Cross-Spectral Analysis of Electrocardiographic and Nostril Airflow Signals Identifies Two Respiratory Frequencies of Heart Rate Modulation

Figure 1

The RRI tachogram (panel (a)), HRV power spectrum (panel (b)), ECG waveform (panel (c)), ECG autospectrum (panel (d)), nostril airflow waveform (panel (e)), nostril airflow autospectrum (panel (f)), the autocorrelation function of ECG (panel (g)), and the cross-spectrum of ECG and nostril airflow (panel (h)) of a representative subject. CCF = cross-correlation function, CSD = cross-spectral density, ms = millisecond, s = second, mv = millivolt, l = liter, and Hz = 1/s.

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