Sleep-Related Hypoventilation Syndromes

Abstract

During sleep, ventilation in a normal man is generally decreased. The tidal volume and respiratory rate are both reduced compared to wakefulness. Minute ventilation is significantly less in all stages of sleep, particularly in rapid-eye-movement (REM) sleep. Moreover, reduction in upper airway muscle tone during sleep results in increasing upper airway resistance and risk of obstructive sleep apnea. Hypoxic and hypercapnic ventilatory drives also decrease during sleep. As a result, normal adults and children when asleep have a reduction in oxygen saturation and increased carbon dioxide levels. In this chapter we will focus on congenital central alveolar hypoventilation syndrome (CCHS) and obesity hypoventilation syndrome (OHS), which are more commonly found in pediatric practice than the other sleep-related hypoventilation disorders.