Conducted EMC testing reveals malfunctions in automated external defibrillators with patient leads connected

Previously we performed radiated electro-magnetic compatibility tests of automated external defibrillators (AEDs) for radiated immunity per the IEC 60601-1-2 and ANSI/AAMI/IEC 60601-2-4 standards, in the prescribed 80-2500 MHz radiofrequency range, with the patient leads connected. We observed malfunctions for several AEDs in the 30 to 45 MHz range. Our present study involves conducted (injected current) testing from 10 to 80 MHz using prescribed IEC methods. We now tested the same AEDs plus one. We injected 3 Vrms on the patient leads from 10 MHz-80 MHz and 6 Vrms at Industrial Scientific and Medical frequencies in this range. Ventricular fibrillation (V-Fib) signals and normal sinus rhythm (NSR) signals were delivered to the patient leads from an AED tester. We also performed radiated testing in the 70-90 MHz band with 10V/m and 20V/m to compare with conducted testing. For conducted tests three AEDs gave false diagnoses (failed to identify V-Fib signals) at some frequencies. For the radiated testing, only one AED gave a false diagnosis. Two of these AEDs are no longer produced but are still in use. Discrepancies between the radiated and conducted test results are due to basic differences in the test methods and mechanisms of interaction.