Radiofrequency susceptibility tests on medical equipment

The most recent problems of electromagnetic interference (EMI) with medical equipment arise from the widespread use of portable cellular phones and two-way radios in critical care areas of hospitals. The Medical Devices Bureau has studied the effects of radiated electric fields on eight different types of monitoring and therapeutic medical equipment over the frequency range of 1 MHz-2000 MHz. The test protocol was based on the IEC standard 801-3 (1984). Seven of the eight devices tested did not meet the requirements of Severity Level 3 of IEC standard 801-3 (immunity to fields of 10 V/m). Six of the eight failed to meet Severity Level 2 (immunity to 3 V/m) as prescribed by IEC standard 601-1-2 for medical electrical equipment. These preliminary findings indicate that care should be taken when operating VHF radios, UHF radios and cellular phones within one meter of these devices.