Cardiorespiratory changes as they relate to sleep in transition from pediatric to adulthood

Sleep and the cardiorespiratory system affect each other. This chapter focuses on some aspects of the cardiorespiratory system and their influence on sleep, and some which are affected by sleep, highlighting age-dependent changes in these relationships. The characteristics of the upper airway (UAW) (anatomy and physiology) and their impact on the individual's susceptibility to have sleep-disordered breathing are described in light of changes from childhood to adulthood. In addition, arousability (cortical/autonomic) and arousal thresholds, which also affect sleep disordered breathing (SDB), and vascular endothelial function which may be affected by SDB, are discussed, with respect to age. Age-dependent cardiorespiratory changes may affect the phenotype of obstructive sleep apnea (OSA). In children, the most common anatomical risk factors are hypertrophic tonsils and/or adenoids, while in adults, it is obesity. Airway length, which may also alter collapsibility, increases with age. In children, upper airway (UAW) is shorter and is similar between genders, whereas in adolescents and adults, it becomes longer especially in males. UAW dilator muscles respond to negative pressure during wakefulness similarly in children and adults, although it appears that the UAW is more stable in children, who are less likely to collapse than adults. Their collapsing pressure Pclose/Pcrit is more negative than in adults. Transient arousals from sleep, which reestablish the airway patency and ventilation after SDB events, are more likely to occur in adults than in children, in whom frequently there is only autonomic response without a cortical arousal. This may lead to long duration of hypoventilation with hypercapnia seen in children but not in adults. Both children and adults tend to develop endothelial dysfunction (ED) as a complication of OSA, but in children it is more likely to be reversible with treatment, perhaps due to the shorter duration of disease prior to treatment. These age-related changes are reviewed and discussed.