Obstructive Sleep Apnoea Syndrome (OSAS) is a common problem in children. The prevalence of OSAS in diagnostic studies ranges widely from 0.1 and 13%, even if great part of the literature converges on variations between 1 and 4%. A difference in the prevalence based on age is not proven, even if several studies indicate a peak of incidence between 2 and 8 years, which is the age in which the tonsils and adenoids are the largest in relation to the underlying airway. OSAS is defined by the American Academy of Pediatrics as ‘‘a disorder of breathing during sleep characterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction (obstructive apnea) that disrupts normal ventilation during sleep and normal sleep patterns”.
Diagnosis of OSAS is based on medical history, physical examination and tests confirming the presence and severity of the upper airway obstruction, it is well known, however, that OSAS in children is not only associated with enlarged tonsils and adenoids, but also with the presence of abnormal airway collapsibility during sleep. The gold standard for diagnosing OSAS is therefore the overnight polysomnography (PSG). Among the parameters measured with PSG, the Apnoea-Hypopnoea Index (AHI) is commonly used to evaluate the presence or absence of disease and to assess its severity; the AHI represents the number of obstructive apnoea and obstructive hypopne as observed per hour of Total Sleep Time (TST).