The Dynamic Pneumocardiogram: An Application of Coherent Signal Processing to Cardiovascular Measurement

The modulation of respiratory flow by cardiac function has been the subject of scientific investigation for over 100 years. The waveform of these modulations is called a pneumocardiogram (PNCG). All reported pneumocardiograms have been obtained during a state of apnea with a patent glottis maintained by voluntary control or intratracheal intubation. In this study, simple filters and coherent signal averaging techniques were applied to extract PNCG's from unrestrained breathing patterns in man. Interpretable PNCG's were easily collected by this method under varied conditions including sitting at rest, running in place, and resting supine. The PNCG's observed in this study were unique to each individual and were altered by measurement conditions. The application of these techniques to other cardiovascular measurements including phonocardiograms, arterial pulses, impedence plethysmograms, etc., is discussed.