Respiratory Signal Extraction from ECG using a Phase-Amplitude Cross-Frequency Coupling Index

Direct measurement of respiration is comparatively rarer than recordings of ECG and EEG for patients under clinical study, especially those in epilepsy monitoring units. We propose a new method for extracting respiration from ECG using phase-amplitude cross-frequency coupling (PAC), which is more resilient to artifacts than existing extraction methods. When analysed with a standard ECG and respiration dataset, PAC performs comparably to ECG envelope extraction, the most commonly employed approach. There was no significant difference between the wavelet phase coherence of this method versus ECG envelope, calculated against actual respiration, nor any significant difference between the distribution of predicted respiration rates. The PAC method's decreased sensitivity to high-amplitude noise suggests it as a candidate for extracting respiration during high-amplitude seizure events when only ECG recordings are available.