Purpose: Magnetic Resonance Imaging (MRI) is a valuable diagnostic tool
for neuroimaging in the Emergency and Critical Care setting, but its use may
be limited in acutely and chronically ventilated patients, who cannot maintain
the supine position in spontaneous breathing for the duration required for the
procedure, as it may be the case in acute and chronic neurological and neuromuscular
diseases with diaphragm involvement.
We aimed to evaluate the performance of home life support ventilators used
with a longer circuit, allowing the application of ventilatory support during MRI.
The study hypothesis was that home ventilators are accurate in delivery the set
ventilatory parameters despite a modified circuit.
Materials and Methods: Four non-MRI-compatible life-support home
ventilators were tested on a bench using 3 circuits of 4.8 m length and 3
ventilation settings.
Results: We found measurable differences in the efficacy of the ventilation
delivered to the test lung, which was influenced from the used ventilator, the type
of circuit and the ventilation parameters. In the volumetric setting with unvented
circuit, the difference between set VT and delivered VT ranged between -10%
and +3%. In the barometric setting, only the ventilators providing automatic
compensation for circuit compliance and resistance were reliable in the delivery
of the set inspiratory and end-expiratory pressures.
Conclusion: The use of home ventilators during MRI may represent a
valuable alternative when a MRI-compatible ventilator is not available, but may
require an adjustment of the ventilatory setting, and a systematic verification of
the parameters effectively delivered to the patient.