's body temperature is lower than a first temperature threshold and the duration is greater than a first predetermined time, and the first temperature threshold is the lower limit of the target body temperature range or a temperature close to the lower limit. If the first condition is met, the heating blanket unit is turned on in the first heating mode; If the first condition is not met, determine whether the second condition is met, wherein the second condition is that the patient's body temperature is higher than a second temperature threshold and the duration is greater than a second predetermined time, and the second temperature threshold is the upper limit of the target body temperature range or a temperature close to the upper limit. If the second condition is met, the heating blanket unit will be turned on in ventilation mode; If the first and second conditions are not met, the heating blanket main unit will be turned on in either maintenance mode or low-power heating mode.

[0010] In some embodiments of this application, the step of determining whether predetermined mode switching or parameter adjustment conditions are met based on real-time patient body temperature data, its changing trend, and ambient temperature data during the operation of the heating blanket main unit, and automatically switching the working mode or adjusting the output temperature and fan speed accordingly, includes: When the heating blanket host is running in the first heating mode, it is determined whether the third condition is met. The third condition is that the patient's body temperature rises to a level higher than the third temperature threshold and the duration is greater than the third predetermined time. The third temperature threshold is between the lower limit and the upper limit of the target body temperature range. When the third condition is met, the heating blanket main unit switches to the second heating mode, wherein the output temperature of the second heating mode is lower than that of the first heating mode, and / or the wind speed is lower than that of the first heating mode; If the third condition is met, the heating blanket main unit switches to the maintenance mode.

[0011] In some embodiments of this application, the step of determining whether predetermined mode switching or parameter adjustment conditions are met based on real-time patient body temperature data, its changing trend, and ambient temperature data during the operation of the heating blanket main unit, and automatically switching the working mode or adjusting the output temperature and fan speed accordingly, further includes: When the heating blanket host is running in the first heating mode or the second heating mode, it is determined whether the fourth condition is met, wherein the fourth condition is that the patient's body temperature rises to a level higher than the second temperature threshold and the duration is greater than the fourth predetermined time. If the fourth condition is met, the heating blanket unit switches to the ventilation mode.

[0012] In some embodiments of this application, the step of determining whether predetermined mode switching or parameter adjustment conditions are met based on real-time patient body temperature data, its changing trend, and ambient temperature data during the operation of the heating blanket main unit, and automatically switching the working mode or adjusting the output temperature and fan speed accordingly, includes: When the heating blanket host is in the ventilation mode, it is determined whether the fifth condition is met, wherein the fifth condition is that the patient's body temperature drops below the fourth temperature threshold and the duration is greater than the fifth predetermined time, and the fourth temperature threshold is between the lower limit and the upper limit of the target body temperature range. If the fifth condition is met, the heating blanket main unit switches to the second heating mode or the maintenance mode.

[0013] In some embodiments of this application, the system further includes: Monitor the ambient temperature data of the operating room; When the ambient temperature data of the operating room is lower than the preset ambient temperature alarm threshold and the duration is greater than a sixth predetermined time, an ambient low temperature alarm message is generated.

[0014] According to another aspect of this application, a device based on an intelligent temperature control system for intraoperative warming blankets is provided, comprising: The data acquisition module is used to acquire patient body temperature data and operating room ambient temperature data; The intelligent control module is used to automatically adjust the working mode and parameters of the heating blanket host according to the patient's body temperature data and its changing trend, patient type parameters and ambient temperature data, so as to realize automatic closed-loop control and protection of the patient's body temperature.

[0015] Memory, used to store instructions; A processor is configured to execute the instructions, causing the intelligent intraoperative body temperature protection device to perform operations implementing the intelligent intraoperative body temperature protection method as described in any of the above embodiments.

[0016] The heating blanket main unit is used to automatically switch working modes and adjust output parameters according to the control instructions of the intelligent intraoperative body temperature protection device, so as to automatically control and protect the patient's body temperature in a closed loop. The heating blanket unit includes replaceable air blankets with different sizes to fit adults, children and newborns respectively.

[0017] The heating blanket host is used to automatically switch working modes and adjust output temperature and wind speed according to the control instructions of the intelligent intraoperative body temperature protection device as described in any of the above embodiments, so as to automatically control and protect the patient's body temperature in a closed loop.

[0018] The beneficial effects of this invention are: An intelligent temperature control system based on an intraoperative warming blanket automates intraoperative temperature management, reducing the need for medical staff to continuously monitor temperature and manually operate the warming blanket. This reduces their workload, allowing them to focus on critical tasks such as surgical procedures and monitoring patient vital signs, thus minimizing the risk of errors due to excessive workload and distraction. The system includes ambient temperature-linked alarm and adaptive adjustment functions. When the operating room ambient temperature falls below a preset threshold for a certain period, an alarm signal is automatically generated to remind medical staff to adjust the ambient temperature. Simultaneously, the system proactively enters an active warming mode to compensate for heat loss caused by the low ambient temperature, reducing the frequency of medical staff intervention and improving the convenience and efficiency of intraoperative temperature management.

[0019] For existing heating blankets that only have heating functions, this system adds a ventilation mode to achieve temperature intervention throughout the entire process of heating, heat preservation, cooling, and heat dissipation. It can correct hypothermia in a timely manner and automatically switch to ventilation when the patient has unplanned hyperthermia, delivering room temperature airflow to achieve active cooling. This avoids the delay in cooling caused by passively waiting for the body temperature to drop naturally, and adapts to the management needs of various intraoperative abnormal body temperature scenarios.

[0020] This invention differs from existing passive intervention-based temperature management models. By analyzing the patient's temperature change trend, it can predict the risk of abnormal temperature in advance, proactively switch working modes and adjust equipment parameters, avoiding frequent mode switching caused by short-term temperature fluctuations, and ensuring that the patient's temperature remains stable within the target range, thereby further improving the stability and reliability of temperature management.

[0021] The technical solutions of the present disclosure will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative effort are within the scope of protection of the present disclosure.

[0022] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0023] The technical solutions of the present disclosure will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative effort are within the scope of protection of the present disclosure.

[0024] This disclosure provides an intelligent temperature control system for intraoperative warming blankets, including steps S11 and S12.

[0025] Step S11: Obtain patient body temperature data and operating room ambient temperature data.

[0026] Patient body temperature data is collected via temperature probes placed on or inside the patient's body. Operating room ambient temperature data is collected via temperature sensors installed within the operating room. Patient type parameters are entered into the system before surgery via a human-machine interface.

[0027] Step S12: Based on the patient's body temperature data and its changing trend, patient type parameters, and ambient temperature data, the working mode and parameters of the heating blanket host are automatically adjusted to achieve automatic closed-loop control and protection of the patient's body temperature.

[0028] The system retrieves the preset target body temperature range [T] based on the patient type. low T high The control logic is based on the current body temperature T. p Deviation from the target interval, rate of change of body temperature ΔT rate and ambient temperature T e Make comprehensive decisions.

[0029] In a specific control logic, the system includes the following steps: S201, the system is powered on, patient information is entered, and the target body temperature range is determined.

[0030] S202, Determine the current patient's body temperature T p Is it lower than T? low And the duration exceeds t1. If yes, execute S203; otherwise, execute S206.

[0031] S203, the heating blanket main unit is turned on in the first heating mode, set with a higher output temperature and a medium fan speed to quickly correct low body temperature.

[0032] S204, under the first heating mode, is continuously monitored. T is determined. p Has it risen above the midpoint T of the interval? mid And the duration exceeds t2. If yes, execute S205; otherwise, return to S204.

[0033] S205, switch to the second heating mode, reduce the output temperature to close to body temperature and use low fan speed to maintain stable body temperature and prevent overheating.

[0034] S206, Determine T p Is it higher than T? high And the duration exceeds t3. If yes, execute S207; otherwise, execute S210.

[0035] The S207 heating blanket unit is turned on in ventilation mode, delivering room temperature airflow to help dissipate heat.

[0036] S208, under ventilation mode, continuous monitoring. Determine T. p Has it fallen below T? mid And the duration exceeds t4. If yes, execute S209; otherwise, return to S208.

[0037] S209, switch to the second heating mode or maintenance mode to prevent excessive drop in body temperature.

[0038] S210, at this point the body temperature is within a safe range. The system can maintain the mode on, delivering a weak airflow to keep the covered area ventilated, or standby for observation.

[0039] This disclosure provides an intelligent temperature control system based on an intraoperative warming blanket. In S12, the target body temperature range is specifically [36.5℃, 37.5℃] for newborns, [36.0℃, 38.0℃] for children, and [36.0℃, 37.5℃] for ordinary adults.

[0040] This disclosure provides an intelligent temperature control system based on an intraoperative warming blanket, wherein the determination in step S202 further includes the current patient body temperature T. p Is it lower than T? low +0.3℃; The range of t1 is 1-5 min, and the preferred value of t1 is 2 min.

[0041] This disclosure provides an intelligent temperature control system based on an intraoperative warming blanket, wherein the higher output temperature in S203 is 38-40℃.

[0042] This disclosure provides an intelligent temperature control system based on an intraoperative warming blanket, wherein t2 in S204 ranges from 1 to 5 minutes, and t2 is preferably 3 minutes.

[0043] This disclosure provides an intelligent temperature control system based on an intraoperative warming blanket, wherein the determination in step S202 further includes the current patient body temperature T. p Is it higher than T? high -0.3℃.

[0044] This disclosure provides an intelligent temperature control system based on an intraoperative warming blanket, wherein t2 in S208 ranges from 2 to 8 minutes, and t2 is preferably 5 minutes.

[0045] Based on the intelligent intraoperative body temperature protection method provided in the above embodiments of this application, an intelligent temperature control system for intraoperative warming blankets can be provided for perioperative patients, especially pediatric patients.

[0046] The above embodiments of this application are based on an intelligent heating blanket host, combined with integrated body temperature monitoring, ambient temperature monitoring and intelligent control logic, to monitor and dynamically regulate the patient's core body temperature in real time during surgery. Through automatic switching and adjustment of working modes and parameters, it adapts to the body temperature effects caused by changes in patient metabolism, surgical trauma stress and fluctuations in operating room ambient temperature, and can meet the patient's individualized body temperature maintenance needs, providing the patient with a stable intraoperative environment.

[0047] The embodiments described above in this application achieve more precise and forward-looking body temperature regulation by incorporating body temperature change trends and patient type parameters for comprehensive decision-making, thus solving the problem of large fluctuations in patient body temperature caused by response delays or coarse control in related technologies.

[0048] The embodiments described above can automatically switch between multiple operating modes, including heating, maintenance, and ventilation, and achieve stepless or fine multi-level adjustment of output temperature and airflow, thus achieving precise temperature control and providing patients with safe and comfortable intraoperative temperature protection. The above embodiments of this application achieve automatic operation, reducing the workload and risk of negligence for anesthesiologists who rely entirely on manual intervention, thereby solving the problem of untimely or inaccurate temperature control caused by the complete dependence on manual observation and operation in related technologies.

[0049] The embodiments described above in this application integrate patient body temperature monitoring functions and link them with ambient temperature monitoring to construct a complete body temperature sensing network, thereby solving the problem of lacking proactive intervention in environmental factors.

[0050] The above-described embodiments of this application, through intelligent, automated, and personalized body temperature management, can effectively prevent perioperative hypothermia and unplanned hyperthermia, improve the quality of postoperative recovery, reduce the risk of complications, and promote postoperative rehabilitation.

[0051] Meanwhile, the system continuously monitors the ambient temperature T. e If T e If the temperature is below the preset standard (e.g., 22℃) for a certain period of time, an audible and visual alarm will be triggered to prompt medical staff to adjust the air conditioning. The system itself can also enter a more proactive heat preservation mode in advance as compensation.

[0052] The specific values ​​of the aforementioned predetermined times t1-t4 and temperature thresholds can be set and adjusted based on clinical experience and different patient groups, in order to avoid frequent mode switching caused by short-term fluctuations in body temperature and ensure stable control.

[0053] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," 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, 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.

[0054] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An intelligent temperature control system for an intraoperative warming blanket, characterized in that, include: Acquire patient body temperature data and operating room ambient temperature data; Based on the patient's body temperature data and its changing trend, patient type parameters, and ambient temperature data, the working mode and parameters of the heating blanket host are automatically adjusted to achieve automatic closed-loop control and protection of the patient's body temperature. The automatic adjustment of the working mode and parameters of the heating blanket host based on the patient's body temperature data and its changing trend, patient type parameters, and ambient temperature data includes: With the heating blanket main unit turned on, the corresponding target body temperature range is determined according to the patient type parameters; Based on the comparison between the current patient's body temperature data and the target body temperature range, as well as the trend of the patient's body temperature change, the initial working mode is determined. During the operation of the heating blanket main unit, based on real-time patient body temperature data, its changing trend and ambient temperature data, it determines whether the predetermined mode switching or parameter adjustment conditions are met, and automatically switches the working mode or adjusts the output temperature and wind speed accordingly.

2. The intelligent temperature control system for intraoperative warming blankets as described in claim 1, characterized in that, When the heating blanket main unit is powered on, the process of determining the corresponding target body temperature range based on the patient type parameters, and determining the initial working mode based on the comparison between the current patient body temperature data and the target body temperature range, as well as the patient's body temperature change trend, includes: Determine whether the first condition is met, wherein the first condition is that the patient's body temperature is lower than a first temperature threshold and the duration is greater than a first predetermined time, and the first temperature threshold is the lower limit of the target body temperature range or a temperature close to the lower limit. If the first condition is met, the heating blanket unit is turned on in the first heating mode; If the first condition is not met, determine whether the second condition is met, wherein the second condition is that the patient's body temperature is higher than a second temperature threshold and the duration is greater than a second predetermined time, and the second temperature threshold is the upper limit of the target body temperature range or a temperature close to the upper limit. If the second condition is met, the heating blanket main unit is turned on in ventilation mode or first cooling mode. If the first and second conditions are not met, the heating blanket main unit will be turned on in either maintenance mode or low-power heating mode.

3. The intelligent temperature control system for intraoperative warming blankets as described in claim 2, characterized in that, During the operation of the heating blanket main unit, based on real-time patient body temperature data, its changing trend, and ambient temperature data, it determines whether predetermined mode switching or parameter adjustment conditions are met, and automatically switches the working mode or adjusts the output temperature and fan speed accordingly. When the heating blanket host is running in the first heating mode, it is determined whether the third condition is met. The third condition is that the patient's body temperature rises to a level higher than the third temperature threshold and the duration is greater than the third predetermined time. The third temperature threshold is between the lower limit and the upper limit of the target body temperature range. When the third condition is met, the heating blanket main unit switches to the second heating mode, wherein the output temperature of the second heating mode is lower than that of the first heating mode, and / or the wind speed is lower than that of the first heating mode; If the third condition is met, the heating blanket main unit switches to the maintenance mode.

4. The intelligent temperature control system for intraoperative warming blankets as described in claim 3, characterized in that, During the operation of the heating blanket main unit, based on real-time patient body temperature data, its changing trend, and ambient temperature data, it is determined whether predetermined mode switching or parameter adjustment conditions are met, and accordingly, the working mode is automatically switched or the output temperature and fan speed are adjusted. When the heating blanket host is running in the first heating mode or the second heating mode, it is determined whether the fourth condition is met, wherein the fourth condition is that the patient's body temperature rises to a level higher than the second temperature threshold and the duration is greater than the fourth predetermined time. If the fourth condition is met, the heating blanket main unit switches to the ventilation mode or the first cooling mode.

5. The intelligent temperature control system for intraoperative warming blankets as described in claim 4, characterized in that, During the operation of the heating blanket main unit, based on real-time patient body temperature data, its changing trend, and ambient temperature data, it determines whether predetermined mode switching or parameter adjustment conditions are met, and automatically switches the working mode or adjusts the output temperature and fan speed accordingly. When the heating blanket host is running in the ventilation mode or the first cooling mode, it is determined whether the fifth condition is met. The fifth condition is that the patient's body temperature drops below the fourth temperature threshold and the duration is greater than the fifth predetermined time. The fourth temperature threshold is between the lower limit and the upper limit of the target body temperature range. If the fifth condition is met, the heating blanket main unit switches to the second heating mode or the maintenance mode.

6. The intelligent temperature control system for intraoperative warming blankets as described in claim 5, characterized in that, The system also includes: Monitor the ambient temperature data of the operating room; When the ambient temperature data of the operating room is lower than the preset ambient temperature alarm threshold and the duration is greater than a sixth predetermined time, an ambient low temperature alarm message is generated.