Towards a smart phone-based cardiac monitoring device using electrical impedance tomography

A novel framework for cardiac monitoring is presented that leverages a custom smart phone application and a wearable electrical impedance tomography (EIT) system. The smart phone application required to implement this framework has been designed and is described here. This technology could greatly improve telemonitoring of patients with chronic heart failure. A simulated portable EIT device was constructed that wirelessly sends data to the smart phone. The developed application receives wireless data transmission, performs EIT image reconstruction, and extracts a post-processing measure correlated to cardiac output. Data transmission rates of 4.2 MB/s were achieved between a simulated EIT system (server) and phone (client). Image reconstruction and post-processing implemented on a smart phone requires 332 ms, moderately longer than the 109 ms required on a modern laptop based implementation. The 332 ms is well within the approximately one second processing time needed to measure beat-to-beat cardiac output (i.e. assuming a 60 bpm heart rate).