Clinical testing of cellular phone ringing interference with automated external defibrillators

This study examined cellular phone ringing interference with automated external defibrillators (AED). The phone systems tested were two single band handheld telephones: (1) a Global System for Mobile Communication (GSM) receiver; and (2) a Personal Communication Services (PCS) receiver. The ringing phase of a digital cellular phone includes a brief burst of peak-emitted power. The GSM had a maximum power output of 2 W, operating on a 900 MHz carrier frequency, and the PCS had a maximum output of 1 W, operating on a 1800 MHz carrier frequency. During AED monitoring, the digital cellular telephone was placed successively in three positions: (1) on the AED; (2) on the patient's chest between the electrodes; and (3) on the connector between the electrodes and the AED cable. After positioning the cellular phone, calls were placed during the AED analyzing phase. Three AED models were tested using their original electrodes: (1) LifePak 20 monitor/defibrillator device; (2) Lifepak 20 P monitor/defibrillator/stimulator (Medtronic Emergency Response Systems, Redmond, WA, USA); and (3) HeartStart XL M4735A monitor/defibrillator (Philips Medical Systems, Andover, MA, USA). The first two devices had Quik-Combo™ electrodes and the third device had Adults Plus multifunction electrodes. Ninety-one tests were performed on 13 patients. The only disturbance provoked by testing was noise emitted by the AED speaker when the receiver was close to the device. The noise began 2–4 s before the first audible ringing tone and persisted throughout the ringing phase. The distance at which this effect could be prevented was 15 cm. Clinical testing during ECG monitoring by an AED during call from a cellular phone did not show any analysis dysfunction during unshockable rhythms and provoked only transient dysfunction of the speaker device.