A comparison between the peak ear pulse derivative and the R-R interval variabilities

The power spectral analysis of the beat to beat variations in parameters related to the ventricular performance may provide information concerning the autonomic control of the mechanical function of the heart. The peak of the first derivative of the ear densitogram (PD) has been used as a noninvasive index to evaluate the left ventricular function. The aim of the authors´ study was to examine the beat to beat variations in the PD of 5 subjects during a sequence of maneuvers that cause a different degree of autonomic modulation. Power spectral comparisons among the PD variability, the R-R variability and the respiratory amplitude suggest that the PD has periodical short term fluctuations which are partially explained by autonomic mechanisms