Different effects of CPAP and APAP therapies on the autonomic nervous system in osa patients

Obstructive sleep apnea (OSA) is a common sleep disorder which causes the reduction of the upper airways muscular tone collapsing the same. This disorder is associated with bad sleep quality leading to excessive daytime sleepiness and increased risk of cardiovascular diseases. The main therapies are the continuous positive airways pressure (CPAP) and auto-CPAP which are devices that force a positive pressure in the upper airways in different manner. The aim of this work was to evaluate the different response of the cardiovascular autonomic nervous system to the therapies. We applied mono and bivariate autoregressive time invariant spectral estimation methods to the heart rate variability and respiratory signals coming from polisomnography executed on 12 patients: 4 during APAP, 4 during CPAP and 4 in basal condition as group of control. We principally found significant differences between groups in HRV variance, low-to-high frequencies ratio (LF/HF) and different coherence levels between signals. These preliminary results seem to suggest different effects of the therapies, with a greater sympathetic activation for APAP group and a better efficacy of CPAP in bringing back pathological condition closer to normality