Heart rate variability during Pulse Photoplethysmography decreased Amplitude fluctuations and its correlation with apneic episodes

In this study the heart rate variability (HRV) during decreases in the amplitude fluctuations of pulse photople-tysmography signal (PPG) events (DAP) was analyzed for evaluating the possible relations and involvements of the autonomic nervous system, mainly in presence of apneas. The study uses 45 fragments containing a DAP event and being free of artifacts or other physiologic events which were classified as apneic and non-apneic. A HRV signal processing was carried out in order to obtain several time and frequency indexes. The smooth pseudo Wigner-Ville distribution was used for the analysis of HRV. One way ANOVA tests for repeated measures and t-tests were carried out in order to analyze the parameter time evolution and differences between groups. The results show an increase in sympathetic activity during DAP which is deeper for apneic events. Several indexes have shown statistical difference between groups so HRV seems to improve the usefulness of PPG in sleep studies.