Abstract
National recommendations in Sweden recommend a safety distance of 3 meter (m) between mobile phones and medical-electrical (ME) equipment in hospitals. A questionnaire was used to investigate how often mobile phones were reported to interfere with ME products in clinical practice across Sweden.
The results confirmed that ME equipment can be affected by mobile phone use but, the risk of the patient’s outcome being affected were minimal; no cases were identified which led to injury or death.
In conclusion, the results support recommendations for a general safety distance of 0.5 m between mobile phones and ME equipment in care environments.
Background
Use of mobile phones has accelerated in recent years and become a natural part of the hospital environment. Medical staff use mobile phones to seek and share information, as well as to sound the alarm in emergencies [1, 2]. In Sweden, almost all of the inhabitants have mobile phones [3], and as a result, patients, their families and also healthcare providers frequently use private mobile phones in hospitals.
In October 2003, the Swedish National Board of Health and Welfare published recommendations regarding the use of mobile phones in hospitals in Sweden [4]. These recommendations still apply, and specify a safety distance of 3 m between mobile phones and medical-electrical (ME) equipment, which in practice means that use of mobile phones is not allowed at all in hospitals. The underlying reason is the concern that mobile phones may interfere with ME equipment, with potential and possibly serious consequences for the patient.
The 2003 directive was based primarily on testing of ME equipment produced during the 1990s, and there has been an enormous development over the last 25 years. New knowledge about emission-resistant components, and use of surface-mounted components in combination with industrial production of circuit boards has resulted in ME equipment that is less sensitive to interference from mobile phones. Manufacturers have also been made aware via the European Commission Guidelines on a Medical Devices Vigilance System [6]that their products are affected by mobile phones, and for purely commercial reasons, it is highly likely that they build in better electromagnetic protection than standards require.
The literature [7, 8, 9, 10, 11, 12, 13, 14, 15] clearly indicates that ME equipment can be influenced by mobile phone use, but most of the evidence for this comes from rigged test environments. Reported effects generally occurred at distances of 0 to 0.5 meter (m), with only isolated reports of effects between 0.5 and 4 m, and in the majority of cases, the effects ceased when the mobile phone was removed from the vicinity. Both ME equipment and mobile phones of newer models are reported to give less interference than corresponding older models. Only a few reports of mobile phones interfering with ME equipment were related to real incidents with patients in a clinical situation, and the reported cases occurred with equipment manufactured in the 1990s. In the few publications that include recommendations for a safety distance between mobile phones and ME equipment, the recommended distance is 1 m. None of the recommended safety distances that exist are based on clinical cases where patients suffered harm due to interference from mobile phones. A review concluded that there are no evidence-based guidelines for use of mobile phones in care environments [8]. Hence, there is an acknowledged need for such guidelines [10]. Therefore, the aim was to investigate how often mobile phones were reported to interfere with ME products in clinical practice across Sweden.
Methods
In Sweden, the responsibility for the population’s health care is divided between the 21 county councils and the municipalities within the same geographical areas [16], and the project was administered from the Office of Medicinal Service, Region Skåne. A questionnaire was distributed across Sweden to all 21 county councils, and corresponding information was also retrieved from the Swedish national database for registration of reported incidents, Reidar
Date of observed effect (year-month-day) ME product affected (type, manufacturer, and model) Type of effect – critical or non-critical (tick box) Clear or suspected correlation with radio communication (tick box) Type of radio communication (text) Care establishment where the event occurred (name) If possible, a description of the effect (text)
Summary of reported incidents
The instructions for the questionnaire stressed the importance of high quality in the responses, and that they would be used as the basis for an update of recommendations for use of radio-communication. The reasoning behind the questionnaire was that compliance with the current prohibition was suspected to be very poor; healthcare personnel as well as patients and their relatives most likely all carry active mobile phones in care situations where ME products are used. So if mobile phones affect such equipment, it should have been noticed.
The expert validity of the questionnaire was confirmed by an expert panel of 7 persons skilled in information technology or biomedical technology.
Based on the collected incidents with critical or non-critical effect, have events of different levels of difficulty revealed. Effects were defined as “critical” if the diagnosis, treatment, or rehabilitation of the patient was affected, for example a change in the rate of infusion through an infusion pump. Effects were defined as “non-critical” if there was interference in the diagnosis, treatment or rehabilitation of a patient, but the outcome was not affected, for example noise from the loudspeaker of a foetal sound monitor. When the effect was detected through technical testing only, this was to be indicated by writing “technical test”. The result has been supported with quotations that refer to date of incident in order to judge the trustworthiness.
Results
Of the 21 county councils that received the questionnaire, 10 responded. A total of 36 incidents were reported, some of them representing more than one occurrence of the same event, giving a total of approximately 50 events There were 6 types of ME equipment which featured 2 or 3 times in the questionnaire responses; of these, 2 were reported in Reidar
Examples of critical effect
Syringe pump – suspected to have been affected by mobile phone. The pump rate was increased and 2.7 mL additional Oxynorm was infused compared with the 24 h setting (less than 10%). Visitors had mobile phones. (January 2008).
Examples of non-critical effects
Volumetric infusion pump – suspected effect of mobile phone. The alarm on the pump went off – “pump malfunction”. The patient was using a mobile phone (April 2011).
Example of modification guidelines allowing general use of mobile phones
Example of modification guidelines allowing general use of mobile phones
Audiometer – non-critical effect on patient. During measurement of hearing, there was a loud buzzing noise in the earphones when a mobile phone was switched on. (Date: April 2013).
Examples of clear association in technical tests
Blood and fluid warmer with the phone held 0 to 5 cm from the upper part of the display, the temperature alarm went off. (May 2013).
Based on the results a presentation of a modification of guidelines to allow general use of mobile phones with a safety distance of 0.5 m is given in Table 2.
Discussion
The risk of injury versus the occurrence of injury is central to this study. There has been much discussion over the years regarding the potential risk that patients will suffer harm due to mobile phones interfering with ME equipment, resulting in more or less total prohibition of mobile phones in hospitals. This study indicates that while interference with ME equipment can occur, the risk of harm to the patient is very small. This opens up to wider use of not only mobile phones, but also other mobile ways of working with enormous potential in patient care – both from a medical and social perspective. It is time for all parties to take a new perspective on the use of radio communication in all its forms in the care environment.
The present study resulted in a modification of Region Skåne’s guidelines from 1 May 2016 to allow general use of mobile phones with a safety distance of 0.5 m. The reduction in safety distance to 0.5 m naturally needs to be followed by close monitoring, to ensure that it does not result in an upswing of events, indicating that the risk has been underestimated. Additional studies reporting clinical cases where mobile phone use affected or was suspected to affect ME equipment would also help to clarify the extent to which this theoretical concern translates into a clinical concern.
A further factor to consider is that modern medical care tends to involve not only hospital and primary care but also care in patients’ homes, which is a less-controlled environment where patients and their families largely practice self-care. ME technology, including ventilators, various pumps, peritoneal dialysis equipment, and oxygen therapy has become widely used in home health care [17]. This places an important responsibility on manufacturers of ME equipment, and it is something healthcare providers must take into account in risk analyses, and follow up via the vigilance system.
We did not evaluate the benefits of mobile phone use in this study, but it has earlier been stated that communication with mobile phones reduced the risk of medical errors and harm to patients and use of mobile phones in hospitals are recommended [2, 18]. We would welcome further studies evaluating the benefit of mobile phone use and smart applications in health care.
Methodological considerations
Our response rate was relatively low (10 of 21), and it is possible that a better response rate would have been obtained and more incidents identified with different methods. However, our results are in line with literature findings, so it is likely that the conclusions would have been the same. A further weakness is that we did not measure how common it actually was for people to carry active mobile phones in the care environment. Based on our own observations relating to the use of mobile phones in healthcare environments, we assumed that most visitors and medical staff walk around with mobile phones switched on, and it is possible that compliance is better than we thought, contributing to the low rate of reported events.
Regardless of the weaknesses of the study, it can be seen as a first step towards evidence-based guidelines for use of mobile phones in care environments, and we would welcome further similar studies from other contexts and other countries to further bolster the evidence.
Conclusions
This study indicates that the risk to patients from interference of mobile phones with ME equipment is lower than generally feared, and the study supports a general safety distance of 0.5 m in care environments.
Acknowledgments
Special thanks to the participants from LfMT who took part in the survey. Thanks to Christer Törnevik, Director, EMF Safety and Sustainability, Ericsson AB and Peter Kvist, radio network consultant, We-Consulting AB for expert advice on mobile telephony. Medical writing support was provided by Bengt Johansson, funded by the Office of Medicinal Service, Region Skåne, Sweden.
Conflict of interest
None.