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Modification of a critical care ventilator for use during magnetic resonance imaging
Sherwin E Morgan1, John J Kestner, Jesse B Hall
1Department of Respiratory Therapy, The University of Chicago Hospitals, 5841 S Maryland Avenue, MC0981, Chicago IL 60637, USA. smorgan@uchospitals.edu
Introduction:
The unique electromagnetic environment of the magnetic resonance imaging (MRI) scanner presents particular problems for critically ill patients requiring mechanical ventilation during MRI. Most currently available MRI-compatible ventilators are limited in scope and function and thus may not be suitable for patients requiring high peak inspiratory pressure or flow.
Methods:
To determine whether a standard critical care ventilator could be used under MRI conditions, we modified a Siemens Servo 900C by replacing the standard oxygen blender with an MRI-compatible blender. We then calibrated the ventilator and tested it on a mechanical lung during active MRI scanning at magnetic fields up to 1.5 tesla. After verifying adequate function, we used the ventilator to support 21 critically ill patients requiring mechanical ventilation during MRI.
Results:
In all cases we found no alterations in ventilator performance resulting from the electromagnetic interference typical of an MRI scan. We also found no abnormalities in the alarm systems for fraction of inspired oxygen, high inspiratory pressure, or minute volume. Finally, we found no degradation of MRI image quality resulting from ventilator operation during test scanning.
Conclusions:
We conclude that with minor modifications the Siemens 900C ventilator can safely ventilate critically ill patients during MRI.