The introduction of ICT into hospitals is progressing explosively, but this has led to numerous challenges for the engineers and administrators involved in facility construction. According to a survey by Japan’s Ministry of Internal Affairs and Communications (MIC), about 50% of Japanese hospitals (those with inpatient facilities of 20 beds or more) have medical telemetry systems, and more than 88% have wireless LANs.1 However, more than 40% of hospitals that have implemented these systems have experienced problems related to wireless communication.
The most common reason for this is problems related to radio wave propagation – including such problems as the necessary signals not being able to reach the intended area. Over 56% of the hospitals surveyed by MIC responded to a question about the management and operation of equipment that uses radio waves by saying that they had no staff with sufficient knowledge for the management and operation of their wireless communication system.
Proper wiring installation essential
For the stable and safe operation of ICT-based systems, it is essential that wiring and equipment installation be undertaken properly. Especially in wireless communication, signals of the required intensity must be able to be successfully received. Among the key considerations in achieving this are securing sufficient space for appropriate antennae and wiring, and ensuring that radio waves reach the terminals and antennae at the appropriate intensity. Architecture plays an extremely important role in the efficient operation of ICT systems
The rapid growth in the use of sophisticated digital and other hospital communications systems poses significant challenges, both when designing a new building, and reconstructing older ones. Knowing as much as possible about emerging technologies, and designing the building in a way that accommodates them to the greatest extent possible, are key. Engineers cannot foresee the future, but it is important to build sufficient flexibility into the design and construction of new buildings to allow for the introduction of new technologies.
The process for building a hospital is often as follows: after the design phase, the skeleton is constructed, the air-conditioning system is installed, and the interior is put in place. The telecommunication equipment is then installed, followed by the installation of equipment and fixtures. When building a large hospital, the fact that these various element are undertaken separately can cause some issues.
Poor reception
In ICT systems that use wireless communication, such as medical telemetry systems and wireless LAN access points, cables are often treated as equipment, but antennae as ‘supplies’. This can result in problems such as poor reception of the signals transmitted in a medical telemetry system, most frequently due to inappropriate antenna location. Some of the issues most commonly seen with such a set-up are shown in Figure 1.
Poorly received or unreceived signals in a medical telemetry system can cause serious accidents, for instance if a patient’s condition deteriorates because vital signs are not received accurately or in a timely manner. Modern hospital architecture requires designs and processes that take into consideration the use of ICT from the earliest stages. To address this issue, the Architectural Institute of Japan (AIJ) set guidelines for hospital architecture and construction in September 2021 in conjunction with the Healthcare Engineering Association of Japan (HEAJ), the Electromagnetic Compatibility Conference Japan (EMCC), and MIC. The following is an overview of these guidelines.
Outline, purpose, and scope
The guidelines are set out in six chapters: Purpose, Outline of Medical Telemetry, Scope of Application, Design, Construction, and Evaluation. Our purpose in promulgating these guidelines was to indicate points that should be noted, and steps to be avoided, in the planning, design, construction, and evaluation of buildings to ensure the stable operation of wireless communications for medical telemetry. The medical telemetry systems covered by the guidelines are limited to equipment that meets the criteria of the Radio Law of Japan, RCR STD-21, established by the Association of Radio Industries and Businesses (ARIB) of Japan and JIS (Japan Industrial Standard) T 1304. The typical configuration of a medical telemetry system is shown in Figure 2.
The frequency of the radio waves used is within the range 420 MHz-450 MHz, and in this range six bands are defined. One channel with a bandwidth of 8.5 kHz is assigned to each monitored subject (patient), and the patient is identified by the channel. The output power of the transmitter on the patient side is 1 mW in Japan.
Points to be considered in the design stages
At the basic design stage, information on installation requirements and building plans should be shared among the parties concerned (architectural designers, hospital personnel, and medical device manufacturers and distributors), and plans for antenna placement, wiring routes, and the radio wave environment in the building, made appropriately. To ensure a high quality design, consideration should be given to the patient’s range of movement and the antenna’s communication range, the antenna’s placement and wiring path, the construction materials and fittings to be used, and the equipment and devices that will be in close proximity.
Japanese medical telemetry systems employ at least two different types of antenna system: one uses whip antennae and the other leaky coaxial cables. Hospital personnel should decide on the specific medical telemetry system to be installed as early as possible. The architect will need to plan the building based on as much specific information as possible, such as the range of movement of patients wearing transmitters, and the type(s) of antenna to be employed.
Through the cooperation of the medical equipment manufacturers and distributors in the design implementation stage, the medical telemetry system and related equipment and devices should be coordinated to eliminate the possibility of mutual interference, and the placement of each device should be carefully studied.
Install antennae before constructing the ceiling
The points to be considered in the planning of antenna placement and the wiring route are almost the same as those to be considered in the basic design. It is desirable to install the antennae before constructing of the ceiling, but even if the installation work is done after construction, it is important to ensure that the wiring route is such that the antenna wiring can be easily installed
Points to be noted during construction
At the time of installation, medical device manufacturers and distributors should inform the installer of their requirements for antenna placement, the wiring route, and other needs particular to their devices in order to prevent signal reception disturbance during installation. The designers and installers must pay special When undertaking the wiring work, it is important to confirm on site that a safe distance is kept between the antennae and metal objects such as air-conditioning ducts, and between wiring and electrical equipment that might be possible sources of electromagnetic noise radiation that could affect the performance of the antenna. In addition, because it is likely during the construction phase that there will be changes in the location and number of wiring conduits and pipework planned at the design stage, any changes need to be clearly communicated to all parties concerned, to ensure that the changes can be correctly made. With the pipework, once the wiring for the medical telemetry system is completed, it is important to ensure that the compartment is fire-proof, and that there is adequate insulation.
Evaluation of communication quality as per the guidelines
It is important that the hospital staff check and pass along information on the radio wave environment before and after the installation of antennae. What is key here is to prevent radio wave transmission issues, and investigate any existing problems, such as poor reception, and then determine the best way to respond to them.
Our guidelines recommend the measurement of the radio wave environment before and after the installation of antennae. There are also specific guidelines for the method to be used – including the measuring equipment to be used, the number of measurements, the frequency band to be measured, the measurement procedure, the measurement location, and the method used to set out the results.
The purpose of conducting a radio wave environment survey before positioning the antennae is to confirm the presence or absence of radio waves from other facilities in the vicinity, or within the same hospital, as well as radio waves from other wireless devices that use the same frequency band as the medical telemetry system, and then to provide the key information on the radio wave environment to the relevant hospital personne
Use of a spectrum analyser
During this work, a spectrum analyser and an antenna are used as the measurement devices. The procedure is as follows: set up the antenna at the measurement point, and measure the intensity of the electric field using the maximum value hold mode of the spectrum analyser, with the polarisation of the antenna horizontal and vertical. After the antenna has been installed, the purpose of the further testing is to confirm that the signal can be received with sufficient intensity when the transmitter is moved within the expected movement range of the patient.
The guidelines set out the specifications of the survey method to be used prior to the start of service. The radio wave survey uses a handheld transmitter that will be affixed to the patient, and a spectrum analyser, as the measurement tools. The transmitter is moved sequentially to the transmission points designated to cover the expected travel range of the patient. At the ‘central monitor’ at the staff station, the signal intensity and C/N (carrier to noise) ratio of the portable transmitter at each transmission point are measured, by connecting a spectrum analyser to the coaxial cable from the antenna using a signal splitter.
Changes over time
It is known that the radio environment received by a central monitor changes during long-term operation. Factors that cause these changes include wireless communication devices brought in by patients and visitors; newly introduced medical equipment; components such as antennae, amplifiers, and distributors, and deterioration in the condition of the coaxial cables connected to the central monitor.
There could also be deterioration of the entire system over time. The Japanese guidelines thus also stipulate the method for evaluating the reception status after the service has been put into operation. The process employed is basically the same as that used before the medical activities in the hospital commence, but it is described in the guidelines with special consideration to comparison points.
Conclusion In conjunction with the publication of these guidelines, the EMCC is now revising its Guide for Safe and Secure Use of Radio Waves in Medical Institutions, which was published in 2016.2 We are also planning to develop new guidelines for the proper installation and operation of wireless LANs. We hope that the establishment of these guidelines will lead to the sharing of information among those involved in building hospitals, hospital personnel, medical equipment manufacturers and distributors, and other stakeholders, and to the development of a safe and efficient wireless communication environment in medical facilities, thereby improving patient safety and labour efficiency in hospitals.
References
1 Electromagnetic Compatibility Conference Japan. Results of the FY2019 Survey on the Promotion of Appropriate Radio Wave use in Japanese Medical Institutions, etc. (Hospitals), 2020.
2 Electromagnetic Compatibility Conference Japan. A Guide for Safe and Secure Use of Radio Waves in Medical Institutions, 2016.
This article, titled ‘Guidelines for medical telemetry systems’, was originally published in the IFHE Digest 2022. HEJ thanks the IFHE, the author, and the Digest’s editor, for allowing its reproduction here in slightly edited form.
Tetsuo Endo
Tetsuo Endo is a manager at the Taisei Advanced Centre of Technology of Taisei Corporation in Japan. He chairs the Electromagnetic Environment Steering Committee of the Architectural Institute of Japan, and the sub-committee on investigation of guidelines and descriptions for medical institutions with building plans considering the use of radio wave equipment.
Takashi Kano
Takashi Kano is project professor at Jikei University of Health Care Sciences, and Professor Emeritus of Saitama Medical University in Japan. He chairs the Committee for Radio Use Promotion in Medical Institutions of the Electromagnetic Compatibility Conference (EMCC), supported by Japan’s Ministry of Internal Affairs and Communications (MIC). Guidelines for medical telemetry system use in Japanese hospitals are based on the results of this committee’s activity.
Eisuke Hanada
Eisuke Hanada is a Professor at the Saga University Faculty of Science and Engineering in Japan. He previously worked at the Nagasaki University Information Science Center, at the Division of Medical Informatics, Kyushu University Hospital, and at the Division of Medical Informatics at Shimane University Hospital, as vice-director. He chairs the specialised research group on electromagnetic environments in clinical/welfare settings of the Japanese Society for Medical and Biological Engineering, and is a board member of the Healthcare Engineering Association of Japan.