Autonomic Function in Adults with Obstructive Sleep Apnea

Background: Obstructive Sleep Apnea (OSA) is the most prevalent form of sleep disordered breathing and could become an important public health issue in India. Patients with OSA have high levels of sympathetic nerve activity during sleep. The autonomic alterations persist during wakefulness and are considered to contribute to the cardiovascular disorders associated with OSA. Aims & Objective: The aim of the present study was to study autonomic function in adults with Obstructive Sleep Apnea using autonomic cardiovascular tests. Material and Methods: 30 normal controls (Group I) and 30 patients with Obstructive Sleep Apnea (Group II) of both sexes in the age group of 35-45 years were subjected to a battery of autonomic function tests. The heart rate response to standing (30:15 ratio), heart rate response to deep breathing (E:I ratio), and the Valsalva ratio were used to assess parasympathetic function while the isometric handgrip exercise and cold pressor tests were used to assess sympathetic function. Statistical analysis was done using SPSS 17 and unpaired student t test. Results: The 30:15 ratio, E:I ratio and Valsalva Ratio were significantly lower (p value < 0.001) in the patients with OSA when compared to the controls, while the diastolic pressure difference in the isometric hand-grip exercise test and the cold pressor tests were significantly higher (p value < 0.001) in the patients with OSA. Conclusion: Our study revealed that there was sympatho-vagal imbalance in adult patients with Obstructive Sleep Apnea, with decreased parasympathetic and increased sympathetic activity. Key-Words: Autonomic Cardiovascular Tests; Autonomic Function; Obstructive Sleep Apnea (OSA)