Hi all,
Thank you to all who responded to my inquiry about insulin pumps. As always this group proves to be very helpful and informative. Inserted below are most of the responses I received (identifying information removed). The general consensus seems to be to contact the manufacturer to verify, but outside of 5G shouldn't be a problem.
David
David Richardson, Ph.D.
Director, NMR Facility and Cryogenic Services
Office of Research
University of Central Florida
david.richardson_at_ucf.edu<mailto:david.richardson_at_ucf.edu>
407-823-2961
http://sciences.ucf.edu/chemistry/nmr/
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I have a student who has an insulin pump, and he doesn't have a problem. The thing is, it is pump to pump dependent, and you don't know how it might fail. Is it a permanent or detachable pump? Also, do you have an automated sample loader or not?
The student could try and see what happens with the pump. If you have a sample loader it is probably not a problem. If the student is supposed to change probes, it might be.
They can contact the manufacturer and ask (which is the advice I received).
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according to German law, there is a 5 G limit to static magnetic fields for the general population.
I.e., areas with B > 5G must be marked with warning signs.
Form OSH regulations, the exposure limits for people WORKING there (employees, but alss students) are much higher (2 T whole body, 8 T for limbs). This covers almost anything you could do on an NMR magnet (except probably for changing the probe on our unshielded 900 MHz magnet ...).
However, there are exceptions for
- people with passive implants (artificial joints etc.)
- people with active implants (cochlea, pacemaker, insulin pump etc.)
- and pregnant women
For those the stricter rules for the "general population" apply, i.e., the 5 G limit (that's why we ask students doing a practical at our magnets if one of these 3 thingss applies to them).
So, legally you'd have to exclude people with implants from regions with > 5 Gauss. If it's a highly shielded magnet, the person could pass close to the magnet without problems. Whether changing the sample (on top of the magnet) is still safe is questionable (depends a bit on the size of the magnet and how much you have to lean over it to change the sample); tuning the probe by crawling under the magnet most probably is not OK.
Of course 5 G is "nothing" (it's 10 times the Earth magnetic field), most such equipment (e.g. modern pacemakers) easily tolerate up to 1 Tesla without problems.
But as the responsible person (which you probably are for the students) I wouldn't run any risk and ask the person to stay outside of such high field areas.
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The answer depends on whether or not a continuous glucose monitor is also used in conjunction with a pump.
I've worked with mainly older, unshielded magnets. I've been a pump user the entire time I've been around them (~8yrs), but I've only used the continuous glucose monitor the last couple years.
Assuming only a pump (with a non-metal infusion site): remove the pump from the infusion site (all minimed medtronic and disetronic pumps should be removable) and leave outside the 5-gauss line. I routinely wear mine at around 2-Gauss with no apparent problems.
Assuming a continuous glucose monitor: this is more difficult in that the sensors are not intended to be removed. If they are turned off/removed you must recalibrate (which may or may not work) and you can also damage the sensor. I would avoid this. I do routinely wear it at around 2-gauss and so far that doesn't seem to be a problem. For myself, I wear my continuous glucose monitor about 50% of the time and try to run my experiments as much as possible when it's off. When it is on, I get someone else to load the samplesfor me and then tune them (if its a varian instrument that is tuned from below the magnet).
this is the excerpt from the manual for the minimed 670G insulin system:
p32"
Do not expose your pump to MRI equipment, diathermy devices, or other
devices that generate strong magnetic fields (for example, x-ray, CT scan, or
other types of radiation). The strong magnetic fields can cause the devices to
malfunction, and result in serious injury. If your pump is exposed to a strong
magnetic field, discontinue use and cont
act the 24 Hour HelpLine for further
assistance.
Magnetic fields, and direct contact with magnets, may affect the accurate
functioning of your system, which may lead to health risks such as
hypoglycemia or hyperglycemia.
*
Do not expose your transmitter to MRI equipment, diathermy devices, or other
devices that generate strong magnetic fields. Exposure to a strong magnetic
field has not been evaluated and can cause the device to malfunction, result
in serious injury, or be unsafe. If your transmitter is inadvertently exposed to a
strong magnetic field, discontinue use and contact the 24 Hour HelpLine for
further assistance.
*
Do not expose your sensor to MRI equipment, diathermy devices, or other
devices that generate strong magnetic fields as the performance of the sensor
has not been evaluated under those conditions and may be unsafe. If your
sensor is inadvertently exposed to a strong magnetic field, discontinue use
and contact the 24 Hour HelpLine for further assistance.
*
Always remove your pump, sensor, transmitter, and meter before entering a
room that has x-ray, MRI, diathermy,or CT scan equipment. The magnetic
fields and radiation in the immediate vicinity of this equipment can make your
devices nonfunctional or damage the part of the pump that regulates insulin
delivery, possibly resulting in over delivery and severe hypoglycemia.
"
At one point they also mention not using a pump case with a magnetic clip...
This being said, if you nail them down they will admit that none of their warnings are experimentally tested, and they are inclined to be conservative.
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The tolerance of insulin pumps for stray magnetic fields vary considerably, depending on the manufacture materials and vintage of the pump. We have some experience with this and older versions of pumps, from Medtronics at least, seem to easily tolerate much more than 5 Gauss, up to hundreds of Gauss before problems seem to present. Newer versions of their insulin pumps seem to be much more susceptible to compromise in much lower magnetic fields and require that some precautions be taken.
Medtronics used to quote hundreds of Gauss tolerance for their pumps before problems might develop,but they will now not quote any tolerances for their newer models. Their advise and mine is to leave insulin pumps outside of a 5 Gauss line as much as possible and I suggest that users never climb directly under a magnet with the pump active and connected to a person. Medtronics pumps seems to fail with stopped delivery rather than accelerated or excessive delivery, which is good, requiring rewind and reset to continue operation. The best options might seem to be to suspend insulin delivery and remove the pump from users while they are near magnets, especially unshielded magnets, or to test the limits of the normal behavior of the pump for exposure to ,magnetic fields and hope that a persistent failure of the pump does not develop with repeated exposures to magnet fields. I wish you and them well.
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I think 5 Gauss should be safe. It is indeed typically about just an inch or so outside the magnet. You might encounter some higher fields right under the magnet.
So depending on where the pump is a probe change might expose it to slightly higher fields. You will have an area of 5 Gauss or higher right under the magnet.
So I would say normal operation of the spectrometer including sample changes ok, but I would recommend to stay away from probe changes.
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I advise users to take off the pump when they are in the 5G line. One of my TAs was diabetic and would remove his pump to fill nitrogen and helium. I have a current user, who doesn't remove her pump, but she's in the 5G line for 2 minutes at a time.
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I have a student here who uses his belt-mounted insulin pump around unshielded 500-MHz NMR magnets all the time without incident. His has a graph on it, and he can tell whether a magnet trip has influenced his glucose profile, and he says it never has. He knows that if the device malfunctions, it sends him a message and shuts off. He can then intervene manually, and he has never had that happen.
One person's story does not necessarily pertain to your situation, but I find our situation with this student an optimistic one.
Manufacturers of insulin pumps will probably have nothing to say about having their devices around magnetic fields, except to not wear the inside MRI units. Legal liability intruding on common sense.
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My husband has had an insulin pump for 15 years - he removes it and either leaves it in his office or places it on the computer desk outside the 5G line. It's fine to take it into the magnet room, just not inside the 5G radius.
Received on Thu Mar 07 2019 - 10:14:52 MST