Medical Applications of Wireless Networks

Transcription

1 Ranjana R.Chittal M.Tech(C.S.E), Dept. of C.S.E, R.V.C.E, Bangalore Medical Applications of Wireless Networks Dr. Shobha G Assistant Professor, Dept. of C.S.E, R.V.C.E, Bangalore shobhatilak@rediffmail.com Kamod Kumar M.Tech(C.N.E), Dept. of C.S.E, R.V.C.E, Bangalore kamodkumar@gmail.com Abstract Sensor based technology has invaded the medical devices with a wide range of devices available today with wireless network capability, which have the potential to replace thousands of wires connected to devices found in the hospitals. This technology has the capability of providing the reliability with enhanced mobility. It is being looked upon as alternative solution to provide low cost medical solution along with enhanced accessibility to the patients in view of permanent usage of wireless devices. In this survey paper background of applications of wireless networks in the medical field and the issues and challenges involved in this technology transforming lives of several people who are deprived of quality health care facilities are discussed. Finally architecture for this communication system is discussed. Keywords: wireless medical applications, architecture for medical wireless network, issues & challenges 1. Introduction Wireless sensor network[1] is an emerging technology consisting of small, low-power, and lowcost devices that integrate limited computation, sensing, and radio communication capabilities. Minimal configuration and quick deployment make adhoc networks suitable for emergency situations like natural or human-induced disasters, military conflicts, emergency medical situations etc. This is a promising technology which can improve the healthcare industry and it is finding its way into various aspects of our life. Sensor devices can be used to capture continuous data from patients in real time and communicate to doctors & Emergency Medical Technician staff (Nurses & Technicians) on their hand held devices. This technology can prove vital in mass casualties and natural disaster where patients records like identification, previous medication history and other vital information can be stored. This technology is expected to reduce the amount of time the doctors require to identify the problem and consult fellow doctors through use of hand held devices communicating in ad hoc mode. Also this will reduce the amount of paper work required and the duplication of patient records. Ad hoc network facilitates creation of network of medical devices on the fly (Sensor network) thereby supplementing the resources at hand by providing features like reconfiguration and reallocation similar to HAM radios in use today. The devices use minimal power and are robust which decrease their dependence on available infrastructure (resources like electricity supply, communication infrastructure like telephone lines etc which are target of insurgents or are destroyed by natural disaster) and this makes them an attractive alternative. However this technology has a limitation as the ranges of these devices are fixed and to enable the services to be extended to large geographical areas like ambulances and patient premises requires this infrastructure to interoperate with other wireless networks like GSM /CDMA mobile networks. Thus, we are looking at a new technology which is born as a result of fusion of medical sensors and mobile technology. This technology promises to reduce the number of visits required by patients for health checkup by allowing the doctors to remotely monitor the patients and advice them. Life insurance companies can collect the data from the database to settle the medical claims. With all this discussion of wireless applications, healthcare providers such as hospitals, insurance agencies and the government are becoming interested in investing in this area. Cost saving is one of the main factors because medical errors by doctors bring in law suits and patient and hospital management and be very expensive too. This has drawn a lot of attention of both researchers and industry.

2 This survey starts with a discussion on wireless technology and then looks into the proposed architecture. Then the various challenges and future trends are explored. 2. Wireless Technology In order to avoid contamination most of the hospitals ban entry of unrelated items including people in the critical wards and Intensive Care Unit. This is primarily done to avoid contamination and infection. One aspect which is not taken care of in this regard is the contamination caused by the use of large number of cables running in these rooms and interconnecting the devices. It is neither possible to remove these wires nor avoid them from coming in contact with patients. A suitable alternative to this problem is to make these devices communicate without wires through wireless communication. Wireless communication has evolved over the period of time such that it is now capable of providing high data rates & reliability for short ranges. Technologies like Bluetooth [2], PAN and WLAN have already proved their might and are widely in use today. Research is also carried on creating mobile trauma systems using the wireless channel. This will potentially allow trauma specialist to be virtually on patients bed sides while they are being moved to the trauma centre. Another issue that concerns the healthcare field is the large number of tedious routines that are involved in translating results from one machine to another which are expensive as well as incompatible with each other. With Wireless Technology this compatibility issue can be reduced There is a new facet of this technology that has emerged in the last few years. This issue is related with the wearable wireless implants that the patients can be fitted with and these can collect the data through their sensors and relay this data to the hospital through wireless communication. This technology will address the issues regarding the access wherein patients need no longer move around the hospitals for regular checkups. 3. Potential Medical Applications All the applications of wireless networks can be broadly classified as follows- [a] Real Time Continuous Patient Monitoring Pre hospital, In hospital and ambulatory monitoring. These applications are basically concerned with the monitoring of vital signs and recording the various statistics of the patients. They can be thought of as a simple replacement of wired medical equipment like ECG, etc. [b] Home monitoring for Chronic and Elderly Patients Collect periodic and continuous data and upload it to the doctors Allow long term care and trend analysis & most importantly reduce the hospital stay. All these applications are designed with the intension to reduce the stay of patients in the hospitals except for the time required for procedures. This facilitates the physicians to monitor several patients virtually in the same time which could not be achieved if patients are hospitalized. [c] Collection of long-term databases of clinical data Correlation of Bio sensor reading with other patients information Longitudinal studies across the populations and incorporation of study effects of interventions and Data Mining. These applications are basically concerned with the study of epidemic and issues relating community health. The most important use of such a network would be in case of large accidents, fire or natural disasters like floods or terrorist attacks. In all these scenarios the normal community services may be damaged or destroyed leaving a large number of patients which can cause severe load for the emergency personnel attending the casualties. Since the core communication infrastructure is completely destroyed or damaged and or because of large number of casualties the only way of tracking them is through papers and reports with manual identification of each of them. The sensor networks concatenated with other wireless technologies have the potential to affect the large number of casualties by providing a means of real time continuous monitoring of vital systems of patients. Each patient is provided with a tag for his/her identification which can be used to identify him/her and study his/her previous medications. The emergency staff has the provision to keep a watch on the patients who require immediate attention upon receiving alerts from changes in the health status. This can also be relayed back to the hospital where the patients are being moved so that the doctors have the opportunity to correlate the data and identify the procedures for the patient. 4. Architecture and Services The architecture of Sensornet based wireless medical [1] device consists of an information plane which provides coordination and communication across the wireless medical devices. The communication model comprises of Publisher-

3 Subscriber data delivery model where the sensor nodes publish vital signs, location information, its identity etc. Rescue personnel and others can subscribe to this information depending on the area of interest and receive the subscribed information. Fig 1 shows the proposed architecture which is an extension of the architecture proposed for codeblue [1].The extension comes in the form of a Convergence Layer similar in functionality to the IMS [3]. The requirement that this architecture addresses to is the communication between the various devices through the other wireless technology which allows PDA s, Mobile Phones (Smart Phone) and other hand held devices. This design allows diversified architecture to combine to provide communication with Medical Sensornets. Another issue that is addressed by this architecture is providing a mechanism for high data communication which would enable doctors to provide prescription & consulting along with real time monitoring the patients There are various protocols which are used in this architecture to enable reliable communication of data. Protocols address the issues like addressing-naming, Authentication Encryption, Event delivery, Filtering- Aggregation, Handoff- Hard/Soft, etc. Naming Discovery Authentication Encryption Information Plane Event Delivery Convergence Plane Filtering Traffic Aggregation Handoff Fig1. Proposed Communication Architecture-Convergence of Technologies The use of ad hoc networking will allow the mesh of connectivity to extend across an entire building or between multiple, adjacent facilities. Additional coverage, if necessary, will be possible with placement of fixed nodes in hallways, rooms, or other areas. No matter the topology, the network will be selforganizing: loss of a given node or network link can be rapidly detected and data re-routed accordingly. It can provide for reliable transmission of critical data through content-specific prioritization and dynamic scaling of transmission power. 5. Research Challenges There are a number of issues that are identified in this survey so as to make the technology acceptable for medical applications [4]. The prime objective of course is to develop a wireless solution which can be reliable and fault tolerant. The research areas can be classified as explained under [a].[b] & [c] as follows: [a] Communication Challenges The first and foremost issue is to provide a mechanism for secure and reliable communication among the various groups of sensors, handheld devices & mobile. Sensor networks are self organizing and operate with low power and very little computational resources. There is a limit on the type and complexity of application data that these devices can operate on. Second issue is the prioritization of critical data which require immediate attention of medical professional. Convergence of communication architecture and security issues with regard to various devices is equally important. Since these devices work with short range transmitter and receiver, a method needs to be devised for making sensor networks utilize the available GSM/CDMA infrastructure to enable communication between two peers separated by large distance. [b] Computational Challenge: Sensor nodes have very limited computational power, and traditional security and encryption techniques are not well-suited to this domain. While secret-key cryptographic systems have been demonstrated on motes, there is currently no practical means of establishing encryption keys. The use of efficient, integer-based elliptic curve cryptography is explored which has the potential to allow rapid rekeying among groups of sensors. The system must allow physicians, nurses, and others to assign access rights to patient data quickly and determine handoff credentials when a patient is transferred to another unit or hospital. Existing authentication systems are extremely rigid in this regard. [c] Programming Challenge Finally, coordination of a diverse array of sensors, active tags, handheld computers, and fixed terminals requires a cohesive communication and programming model to underlie the system s operation. Existing software for sensor nodes is in a very low-level and does not provide higher-level services such as discovery, naming, security and data delivery within a common framework. Our goal is to develop a flexible

4 protocol suite for integrating a range of wireless devices in a critical care setting. Some main issues that arise due to the use of wireless networks devices include security, privacy and the learning curve for new technologies. Ensuring patients information security can be a major issue when deploying these applications. Privacy of user data over wireless channels can be another major issue. Wireless networks based medical devices can be very limited in terms of power availability and processing strength. Thus ensuring privacy without using complex encryption algorithms can be a big issue for developers of medical devices. With the new technologies pervading in our daily lives, new users can find it challenging to use these new devices to the fullest. Thus it can be an issue and a challenge for developers to create some of the best solutions without forcing the users to make unnecessary of effort just to learn how to use them. 6. Standards Although the area of wireless networks for medical applications is largely without standards due to companies developing products based on their own standards, there do exist some standards and the same have been listed a few below. Recently, the demand for creating strict standards, especially for pacemakers, which are being used by a large number of heart patients across America, has increased. IEEE Standards Medical Device Communications / Health Informatics Standards Subscription o ISO/IEEE Health informatics - Point-of-care medical device communication o IEEE Standard for Medical Device Communications-Transport Profile Mobile Health Care Alliance o Setting standards for mobile health information systems Medical Implant Communications Service in the MHz band o High-speed, ultra-low power, nonvoice transmissions to and from implanted medical devices such as Cardiac pacemakers and defibrillators. 7. Research Applications This section discusses about some special applications that have been developed or are currently being developed in the research community for the purpose of healthcare improvements. Some these medical applications have impacts in daily social life, while others have pure medical benefits. A list of other applications can be found in the manufactures websites [5-7] 7.1 Code Blue CodeBlue [8] is a sensor network based medical research project being developed at Harvard. Specific goals for this project include pre-hospital care and inhospital emergency care, stroke patient rehabilitation and disaster response. Research from this project has potentials for resuscitative care, real-time triage decisions and long term patient observations. This project has hardware as well as software parts. Fig 2 shows a Mote based pulse oximeter which is a Wireless Vital Sign Sensor which forms a part of hardware. Fig2. Mote-based pulse oximeter. Some devices and software produced in the project include * Wireless Vital Sign Sensors * Wireless two-lead EKG [Jones04] 7.2 Project Connect The Connect project [9] is basically focusing on creating solutions to help people with disabilities in their day-to-day life. They are trying to create a distributed wireless communication infrastructure that allows for individual customization of portable devices such as a PDA. Initially the project relied on GPRS for communication between the PDA devices and the central server. The main aim of the project is to enable people with disabilities to customize their wireless

5 devices i.e PDA to keep schedules for them, give them important reminders and allow them to communicate with their caregivers through any of the several possible ways provided. Therefore this system adapts to the user's needs Industrial Applications LifeSync Wireless ECG System Fig3 : Wireless ECG Transceiver LifeSync [10] Wireless ECG System is a basic ECG device that operates using Bluetooth wireless technology. It can collect patient ECG and respiratory data and transmit using two-way radios. Fig 3 shows a set of transceivers that are used within hospital and ambulatory service. The main goal with this device is that it will provide a more mobile interface to existing ECG monitors in Hospital. The device can be placed anywhere while the results shown in conventional monitors. One of the advantages with using this device is that it includes continuous monitoring in a mobile environment and also that they are designed to interface with existing medical devices. This will somewhat reduce the reluctance of hospitals to phase out old but expensive machines. These devices can provide a more efficient and modern standard interface to such expensive machines. communicating over the air. Currently the wireless technology used 8 Summary Wireless networks for Medical Applications is becoming a hot topic in the industry. With its potential uses in the medical and home healthcare fields, wireless networks have an important contribution in improving lives of patients. Besides bringing comfort to patients, there are large commercial benefits in the area of reducing costs and improving equipment and patient management. In this survey paper, we discussed the benefits of using wireless networks for medical applications. We talked about how these new technologies can be used to potentially reduce costs for hospitals, government and insurance companies. With wireless networks-based medical technologies, applications can be designed to be less intrusive in patients' daily lives. All applications based on scientific methods have a development lifecycle. This is normally starting out with a research project and moving onto commercialization. Lessons learned here are applied when designing newer applications in the future. We talked about current and past research projects. We also brought in some commercial applications that are currently available in the market. Some of these products are very innovative and have chances of succeeding. With all new technologies, there are chances of failures and success. Some of the projects that we talked (i.e CodeBlue) about are long term project and parts of them have already made the transition to commercialization. Homecare is an area where wireless networks for Medical Applications have the most potential. Smart home [12] based technologies are being designed which will eventually care for our elderly and patient who need long term care Airborne(TM) Embedded Wireless Device Server Modules and Radios [Airborne(TM)[11] modules are an answer to integrating old machinery with latest wireless technology. Instead of phasing old but still useful and functioning medical devices, these interface modules will allow hospitals and clinics to make them useful and last much longer. One of the main drawbacks of using the heavy and expensive machines in hospitals is that once placed in a room, they belong to the room and the room belongs to them. These interface modules will allow hospitals to reduce wiring and incompatibility issues because machines will start

6 9. References [1] D. Malan, T. Fulford-Jones, M. Welsh, and S. Moulton, "Codeblue: An ad hoc sensor network infrastructure for emergency medical care." In Proceeding of the International Workshop on Wearable and Implantable Body Sensor Networks, [2] Nicolas Chevrollier, Nada Golmie, "On the Use of Wireless Network Technologies in Healthcare Environments", July 2005, White Paper - U.S Department of Commerce [3] IMS Architecture & Specification [4] J. A. Stankovic, Q. Cao, T. Doan, L. Fang, Z. He, R. Kiran, S. Lin, S. Son, R. Stoleru, A. Wood, "Wireless Sensor Networks for In-Home Healthcare: Potential and Challenges", in High Confidence Medical Device Software and Systems (HCMDSS) Workshop, June 2-3 Philadelphia, PA, pdf [8] Victor Shnayder, Bor-rong Chen, Konrad Lorincz, Thaddeus R. F. Fulford-Jones, and Matt Welsh. "Sensor Networks for Medical Care", Harvard University Technical Report TR-08-05, April [9] Project Connect d=353 [10] GMP Wireless Medicine, Inc. [11] Airborne(TM) Embedded Wireless Device Server Modules and Radios [12] Smart Home Automation [5] A&D Medical / Lifesource [6] Nonin Medical, Inc. [7] HealthFrontier, Inc.