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J Clin Monit Comput (2012) 26:157161 DOI 10.1007/s10877-012-9346-0
Intraoperative MRI electrical noise and monitor ECG lters affect arrhythmia detection and identication
Melissa Bailey Gwynne Kirchen Bridget Bonaventura
Kelly Rosborough Mahmoud Abdel-Rasoul
Roger Dzwonczyk
Received: 3 March 2011 / Accepted: 20 February 2012 / Published online: 3 March 2012 Springer Science+Business Media, LLC 2012
Abstract Most electrical equipment in the modern operating room (OR) radiates electrical noise (EN) that can interfere with patient monitors. We have described the EN that an intraoperative magnetic resonance imaging (iMRI) system emits and have shown that this high-energy EN diminishes the quality of the ECG waveform during iMRI scans in our neurosurgical OR. We have also shown that the ECG signal lters in our iMRI-compatible patient monitor reduce this interference but, in the process, disturb the true morphology of the displayed waveform. This simulation study evaluates how iMRI-generated EN affects the ability of the anesthetist to detect and identify ECG arrhythmias and whether the patient monitors ECG signal lters can improve arrhythmia recognition. Using an ECG
simulator, we generated Lead II and V5 ECG signal segments that contained either no arrhythmia or one of four common cardiac arrhythmias. We ltered the ECG segments with four lters available on our iMRI-compatible monitor (Veris MR, MEDRAD Inc., Indianola, PA USA). We then digitized the segments and mixed simulated iMRI EN into the resultant tracings. With institutional approval and written informed consent, board-certied anesthesiologists reviewed the tracings, determined if an arrhythmia was present and identied the arrhythmia. We conducted the study anonymously. We reported the data as percent correct arrhythmia detection and correct arrhythmia identication. Thirty-one anesthesiologists completed the study. Overall, the participants correctly detected 79.5% (95% CI: 77.2,81.7%) of the arrhythmias and correctly identied 62.5% (95% CI: 59.8, 65.3%) of the arrhythmias, regardless of EN presence. Although the proportions among monitor noise lters studied were not signicant, the manufacturer-designated MR5 Veris MR lter optimized arrhythmia detection and arrhythmia identication for our participants, regardless if EN was present in the ECG tracings. In the neurosurgical OR, the anesthetist must be able to effectively monitor a patient in the presence of iMRI-generated EN. Depending on the OR design, the patient may be out of the anesthetists direct view during a scan procedure. The...