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Wireless devices safe if kept metre away from equipment


Wireless devices used by nurses are unlikely to interfere with vital electronic medical equipment if staff stick to simple rules, concludes a new study.

Research by Concordia University in Canada found there was minimal risk of hand-held devices like tablets causing medical equipment to malfunction, providing staff stuck to “minimal separation distance” (MSD) guidelines specified by hospitals.

While hospitals often require staff and patients to switch off devices like mobile phones in certain areas, wireless technology is increasingly being used on a regular basis on the wards to access patient notes and record data.

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A team from the Concordia’s engineering and science faculty used advanced mathematical modelling techniques to assess the risk of electromagnetic radiation from such technology interfering with equipment like heart monitors.

The study, published in the journal IEEE Transactions on Electromagnetic Compatibility, found MSD policies, which generally require devices to be kept more than a metre away from sensitive medical equipment, were effective.

“We found that MSD policy really does work,” said the study’s lead author Medhi Ardavan. “If hospital staff comply with the policy, they can have a tablet in the same room as the patient and medical equipment without posing a danger.”

Extending the MSD beyond a certain point did not necessarily increase safety, the researchers found.

However, they noted that if staff neglected to follow the rules then that could potentially cause problems.

“Hospitals need to be vigilant that staff members obey the MSD rule,” said senior study author Christopher Trueman, a professor in the university’s department of electrical and computer engineering.

“The nature of the problem is that there can never be zero risk, but by complying with MSD the risk can be reduced to a low enough value that it’s very unlikely there will be interference,” he added.


Readers' comments (9)

  • Matthew  Carr

    So stop buying heart monitors that are affected by EM radiation? Big solar storm is going to wipe them all out...

    Already said there's a risk that even keeping a meter away is going to fry the heart monitor.... why take the risk?

    The risk is minimal as it is... has there ever been a recorded instance where a heart monitor has been affected by a modern wireless device? Sure back in the 70's through to early 90's there were reports of devices being overloaded due to EM radiation but that was before regs came in to reduce this effect. The US I know has reduced regs compared to the EU for devices is that reflected in this paper?

    Or is this yet more scare mongering like the reports that wifi could give you cancer. Most hospitals you can be exposed to upwards of 70 different wifi sources excluding patients and visitors. I've stood in several wards with a wifi analyzer app and seen all the wifi signals (Range of about 30m) that are currently on and I've never seen so many, even standing in the middle of London at Victoria Train Station or St. Pancras you don't get that many.

    Does this research account for that? Because even taking into consideration "The spatial variation of the field strength can be characterized by the well-known Ricean probability distribution, using the Sabine method to evaluate the parameters."

    (Basically imagine a hundred lines coming straight out from your wifi device, put your hand next to it, maybe 20 lines go through your hand, put your hand a meter away and only 1 or 2 lines are now going through your hand.)

    Even accounting for all that... with 70 sources of wifi sending their signals I find the impact of you being a meter away is hardly doing anything... more chance of you disrupting the monitor by throwing your device at it. If a heart monitor is going to be KO'd by a laptop being near it then it'll be ruined whenever the CT scanner downstairs turns on, they kick out a metric ton of EM radiation.

    I do expect there is a degree of 'keep devices away from patients' here due to the fact that if you're looking down tapping away rather than looking at the patient then there is the issue of overlooking things or being distracted.

    MSD is just a distraction that doesn't solve the problem... Oh, sure, the nurse doesn't cause a problem... but what happens when a visitor comes in and his mobile kills the heart monitor? I think the issue is more with the heart monitor... a simple wire cage on the inside of the case should create a Faraday cage that prevents EM radiation from entering.

    Anyway. I expect the technophiles to jump all over this using it as an excuse to complain about computers in wards.

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  • I agree - complete nonsense. Hope the Daily Mail doesn't get hold of this.

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  • Matthew  Carr

    Woops, at the end I said Technophiles rather than Technophobics. No 'edit' button.

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  • Matthew  Carr

    Also... hillarious that related articles are 'Texting during surgery can reduce pain'

    I wonder how they keep MSD in that situation...

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  • The risk to medical equipment was disproved decades ago, when cabling became shielded universally. There's no risk. The main reason for reducing or banning use of wireless devices is simply manners.

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  • Having attended numerous incidents for a well known medical company that manufacturers heart monitors. I can confirm without any reservation that wireless devices do interfere with some heart monitoring devices. The problem is caused by Bluetooth connectivity on wireless devices transmitting on the same frequency band that medical devices use to provide telemetry or wire free functionality. The most common incident is the patient ecg signal is not received by the monitoring device and any patient alarms that would be generated by that signal are subsequently missed. This can result in patient death if the ecg alarm is in the life threatening category.

    Until the UK government allocates a safe frequency band for medical devices to operate in, there will be no safe method to transmit wireless patient data from the patient whilst in the proximity of devices that are also using the same frequency band.

    Most wireless medical devices will work alongside other devices transmitting over the range of WIFI channels without any interference, the problems are normally caused by leaving Bluetooth enabled on devices issued to staff or patients using Bluetooth on their own devices.

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  • Matthew  Carr

    But Bluetooth is unsecure and more or less redundant when hospitals have their own wifi networks.

    Also it points out that things like ECG monitors shouldn't be wireless... The article wasn't dealing with interference but the issue of devices being overloaded by EM radiation, Interference is a different matter one that wifi and bluetooth devices can deal with by having a simple passcode. Unsecured devices are at risk of being hijacked as has happened with a brand of pacemakers in the USA when a security exploit was found that could enable someone to turn them on or off at will.

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  • what about us? we have electrical wiring in all of our cells; each cell is a battery, our nervous system, our Purkinje fibers in our heart, I see NOTHING about safety for staff. staff and patients are both human beings !

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  • The role of medical equipments in hospital, clinics or other health center is very crucial in monitoring, diagnosing and providing treatment to the patient. There are array of medical equipments like present at etc. serve different purpose in medical field. However, it is true that some medical equipments are very sensitive to the wireless devices such as cellular phones, handheld transceivers etc. as they are largest sources of RFI. Thus, these sources must be kept away from such medical equipments to avoid any interference that leads to injuries and death.

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