O163 Autonomic nervous system dysfunction in patients with high obstructive sleep apnea risk

Abstract

Objectives The aim of this study was to compare autonomic nervous system (ANS) function in subjects with high OSA (obstructive sleep apnea) risk versus subjects with low OSA risk. Methods Out of 47 consecutive subjects enrolled (22 females, mean age 48.23 ± 16.09 years), 27 had high OSA risk and 20 had low OSA risk according to the Berlin Questionnaire (BQ). They all underwent standardized battery of ANS testing, including blood pressure and heart rate response to Valsalva maneuver, deep breathing test and head up tilt table test. Respiratory sinus arrhythmia (RSA), Valsalva ratio (VR) were determined and cardiovagal score of the Composite Autonomic Scoring Scale (CASS) was determined. Adrenergic score was calculated from the blood pressure response during Valslava maneuver and tilt table test. Finally heart rate variability (HRV) was determined in supine and standing positions. Results High OSA risk subjects had lower RSA compared to low OSA risk subjects (9.96 ± 5.45 vs. 15.17 ± 8.94, p = 0.022). Also VR was lower in subject with high OSA risk versus low OSA risk subjects (1.55 ± 0.34 vs. 1.83 ± 0.41, p = 0.024). There where no significant differences in CASS adrenergic score and HRV between groups. Discussion Pathogenesis of ANS dysfunction in OSA is not elucidated. Sympathetic hyperactivity leads to hypertension but can hardly explain higher cardiac morbidity and mortality. Further research is warranted to investigate the role of vagal down regulation in OSA pathogenesis. Conclusion High OSA risk is associated with vagal down regulation. Significance These findings confirms presence of vagal down regulation which might reflect central nervous system damage in OSA and also might contribute to cardiac morbidity and mortality.