• Louise M O'Brien and David Gozal.
• Kosair Children's Hospital Research Institute, and Division of Pediatric Sleep Medicine, Department of Pediatrics, University of Louisville, Louisville, KY 40202, USA.
• Sleep. 2005 Jun 1; 28 (6): 747-52.

Study ObjectivesTo measure sympathetic responses in children with and without sleep-disordered breathing.DesignProspective, observational study.SettingKosair Children's Hospital Sleep Medicine and Apnea Center.ParticipantsSubjects 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.InterventionN/A.Measurements And ResultsDuring 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.ResultsThe 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.ConclusionChildren with sleep-disordered breathing have altered autonomic nervous system regulation as evidenced by increased sympathetic vascular reactivity during wakefulness.

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