**1. Introduction**

Sleep-related breathing disorders are a group of clinical conditions ranging from habitual snoring to obstructive sleep apnea syndrome (OSAS), frequent in all ages of life. OSAS is a clinical condition still underdiagnosed both in adults and particularly in children, with high cost of care for general population [1, 2]. OSAS can be considered the most severe nocturnal respiratory disorder characterized by repeated episodes of obstructive and/or hypopnea during sleep caused by complete or partial

obstruction of the upper airways. The nocturnal episodes of total or incomplete breathing interruption are identified and recorded in the apnea/hypopnea index per hour (AHI), and the nocturnal oxygen desaturation is expressed as oxygen desaturation index per hour (ODI). In children, in contrast to the adult, definition of OSAS, which requires an AHI ≥ 5 episodes per hour of sleep lasting more than 10 seconds, with persistent thoracoabdominal movements [1], does not require so.

In 1976, OSAS syndrome was identified and described in pediatric age by Guilleminault et al. [3], and from that time on, studies on this pediatric pathology have multiplied, considering its important impact on all aspects of life often linked to the intermittent nocturnal hypoxia not ever associated with the nocturnal respiratory events (hypopneas and apneas).
