Mobile communications interference

Background
Cellphones (mobile phones) and other communication equipment (e.g. radio devices) can be essential in hospitals for good patient management. However, such equipment produces electromagnetic interference (EMI) and this can affect medical devices in an adverse way. This can be a particular problem when mobile communication devices are brought into hospitals by patients, visitors and staff in an uncontrolled manner. Therefore some restrictions are necessary to minimise the risk of interference with critical medical equipment.

MHRA recommendations

* GPRS - General Packet Radio System and 3G (3rd Generation cellular technology) are data transfer radio systems. It is not always easy to recognise a laptop or palmtop that has a radio data card fitted. See the images below. Healthcare staff should familiarise themselves with these data cards to help prevent use in prohibited areas. The GPRS card may in some cases be readily identified by its brightly-coloured casing and may also have a small aerial.

** HIPERLANs - HIgh PErformance Radio Local Area Networks

*** DECT - Digital European Cordless Technology

**** RLAN - Radio Local Area Networks

A type of GPRS card	GPRS card fits into the PCMCIA slot in palmtops or laptops

Cellular technology incorporates dynamic (variable) power output dependent on distance from the base station but radio propagation is so variable, particularly inside buildings, that maximum power should be assumed.

Summary
Healthcare providers should actively manage the use of the radio frequency spectrum in their own sites. This includes considering areas where medical devices will not be affected and therefore no restrictions apply and other areas where authorised staff can use communication devices authorised by the hospital. Report incidents to the MHRA when a medical device is suspected to have suffered electromagnetic interference.

Copies of posters designating mobile use and non mobile use areas are attached for use by trusts as appropriate.

Further technical information
The International Organisation for Standardization (external link) has published a technical report; ISO TR 21730:2005 'Health informatics - use of mobile wireless communication and computing technology in healthcare facilities - recommendations for the management of electromagnetic interference with medical devices'.

Some points taken from this report:

• Misinformation regarding mobile wireless systems, electromagnetic interference and management procedures has led to a broad range of inconsistent policies among healthcare organisations.
• A balanced approach is necessary to ensure that all the benefits of mobile wireless technology can be made available to healthcare organisations.
• Overly-restrictive policies may act as obstacles to beneficial technology and may not address the growing need for personal communication of patients, visitors and the workforce. At the other extreme, unmanaged use of mobile communications can place patients at risk.
• One option involves issuing particular mobile wireless equipment to doctors and staff for healthcare-specific communication and health information access. This would allow the full benefit of wireless technology operating compatibly throughout the healthcare facility, even in sensitive areas in proximity of life-critical medical devices. However this would need to be comprehensively managed, and would involve ad-hoc on-site testing of representative units of all life-critical medical devices in the equipment inventory to characterise any potential health-threatening issues. This is because the variety of medical equipment types makes EMI difficult to predict, and because older equipment is likely to be more susceptible than newer equipment that has been designed according to current radio frequency immunity standards.
• It may not be feasible for healthcare organisations to manage every mobile wireless handset that is randomly brought into their facility without certain restrictive limits.
• Restrictive policies for non-controlled mobile wireless handsets can be facilitated by offering numerous areas that are easily accessed throughout the healthcare facility where the use of mobile wireless handsets by patients, visitors and staff is permitted. Be aware that mobile devices transmit in three dimensions.

Links

• OFCOM (formed by a merger of the former Radiocommunications Agency with other related bodies) now regulates all devices that transmit radio signals and allocates radio spectrum bands: see http://www.ofcom.org.uk (external link)
• IEEE/ANSI C63.18 standard is a suggested test protocol for rapid and practical ad-hoc, on-site EMC testing: see http://www.ieee.org/portal/index.jsp (external link)
• The USA FDA has produced supporting web-based information about testing medical devices - 'FDA/CDRH Recommendations for EMC/EMI in Healthcare Facilities' see http://www.fda.gov/cdrh/emc/emc-in-hcf.html (external link)
• For more information on DECT see http://www.dect.ch (external link) and http://www.dectweb.com (external link)

For further information contact:
Richard Glover, Principal Medical Device Specialist, MHRA
Tel: 020 7084 3245
E-mail: richard.glover@mhra.gsi.gov.uk