Background: Patients with obstructive sleep apnea (OSA) are characterized by deranged cardiovascular variability, a well-established marker of cardiovascular risk. While long-term treatment with continuous positive airway pressure leads to a significant improvement of cardiovascular variability, little is known of the possibility of achieving the same results with other therapeutic approaches. The aim of our study was to investigate the responses of autonomic indexes of neural cardiac control to another type of OSA treatment based on an oral jaw-positioning appliance.
Methods: In 10 otherwise healthy subjects with OSA (OSA+) and in 10 subjects without OSA (OSA-) we measured heart rate, BP, and indices of autonomic cardiac regulation derived from time-domain and spectral analysis of R-R interval (RRI), before and after 3 months of treatment with the oral device. High-frequency (HF) power of RRI was taken as an index of parasympathetic cardiac modulation, and the ratio between low-frequency (LF) and HF RRI powers as an indirect marker of the balance between sympathetic and parasympathetic cardiac modulation.
Results: At baseline, in comparison with OSA- subjects, OSA+ subjects displayed a significantly lower RRI variance (p < 0.02) and reduced HF RRI powers (p < 0.001). After 3 months of treatment with the oral device, the OSA+ group showed a marked reduction in apnea-hypopnea index (p < 0.001), a lengthening in RRI and a significant increase in its variance (p < 0,02), an increased HF RRI power (from 134 +/- 26 to 502 +/- 48 ms2, p < 0.001), and a reduction in LF/HF RRI power ratio (from 3.11 +/- 0.8 to 1.5 +/- 0.5). As a result of these changes, after the 3-month treatment there were no more significant differences between the two groups in these parameters. In both OSA+ and OSA- groups, body weight, heart rate, and BP did not change over time.
Conclusions: Three months of treatment with a specific oral jaw-positioning appliance improves cardiac autonomic modulation in otherwise healthy patients with OSA of mild degree.