Inductive interference with implanted medical devices

Thread Starter


Joined Nov 9, 2022
Thank you for reading my post.

I work in a medical lab testing human patients. Some of them have implanted stimulators.

One type of sensor commonly used on patients is circumferential belt Respiratory Inductance Plethysmography. One implanted stimulator manufacturer warns not to use RIP sensors as they are well known to cause interference with the implant. If applied, the physical distance from the circumferential RIP belt to the stimulator implant would be as small as 1 centimeter.

A different device manufacturer is warning their product contains magnets with a strength of "400 mT" which could also affect implanted stimulators:

"Warning: Magnets with a magnetic field strength of 400 mT are used in the mask. With the exception of the devices identified in the contraindication, ensure the mask is kept at least 6 inches (approx. 15.24 cm) away from any other medical implants or medical devices that can be impacted by the magnetic fields to avoid possible effects from localized magnetic fields."

I am not an engineer, just a technician. I am seeking to understand the relative strengths of the magnetic/inductive fields produced by each type of device/sensor and how to measure them on a live patient.

Note, both of these sensor/device items have been FDA approved. Nevertheless, the manufacturers are warning about interference.