Performance of ventilators compatible with magnetic resonance imaging: A bench study

Abstract

BACKGROUND: Magnetic resonance imaging (MRI) is indispensable for diagnosing brain and spinal cord abnormalities. Magnetic components cannot be used during MRI procedures; therefore, patient support equipment must use MRI-compatible materials. However, little is known of the performance of MRI-compatible ventilators. METHODS: At commonly used settings, we tested the delivered tidal volume (VT), FIO2, PEEP, and operation of the high-inspiratory-pressure-relief valves of 4 portable MRI-compatible ventilators (Pneupac VR1, ParaPAC 200DMRI, CAREvent MRI, iVent201) and one ICU ventilator (Servo-i). Each ventilator was set in volume control/ continuous mandatory ventilation mode. Breathing frequency and VT were tested at 10 breaths/min and 300, 500, and 700 mL, respectively. The Pneupac VR1 has fixed VT and frequency combinations, so it was tested at VT = 300 mL and 20 breaths/min, VT = 500 mL and 12 breaths/min, and VT = 800 mL and 10 breaths/min. FIO2 was 0.6 and 1.0. At the air-mix setting, FIO2 was fixed at 0.5 with the Pneupac VR1, 0.45 with the ParaPAC 200DMRI, and 0.6 with the CAREvent MRI. PEEP was set at 5 and 10 cm H2O, and pressure relief was set at 30 and 40 cm H2O. RESULTS: VT error varied widely among ventilators (-28.1 to 25.5%). As VT increased, error decreased with the Pneupac VR1, ParaPAC 200DMRI, and CAREvent MRI (P < .05). FIO2 error ranged from -13.3 to 25.3% at 0.6 (or air mix). PEEP error varied among ventilators (-29.2 to 42.5%). Only the Servo-i maintained VT, FIO2, and PEEP at set levels. The pressure-relief valves worked in all ventilators. CONCLUSIONS: None of the MRI-compatible ventilators maintained VT, FIO2, and PEEP at set levels. Vital signs of patients with unstable respiratory mechanics should be monitored during transport and MRI.