For individuals with Down syndrome (DS), obstructive sleep apnea (OSA) is a complex disorder with significant clinical consequences. OSA is seen frequently in DS, and when present, it tends to be more severe. This increased prevalence is likely related to common anatomic abnormalities and a greater risk of additional comorbidities such as hypotonia and obesity. Because signs and symptoms do not often correlate with disease, all children and adults with DS should receive routine screening for OSA. Similar to the general population, polysomnography remains the gold standard for diagnosis. Because individuals with DS may be more susceptible to cardiovascular and neurocognitive sequelae, early diagnosis and treatment of OSA is becoming increasingly important. Treatment options generally involve upper airway surgery (primarily adenotonsillectomy) and continuous positive airway pressure (CPAP); however, various adjunctive therapies including intranasal steroids, palatal expansion, and oropharyngeal exercises are also available. Residual disease status post adenotonsillectomy is common, and further evaluation (eg, drug-induced sleep endoscopy [DISE]) is often needed. More advanced and directed airway surgery can be performed if additional sites of obstruction are observed. Novel therapies including hypoglossal nerve stimulation are emerging as effective treatments for refractory OSA. Due to the diversity among individuals with DS, personalized treatment plans should be developed. Within this arena, opportunities for research remain abundant and should include areas involving patient risk factors, alternative diagnostic methods, and outcome analysis.

Study Objectives: Obstructive sleep apnea (OSA) is common in children with Down syndrome (DS) and associated with significant morbidity. In the current study we examined polysomnographic outcomes of children with DS who underwent tonsillectomy. Methods: A retrospective chart review of children with DS who underwent a tonsillectomy between 2009-2015 was performed. All children had either a concurrent adenoidectomy or had previously underwent an adenoidectomy. Children with preoperative and postoperative polysomnograms within 6 months of surgery were included in the analysis. Preoperative OSA severity was categorized by obstructive apnea-hypopnea index (OAHI) as follows: mild = 1.5-4.9 events/h; moderate = 5-9.9 events/h; severe ≥ 10 events/h. Results: Seventy-five children with DS met inclusion criteria. The cohort included 41 males and 34 females with mean age of 5.1 years (± 3.6 years), range of 0.51-16.60 years. Preoperative OSA severity was as follows, mild = 8/75; moderate = 16/75; severe = 51/75. Cure rates varied depending on definition: 12% for OAHI < 1 event/h and 21% for OAHI < 2 events/h. 48% had residual OAHI < 5 events/h. On postoperative PSG 16/75 saw resolution (OAHI < 2) in OSA; mild = 21/75; moderate = 20/75; severe = 18/75. 48% moderate/severe patients saw conversion to mild or cure. Overall, tonsillectomy resulted in significant improvements in multiple respiratory parameters, including OAHI (OAHI; 21.3 ± 19.7 to 8.0 ± 8.1, P < .001), percent sleep time with oxygen saturations < 90% (19.0 ± 25.0 to 6.1 ± 10.1, P < .001), and percent sleep time with end-tidal carbon dioxide above 50 mmHg (7.7 ± 18.0 to 1.8 ± 6.6, P = .001). Average asleep oxygen saturation was associated with postoperative OSA severity. Conclusions: Children with DS and OSA who undergo tonsillectomy experience improvements in both respiratory event frequency and gas exchange but approximately half still have moderate to severe residual OSA. Keywords: child, Down syndrome, gas exchange, obstructive sleep apnea, polysomnography, tonsillectomy

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Increases in blood flow capacity produced in Gr and Gw by ET appear to be due in part to increased arteriolar density. In contrast, increased arteriolar density does not contribute to increased blood flow capacity of Gw in IST rats.