Experimental comparison of different bandaging techniques for prevention of magnet displacement in cochlear implant patients

Introduction:

Magnetic resonance imaging in (MRI) cochlear implant (CI) patients demands special considerations to prevent magnet displacement which can lead to complications such as infections or skin necrosis. An essential precaution is applying a pressure bandage (PB) on the magnet. The aim of this study was to compare different bandaging techniques regarding the maximum force which they can withstand before the magnet is displaced.

Material and methods:

A CI512 dummy (Cochlear Ltd, Australia) was fixed on an artificial head in such a way, that the magnet could be pressed out of it's encasing from the inside of the head using a lifting table (ZOLIX INSTRUMENTS, China). The force necessary to displace the magnet was recorded with a load cell (ME-Messsysteme GmbH, Germany).

Results:

We compared a cohesive bandage with and without a plastic counter-pressure piece as well as the bandaging system from Cochlear ltd (Sydney, Australia). When using the counter pressure piece 33,5 ± 6,1N instead of 11 ± 3,0N were necessary to create a magnetic dislocation. Using the cochlear system with an indicator bandage and a credit card shaped plastic piece lead to a further improvement of 56,8 ± 3,5N.

Discussion:

When applying a pressure dressing prior an MRI scan we strongly recommend the use of a counter pressure piece. Also, the use of an indicator bandage helped reproducing the bandaging pressure more likely with a lower relative scatter of the measured forces (6% scatter of the mean instead of 27% or 18% respectively). This bandaging technique in combination with a credit card shaped counter pressure piece is recommended.

Publication History

Publication Date:
23 April 2019 (online)