MEDICAL TELEMETRY SYSTEMS
Placement of antennas in patient rooms with telemetry communication Good radio wave transmission
Whip antenna (for patient room)
Ceiling panels (non-metal)
Toilet
Securing the path of wires through beams
Ensuring safe distance 50 cm or more
Cable
Lighting equipment (electrical)
Patient room Corridor
Whip antenna (for a corridor)
Door (steel)
Deck plates (steel)
n Good communication n Poor communication Bedside monitor/transmitter.
equipment but antennae are treated as supplies. This can result in problems such poor reception of the signals transmitted in a medical telemetry system, most often because of inappropriate antenna location. Typical elements of this problem are shown in Figure 1. Poorly or not received signals in a
medical telemetry system can cause serious accidents, such as not recognizing a patient’s deteriorating situation because vital signs are not received accurately or in a timely manner. Modern hospital architecture requires designs and procedures that take into consideration the use of ICT from the earliest stages. To ameliorate such problems, the
Architectural Institute of Japan (AIJ) set guidelines for hospital architecture and construction in September 2021 in cooperation 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 of the guidelines The guidelines consist of 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 matters to be avoided in the planning, design, construction, and evaluation of buildings in order 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.
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Suppresses unwanted electromagnetic interference to and from areas outside the room (downstairs)
Figure 1. Points to be considered concerning where cables and antennae are located.
A typical structure of a medical telemetry system is shown in Figure 2. The frequency of the radio waves used is within the range of 420 MHz to 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 In 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 should be made appropriately. In order to ensure proper 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, construction materials and fittings to be used, and equipment and devices in close proximity.
Antenna system (in the ceiling) Japanese medical telemetry systems
employ at least two different types of antenna system: one uses whip antennae and the other uses 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. 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 construction 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.
Amplifier
Door (steel)
Transmitter Corridor Patient room
Central monitor Staff station
Figure 2. System configuration of a typical Japanese medical telemetry system. IFHE DIGEST 2022
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