Real-time filtering technique to remove ECG interference from recorded esophageal EMG

Electromyogram (EMG) is used in various circumstances such as diagnostic and prosthesis control. This paper deals with the diaphragmatic electromyogram (EMGdi) as a controller of mechanical ventilation. However, recorded EMGdi signals are always contaminated by electrocardiogram (ECG). Cancellation of the ECG contamination, especially in real-time, is not a simple operation because the spectra of EMG and ECG overlap. We present in this paper an EMGdi acquisition system implementing an efficient real-time EMG processing technique. This system includes an esophageal catheter and a control unit with Bluetooth link for communication with a user interface. The ECG cancellation part includes two 8-bit microcontrollers communicating via a SPI interface and receiving and sending data via two RS232 serial links and can be easily adapted to be used for any application which needs to eliminate ECG artifacts from EMG. The simulation and experimental results show that the chosen filtering technique gives good results on diaphragmatic EMG and can operate in a hardware system.