Introduction
Down syndrome (DS) is one of the most common birth defects in the United States with approximately 6000 births annually, resulting in an estimated birth prevalence of 14 per 10,000 live births.(Parker et al. 2010) Infant with DS (I-DS) are at a high risk of congenital morbidity including congenital heart disease, gastrointestinal disorders, and metabolic abnormalities(Benhaourech et al. 2016; Miller and Cosgriff 1983; Stoll et al. 2015) frequently requiring intensive care unit admission.(Martin et al. 2018; Seither et al. 2021; So et al. 2007)
Sleep disordered breathing (SDB) is a common comorbidity imposing additional burden on I-DS.(Lee et al. 2018) Unique craniofacial features of DS, macroglossia, and shortened palate and midface hypoplasia along with generalized hypotonia make I-DS highly susceptible to OSA.(Maris et al. 2014) Additionally, these patients are at risk for hypoxemia and hypoventilation due to coexisting conditions such as congenital heart disease, smaller lung volumes and hypotonia.(Fan et al. 2017; Wong and Rosen 2017) Cardiovascular and neurocognitive consequence of longstanding and untreated childhood SDB(Capdevila et al. 2008; Greene and Carroll 1997) can be even more detrimental in children with DS. In particular, the risk of pulmonary hypertension and cor-pulmonale in children with DS(Breslin et al. 2014) can be markedly increased in the presence of SDB. Moreover, impaired sleep quality affects daytime function, behavior and quality of life.(Bassell et al. 2015) Therefore, screening for SDB in its entirety (i.e., beyond OSA) is important in early childhood. The American Academy of Pediatrics (AAP)’s published anticipatory guidelines for children with DS recommends that a discussion be held with the parents at least once during the first 6 months of life to screen for symptoms suggestive of OSA; snoring, witnessing breathing pauses, heavy breathing, uncommon sleep positions, frequent nocturnal awakening, daytime symptoms and/or behavioral concerns that could be associated with poor sleep.(Bull 2011) The AAP also recommends referral to a sleep physician for further examination and evaluation of a possible OSA if any of the symptoms occur. Despite these recommendations, I-DS are not commonly referred for SDB evaluation. The AAP recommends assessing for symptoms of OSA, and recommends referral to a pediatric sleep laboratory for polysomnography (PSG) by 4 years of age for all children with DS due to poor correlation between parent report and PSG results but suggests it to be performed after the first year of life,.(Bull 2011)  By age 4 years old a child with OSA may already have negative outcomes or comorbidities associated with untreated hypoxemia or hypoventilation. Despite the clinical implication of SDB in early age, studies exclusively examining infants with DS are rare. In this study we aimed to assess the prevalence of OSA, central sleep apnea (CSA), sleep hypoxemia and sleep hypoventilation, and the impact of adenotonsillectomy (AT) on SDB in I-DS.