Radiofrequency interference with medical devices: practices should be adapted to each situation

The use of mobile telephones in hospitals was addressed in a Circular of October 1995 warning of the risks of electromagnetic fields emitted by mobile telephones interfering with medical devices. It invited health establishments to inform their staff and patients of this potential hazard and insisted on the need to switch off mobile telephones in healthcare services.

In 2003, a study by the Committee for the Evaluation and Dissemination of Technological Innovations (CEDIT) indicated that the interference caused by the use of mobile telephones would not affect medical devices if they were more than 1.5 m away and was not hazardous for people with active implanted medical devices, on condition that certain precautions be taken. These conclusions have in some cases led to the relaxing of bans within certain health establishments.

At the same time, the use of mobile telephones has become commonplace within hospitals, whether by health care professionals, including for certain professional applications (emergency calls, alarms, etc.), or by patients or their families. The recommendations made on the basis of the Circular of 1995 thus appear to be applied less and less.

In this context, the Directorate General for Health and the Directorate General for Risk Prevention formally requested ANSES to issue an opinion on the potential risks of electromagnetic interference with medical devices exposed to radiofrequency radiation and propose, if appropriate, minimum safety distances to be respected according to the different sensitivities of medical devices.

The Agency's work

ANSES's expert appraisal focused on the electrical and electronic medical devices used in hospital care services, as well as on active implantable medical devices (pacemakers, neurostimulators, etc.) used outside these services.

The sources of electromagnetic fields considered were the mobile communication systems of caregivers, patients and their families: mobile telephones, Wi-Fi and Bluetooth devices, DECT (Digital Enhanced Cordless Telephones) and walkie-talkies, especially TETRA type (Terrestrial Trunked Radio) and RFID (Radiofrequency identification) technologies. The mobile telephone is potentially the greatest source of exposure to radiofrequency radiation, in terms of intensity, among all the radio sources to which the population is routinely exposed.

The Agency’s recommendations

Given the extreme diversity of both the sources of electromagnetic fields (characteristics relating to frequency, power, signals, etc.) and the electronic medical devices, in addition to the different exposure situations involving medical devices, it is not possible to define a single rule, applicable to all situations, concerning a minimum distance to be respected between the medical devices and the electromagnetic sources.

Medical devices in a hospital environment

The ban on the use of mobile telephones and other personal communicating devices in healthcare establishments seems unjustified. The establishment of areas where use is authorised, limited or prohibited is recommended. Each hospital should be responsible for the precise definition of such areas, supported by their head of risk management.

The Agency recommends that health establishments implement measures to minimise the risk of interference with medical devices:

• with regard to patients, visitors and medical staff using mobile telephones for personal reasons: mobile telephones should be switched off in places with critical medical electrical devices or those used for life support (intensive care units, operating theatres, neonatology, emergency services, etc.), as well as near the beds of patients connected to medical electrical devices;
• with regard to medical staff using their mobile telephones for professional reasons: telephone calls should not be made near medical electrical equipment.

To the extent that the use of DECT telephones generates lower exposure than mobile telephones, the Agency recommends that medical professionals give preference to the use of this means of communication.

Active implantable medical devices

The Agency recommends that wearers of active implantable medical devices (cardiac implants, pacemakers, etc.) ensure that they keep their devices away from the greatest sources of exposure (mobile telephones). Thus, the recommendations in the information booklets or instructions for use must be applied, particularly concerning the distances to be respected if mobile telephones are used (do not put the telephone in a pocket near an implant, make calls with the telephone held to the opposite ear, etc.) or when passing through security gates (anti-theft, airports).

Stakeholders in the healthcare chain (manufacturers of medical devices, health professionals) should also be trained to ensure that they convey these messages to patients and their families, in particular the precautions for use recommended by the manufacturers.

Lastly, the Agency considers that just like hospital practitioners, other health professionals who use electrostimulators (physiotherapists, for example) should receive training to help them analyse the benefits/risks for patients associated with the practice of certain treatments or diagnoses involving the close proximity of an active implanted medical device and a transmitter of radiofrequency radiation.