Wireless electrocardiogram transmission: Overcoming the technical barriers

Abstract

Study objectives: Wireless ECG transmission relies on cellular network development and network transmission priority. During our study of the effect wireless ECGs have on acute coronary syndrome management, we encountered difficulty with a low first-transmission success rate. We then switched the type of cellular network in an effort to improve wireless transmission rates. Our objective is to improve the rate of successful first transmission of wireless ECGs. Methods: The initial network was a General Packet Radio Services (GPRS) network, which transmits the ECG on a packet data network. On this network, data were given a lower priority than voice transmissions. The network was then switched to a Global System for Mobile Communications (GSM) network, which enabled ECGs to be transmitted with the same priority as voice information. Although the GPRS network is actually the more advanced network, the GSM network was more mature in terms of network development. Geographically, the transmission area spanned more than 2 small cities located in a valley and the surrounding towns. All the ECGs transmitted during this phase were used to test the system. ECGs were transmitted from the field by paramedics who had been trained to use the system. Some of the transmissions were chest pain patients, some were non–chest pain patients, and some were simply test transmissions. We recorded data on transmissions from August 17, 2003, to October 26, 2003. A successful first transmission occurred if the paramedic turned on the unit and on the first attempt was able to connect to the base station at the hospital and transmit data. "Retransmission" success occurred if the paramedics could successfully transmit any time after the first attempt, including during transport and after hospital arrival. Transmission status was considered "unknown" if the paramedic name was transmitted and we were unable to verify a successful or unsuccessful transmission, which happened in part because of the machine's automatic transmit feature, which is designed to transmit when the unit is activated, even when not being tested and logged by the paramedic. First transmission success rates and overall transmission success rates were compared with a χ 2 test of association. Results: Before switching networks, the first transmission success rate was 34.4% (N=17 out of total N=48). Adding in the retransmission successes (N=21) led to an overall success rate of 79.1% (N=38 out of total N=48). There were 2 unsuccessful transmissions (4.2%) and 8 unknown transmissions (16.7%). After the network switch, the first transmission success rate increased to 67.9% (N=36 out of total N=53). Adding in the retransmission successes (N=4) led to an overall success rate of 75.5% (N=40 out of total N=53). There were no documented unsuccessful transmissions and 13 unknown transmissions (24.5%). The difference in first transmission success rates was significant (χ 2 =10.67, P =.001), and there was no difference detected in overall transmission success rate between the 2 groups (χ 2 =0.196, P =.658). Conclusion: Wireless ECG transmission rates can be affected by the type and maturity of the cellular network. We found a higher first-transmission success rate by switching to a more mature network with equal voice and data transmission priority.