Application of RTLS technology based on wireless local area network in a hospital in Hangzhou
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1 Program overview
Nowadays, the domestic medical industry is facing increasing financial pressure, urgent need to improve the level of medical services, patient safety monitoring, etc. The problem is the lack of a location for patients, medical staff, medical equipment and other movable assets. And a visual solution for real-time monitoring of status. Such as: medical equipment that cannot be maintained in time due to misplaced placement; patients who go to the wrong ward; cold rooms with temperature-sensitive items open, all of which will have a great negative impact on the hospital’s medical work.
This article addresses the above problems and introduces a medical tracking solution based on standard wireless local area network (Wi-Fi). No need to rebuild other networks or facilities, it can be quickly deployed and installed on the basis of the original wireless local area network, build a medical visualization platform, and provide medical institutions with complete asset, patient and staff tracking solutions to help reduce operating costs and improve operations Efficiency and level of medical service. This solution is suitable for domestic hospitals.
2 Introduction of wireless local area network real-time positioning system (Wi-Fi RTLS)
2.1 Main components
The wireless real-time positioning system consists of a wireless network access point (AP), Wi-Fi positioning electronic tags or Wi-Fi mode wireless terminal devices (such as mobile phones, PDAs, laptops), and a positioning server.
2.2 Working principle
The electronic tag or wireless device periodically sends a signal to the AP, or the AP actively searches for the electronic tag or wireless device periodically. After the AP obtains the signal, it is transmitted to the back-end positioning server. The positioning server uses the precise positioning algorithm to display it on the electronic map in the web interface in real time. Display the specific location of the electronic tag or wireless device. At the same time, the tag can implement two-way communication with the server through the AP. The tag can send information to the positioning server, and the positioning server can also send instructions to the tag to classify and manage the tags.
2.3 System advantages
(1) Wi-Fi network based on global common standards, no need for readers, no need to re-build other networks or facilities, installation and implementation are flexible, convenient and quick, and cost reduction;
(2) It integrates multiple functions such as real-time positioning, historical running track playback and analysis, label instant alarm, label disappearance alarm, automatic alarm for entry and exit prohibited areas, intelligent sensor control and alarm;
(3) Support various types of WiFi electronic tags, handheld terminals, WiFi phones, and mobile computers to meet the special needs of various industries;
(4) Long-distance recognition, more than 300 meters outdoors, 100 meters indoors
(5) Accurate positioning indoors and outdoors up to 3 meters;
(6) A comprehensive system integrating wireless Internet access, real-time positioning monitoring, linkage with cameras, intelligent sensing, access control, attendance, electronic consumption, video, and voice.
Under the leadership of a number of PhDs in the United States, the Sino-U.S. technical team of Youpin Technology has combined technologies such as radio frequency signal optimization, multiple positioning algorithm integration, electronic map data analysis and generation, and software platform architecture optimization. It has been independent for more than ten years. Developed WiFi real-time positioning system. The core technology of the positioning engine of the system has obtained 2 national invention patents and 11 software copyrights, and has been continuously improved through hundreds of actual cases. It has the characteristics of high accuracy, strong interference, good stability, and strong scalability, reaching the international level. Leading level.
2.4 The real-time positioning system of Youpin Technology has the following advantages:
High positioning accuracy: It can achieve positioning accuracy of 3-5 meters, and key areas of 1-2 meters, which fully meets the needs of nursing home personnel positioning;
Multiple positioning algorithms: support a variety of positioning algorithms, including triangulation, wireless fingerprint positioning, round-trip time positioning, self-organizing network positioning, combined with historical trajectory analysis and scene structure analysis, to improve positioning accuracy and stability;
Customized calculation: According to different environmental locations, the running track can be set to increase the positioning accuracy and stability, and there will be no cases of passing through walls or jumping floors;
Strong adaptability: It can automatically judge the WiFi chip manufacturers of different terminals and the interference of the human body, and automatically adjust the positioning parameters to increase the positioning accuracy and stability;
The number of positioning can be expanded: a single positioning engine can locate 2000 terminal devices at the same time within 1 second, adopting a distributed architecture, can support multiple positioning engines at the same time, and manage millions of terminal devices;
Support any WiFi terminal device positioning: the positioning engine supports both AP active scanning mode and terminal scanning mode. Although Apple’s iOS7 prohibits APP from obtaining the WiFi MAC address, our unique solution can realize the positioning of iOS devices, and it can also be based on iOS devices. MAC address push information function;
Support WiFi tags: Support one-way transmission of ultra-low power WiFi location tags, wristbands, WiFi sensors, to achieve tracking and status monitoring of personnel and objects;
Support cloud computing: The location AP of any place can be transmitted to the cloud server via the Internet;
There are many AP manufacturers in cooperation: The equipment of mainstream AP manufacturers at home and abroad supports our positioning engine;
Integrated one-card: Integrate personnel positioning, consumption, and access control systems to realize intelligent one-card services;
Rich actual operation: Youpin Technology has hundreds of successful WiFi positioning cases at home and abroad, including nursing homes, exhibition halls, office buildings, factories, ports, prisons, coal mines and other industries in various complex environments;
3 Application of real-time positioning system (Wi-Fi RTLS) in the medical industry
3.1 Mother and child management
Newborn babies have little difference in appearance. They have no sense of self-protection and need careful care from medical staff. The real-time positioning system can solve the problems of mother-infant pairing and infant anti-theft, and realize the safety of mother-infant.At present, RFID radio frequency technology is basically adopted for mother and child management solutions. Passive wristband tags are worn for babies and mothers, and medical staff hold hands.RFIDThe reader reads the information of the mother and the baby respectively, and compares whether they are paired. Install RFID readers in the baby room, only those with passive tags can enter the baby room, and regularly read the visit records of the reader. Real-time monitoring is not possible, and it is impossible to avoid theft by people with passive tags Or drop the baby.
(1) Mother and baby pairing
Babies and mothers wear wristband tags and card tags respectively, and enter baby and current tag information on the back-end positioning server, such as personal information, medical history information, feeding times, hygiene status, medication records, and so on. The medical staff can read the tag information in real time by holding the PDA. Only when the mother’s information is paired with the baby’s information can the medical staff get out of the baby room. Otherwise, the pairing information will not match, and the back-end software will lock the access control in real time and the medical staff cannot get out.
(2) Secondary matching ensures a foolproof mother-to-child pairing
After the medical staff took the baby out of the nursery and sent it to the mother’s ward, the mother’s label and the baby’s label were close together. If the two labels do not match, an alarm will appear on the back-end server. In this way, it is avoided that after the medical staff walked out of the baby room, due to negligence or other human reasons, the wrong pairing error occurred due to the wrong mother’s ward.
(3) Baby anti-theft
Disassembly warning: The wristband label worn by the baby has the functions of anti-disassembly, waterproof, high temperature and intermittent prevention. The label will not leave the baby from the birth to the discharge from the hospital. If the wristband tag is detached from the system in any way, it will alert you.
Location alarm: When the baby is carried away from the nursery or mother’s room, the back-end server will give an alarm, provide the baby’s location information in real time, and replay the baby’s historical running track.
Real-time positioning and video monitoring linkage: The real-time positioning system can be linked with camera monitoring. When the position of the baby with the tag moves, the tag will stimulate the camera to take pictures or video, upload the back-end positioning server, and the manager can view the baby’s safety status in real time . Thus, the baby is effectively prevented from being stolen.
3.2 Special patient management
(1) Real-time location information query: wear for patientselectronic label, The real-time location information of the patient in the hospital can be viewed on the back-end positioning server to ensure that the patient is in a safe environment.
(2) Emergency alert: When a patient encounters an emergency, such as a disabled patient falling down in the bathroom, a child cannot find his room, a sudden illness patient has a sudden onset, etc., the patient can press the label alert button he is wearing. , The back-end positioning server immediately displays an alarm prompt, and the management personnel can immediately respond and arrange rescue.
(3) Hospital special management: There are many areas where patients are prohibited from entering the hospital, which requires strict monitoring and management. If a patient with a tag breaks into this area, the alarm function of the back-end positioning server will be triggered to remind the management staff to deal with it immediately.
(4) Security scope definition: In order to better maintain the safety of special patients, the hospital can arrange special patients in a safe area according to the actual situation. If the patient walks out of the safe area, the tag carried by the patient will send an alarm message to the back-end positioning server. Managers can arrange for medical staff to deal with it in real time.
(5) Alarm for leaving the hospital: If the patient arbitrarily enters the hospital, that is, the tag disappears within the wireless network coverage area, the back-end server will display a disappearing warning prompt.
(6) Intensive care unit management: The tag has a built-in sensor module, which can collect parameters such as temperature and air humidity in the intensive care unit in real time; the tag is linked with access control and camera to monitor the situation of people entering the intensive care unit in real time; set access permissions to avoid Interference from outsiders.
(7) Isolation and management of patients with infectious diseases: Wear tags for patients with infectious diseases. If patients with infectious diseases walk out of the next ward without authorization, the tags will trigger the access control system. Other personnel.
3.3 Medical equipment management
(1) Real-time location query of emergency equipment: first-aid equipment in hospitals, such as ventilators, infusion pumps, emergency surgical equipment, oxygen delivery devices, etc., are equipped with electronic tags, and enter the name of the equipment on the server when necessary to query the storage of the equipment in real time The location will not delay the rescue of the patient because of the search for the equipment.
(2) For people with mobility impairments and need to use a wheelchair, tags can be attached to the wheelchair. When the patient in the wheelchair needs help, the alarm button can be pressed. The back-end system receives the alarm information in real time, and personnel can be arranged to help. At the same time, the real-time position of the wheelchair can be inquired in real time, which improves the effective utilization rate of the wheelchair.
3.4 Supervision of Special Drugs
(1) Drug management with high requirements for the external environment: tags with built-in sensors can collect parameter information such as temperature and humidity in the environment where the drug is located in real time. According to the environmental requirements of the drug, set the limit values of temperature and humidity parameters on the back-end server , When the value passed by the tag exceeds the limit value, an alarm message will be triggered.
(2) Management of the effective use time of medicines: various medicines have priority use time limits. The labels of medicines are classified and divided on the back-end server, and relevant time information of the medicine labels is entered, time reminders are set, and medicines expire Or when the expiration date is approaching, an alarm will be triggered.
3.5 Optimize hospital workflow
(1) Find a doctor instantly: The doctor wears an electronic tag, and the administrator can see the doctor’s real-time location information on the back-end positioning server interface. When there is an emergency to find the doctor, the doctor can send instruction information to the label through the positioning server. After receiving the reminder, I know that I have an emergency, and I can go back to the clinic immediately.
(2) Ensure the safety of medical staff: If a medical staff encounters an emergency situation, such as being attacked by a patient, or unable to return to the clinic due to an emergency, the doctor can press the alarm button on the label to inform the back-end management center of his real-time situation.
(3) Keep abreast of various patient information, such as medical history, medication status, and daily nutritional meals for special patients (such as diabetic patients) through wireless means.
4 Description of the main functions of the system
4.1 Positioning monitoring
4.1.1 Real-time monitoring
1) The icon displayed on the map corresponds to the person or thing bound to the label;
2) Monitor the label in real time and display the current position of the label on the map;
3) The label flashes to indicate that there is an alarm;
4) Label grouping and display with different icons;
5) The smooth movement of the icon can be seen in real time during the positioning process;
6) Search personnel’s name and status:
7) The specified label can be tracked, and the map automatically switches with the movement of the label;
8) Move the mouse to the icon to see the information and status of the icon;
9) After clicking the icon, the detailed information of the person can be displayed;
10) You can manually switch the map to view the activity of all tags on the specified map;
11) The map can be zoomed in and out, adjusted to a suitable size;
12) The map will automatically switch floors when tracking a single label.
4.1.2 Real-time alarm
1) Trigger the alarm, pop up the page, sound the alarm, and display the corresponding video recording;
2) After clicking on the process, the page can be closed, otherwise it will keep reminding;
3) Real-time alarm list.
4.1.3 Track playback
1) The trajectory can be customized and modified;
2) The movement track is displayed smoothly;
3) You can lock a label, play according to time period, display movement (with or without track), and switch the map;
4) Can be played in full screen;
4.2 Label management
Tag management is divided into medical staff and patient management.
(1) Label issuance, the label ID is automatically obtained through the card issuing machine;
(2) Bind the tag with the person: Bind the specified person’s information with the tag worn by it, and the tag displayed in the system represents the person wearing the tag;
(3) The corresponding personnel for label replacement;
(4) Personnel information setting: Personnel information can be set and managed in the system;
(5) Label grouping and classification: Labels can be grouped and classified according to actual conditions.
4.3 Alarm management
(1) Button alarm setting: The label has a button alarm function. When an emergency occurs, the button can be pressed to send out an alarm message;
(2) Wristband cutting alarm setting;
(3) Out-of-bounds alarm: some areas are restricted areas, an alarm message will be issued if tags enter without permission, or some patients cannot leave a certain area, once they leave, an alarm message will be issued;
(4) Inconsistent with the management information system, alarm: The patient has already set the room number in the system. Once the patient enters the wrong room, an alarm will be sent out in time.
(5) Disappearance alarm setting-There are many factors for label disappearance (such as dead battery, label crossing the signal coverage area, etc.), you can set the disappearance alarm condition and alarm level of the specified label. If the label disappears, it will trigger the corresponding The alarm;
(6) Low battery alarm setting-once the label power is below a certain limit, an alarm message will be issued;
(7) Failure to follow the prescribed route to alarm-specify the walking trajectory of a certain tag for a certain period of time, once the label is found to deviate from the specified walking trajectory for a certain period of time, an alarm message will be issued;
(8) No accompanying personnel alarm-bind the patient tag and the medical staff label, one-to-one or many-to-many binding, when the walking trajectory of the patient label is inconsistent with the walking trajectory of the medical staff label and reaches a certain period of time, Issue an alarm message.
4.4 System Management
(1) User management: Various user permissions can be set. After users log in to the system, they can perform corresponding operations and browse content that meets the permissions according to their own permissions.
(2) If the map has been divided into areas, you can set the conditions for each label to enter and exit each area.
(3) AP locator management: monitor the working status of the AP locator and query historical records.
4.5 Statistical Report
(1) Label warning record: View all warning records of all labels or specified labels;
(2) View the label report: View the important alarms of the label, the statistics of the number of times of entering and exiting the area and the stay time;
(3) Operation history: view the user’s operation history;
5 Positioning algorithm and network design
5.1 Introduction to positioning algorithm
The Wi-Fi positioning system is based on the standard IEEE 802.11 wireless local area network (WLAN). The positioning algorithm is based on the received Wi-Fi signal strength (RSSI). Where the wireless local area network is covered, the positioning tag periodically sends out a signal, and the wireless local area network access point (AP) receives the signal and transmits the signal to the positioning server. The positioning server judges the location of the tag from the AP based on the strength of the signal. The location of the tag can be calculated by the distance between the tag and at least 3 APs, and the specific location is displayed on the electronic map. This is the traditional triangulation principle.
The Wi-Fi wireless signal arrives at the receiver after being reflected instead of a straight path, which brings a large error to the positioning calculation. This phenomenon is called multipath. Because obstacles in the indoor space will cause multipath interference, resulting in large signal changes, the traditional triangulation method is not suitable for indoor environments. We use a positioning method based on RF fingerprint recognition (FINGERPRINTING). Set multiple sampling points in the positioning area, and place the positioning terminal at one sampling point. Our scenario planning tool can record the signal characteristics emitted by the positioning terminal, and establish signal patterns based on these characteristics and signals at different locations to indicate the location of the positioning terminal. After the database is established using the signal pattern and the corresponding position information, the positioning system can calculate the position based on the signal characteristics collected in real time. The human body interferes with tags. Our positioning system adopts methods such as historical movement trajectories, adding AP locators, and correcting signal mutations to minimize the positioning error caused by interference in the algorithm.
5.2 Positioning accuracy
The positioning accuracy is related to the positioning target, the environment and the laying density of the locator. The fixed object can reach 3 meters or even better. When positioning people, due to human body interference, the accuracy is within a radius of 5-10 meters. The positioning accuracy is related to the distribution density of the locator, the environment, and the interference of the positioning object, so the accuracy of the wireless positioning is not an absolute number. Generally speaking, the accuracy can reach 3 meters to 5 meters, sometimes 10 meters or even worse. We also have applications that can achieve 1.5 meters. The higher the deployment density of locators, the higher the positioning accuracy. Any wireless positioning technology will have positioning errors and uncertain factors. We suggest that in practical applications, taking into account the characteristics of wireless positioning, the uncertainty of accuracy should be solved through software. There will be jumps during positioning, because the positioning position is in the middle of several positioning points.
The hospital environment is complicated. In some places, it is necessary to judge the situation inside and outside the door or the high-precision position of about 1 meter. We can use the dual-frequency tag 125KHz to trigger the activation.
The positioning frequency can be set to 1 second or more. The web page refresh time is 1 second. Network transmission will also consume a certain amount of time. In order to avoid the interference of the human body on the positioning accuracy, special adjustments have been made to the positioning algorithm, so there may be a delay of 3-6 seconds. Although the number of AP locators will be large, the cost of AP locators is low, can be centrally managed, and can be powered by POE. The wireless transmission function of the AP locator can be disabled, so a large number of AP locators do not generate any wireless signals, which is different from ordinary APs and will not cause wireless interference.
5.3 AP deployment principle
Before determining the number and location of specific nodes, first consider the location requirements and determine the location area and specific room information. The peak number of terminals at each location point and the throughput capacity of each AP must be considered. According to the power of the AP, determine the effective signal coverage of the AP, and ensure that among the AP signals received by any positioning point within the coverage, at least 3 APs have RSSI values greater than -70, and at least one AP The RSSI value should be greater than -50. The AP should be installed reasonably according to the actual geographical environment. The specific layout varies from place to place. It is recommended to arrange every 3 APs. Generally, the simultaneous client scanning capability of each AP is between 100-200, and the throughput frequency is 0.5 milliseconds. Based on the above parameters, reasonably determine the location and installation quantity of APs.
6 Practical case-mobile outpatient infusion management system
In a hospital in Hangzhou, according to the needs of digital hospital construction, following the hospital’s existing infusion process specifications, using advanced, safe and convenient “mobile computing technology” and “mobile identification technology” to help nurses eliminate error-prone links in the infusion process. Solve potential safety hazards.
1. Outpatient infusion management system requirements
(1) Through data sharing with the HIS system interface, the infusion system calls the prescription information, generates and prints a bar code infusion label;
(2) Establish a queuing system and enhance the waiting sequence of patients;
(3) Use PDA handheld mobile devices to collect and verify data, establish a bar code verification method for the whole process of infusion and bottle receiving, and enhance the accuracy of matching patients and drugs; eliminate hidden dangers of error;
(4) Establish an infusion seat management system to keep abreast of the real-time use of seats to facilitate scheduling;
(5) Establish a wireless call for help system for patients to facilitate nurses to obtain information about patients for help and the location of patients in a timely manner;
(6) Realize the mobilization, real-time and barcode verification of nurse business processing.
2. New infusion business process after system implementation:
(1) After the patient’s medication and infusion form information is collected at the infusion reception, the nurse swipes the card or enters the infusion number, and the computer prints the patient’s medication barcode label and the corresponding infusion patient identity check label—two labels, one is A label is attached to the outside of the drug (including the label for infusion queue calling), and one page is the corresponding identity check label for the infusion patient (including the label for infusion queue calling).
(2) The nurse hands the identity check label (including the label for the infusion queue call number) of the infusion patient to the patient, and the patient waits for the infusion according to the infusion queue information displayed on the call screen. Allow patients to estimate the waiting time for infusion according to the call order, reduce the environment noisy, and avoid nurses yelling for infusions;
(3) The nurse scans the patient’s drug barcode label, and the system automatically calls the patient’s queuing number. After the patient is in place, the nurse scans the patient’s identity label for the infusion and performs the infusion after verification. The computer automatically assigns the appropriate seat number for the patient (or the patient chooses it through the touch screen). The printed seat number label is handed over to the patient as an allocation voucher to avoid the chaotic environment caused by the patient vying for a seat. At the same time, the nurse gave the patient a wireless calling unit (WiFi tag) with a call button. The patient’s identity has been bound to the tag in the system;
(4) When the patient has uncomfortable reactions in the infusion, or needs to call the nurse for help after receiving the bottle or the infusion, the patient makes the call through the wireless calling unit (call button) in the hand; the call information and location information can be sent to the infusion room LED display Screen, you can also choose to call the mobile computing terminal in the hands of the inspection nurse; the nurse checks the patient’s infusion information on the PDA and prepares for receiving the bottle (such as: take the second infusion, etc.);
(5) Before the patient accepts the bottle, the nurse uses the mobile computing terminal to scan the patient’s identity barcode label and the drug’s barcode, which can realize fast and accurate identification, ensure that the correct patient receives the correct infusion, and prevent errors;
(6) After the patient’s infusion is completed, the nurse needs to scan the patient’s identification barcode label to confirm that the infusion has been completed. At this time, the system automatically reactivates the seat;
(7) When the nurse is off duty or when the nurse on duty transfers to the shift, a statistical table of the work status of each nurse or the entire class of nurses is generated. The statistical table contains the name of the nurse, job description, time stamp, etc.
3. System configuration list
The outpatient infusion mobile management system includes basic equipment and software. The main equipment and system configuration list are as follows:
Serial number equipment name quantity remarks
1 Wireless smart antenna 4
2 Wireless switch 1 8-port wireless switch
3 Enterprise digital terminal 6 Including charging base
4 Wireless calling unit 230 WiFi positioning label
5 Wireless AP locator 12
6 Ordinary switch 1
7 Location server 1
8 Infusion system software 1
9 Scanner 1
10 Zebra barcode printer 1
11 Label 80*50 10
12 LCD monitor 1
13 HIS interface 1
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