Autonomic dysfunction in children with sleep-disordered breathing

STUDY OBJECTIVES: To measure sympathetic responses in children with and without sleep-disordered breathing. DESIGN: Prospective, observational study. SETTING: Kosair Children's Hospital Sleep Medicine and Apnea Center. PARTICIPANTS: Subjects were prospectively recruited from children undergoing overnight polysomnographic assessments and were retrospectively grouped according to the results of the polysomnogram. Sleep-disordered breathing was defined as an apnea-hypopnea index >5 and children were assigned to the control group if their apnea-hypopnea index was < 1. INTERVENTION: N/A. MEASUREMENTS AND RESULTS: During quiet wakefulness, pulse arterial tonometry was used to assess changes in sympathetic activity following vital capacity sighs in 28 children with sleep-disordered breathing and 29 controls. Each child underwent a series of 3 sighs, and the average maximal pulse arterial tonometry signal attenuation was calculated. Further, a cold pressor test was conducted in a subset of 14 children with sleep-disordered breathing and 14 controls. The left hand was immersed in ice cold water for 30 seconds while right-hand pulse arterial tonometry signal was continuously monitored during immersion and 20-minute recovery periods. Signal amplitude changes were expressed as percentage change from corresponding baseline. Results: The magnitude of sympathetic discharge-induced attenuation of pulse arterial tonometry signal was significantly increased in children with sleep-disordered breathing during sigh maneuvers (74.1% +/- 10.7% change compared with 59.2% +/- 13.2% change in controls; P<.0001) and the cold pressor test (83.5% +/- 7.3% change compared with 74.1% +/- 11.4% change in controls; P=.039). Further, recovery kinetics in control children were faster than those of children with sleep-disordered breathing. CONCLUSION: Children with sleep-disordered breathing have altered autonomic nervous system regulation as evidenced by increased sympathetic vascular reactivity during wakefulness.