Objective To test the hypothesis that levels of adropin, a recently discovered peptide that displays important metabolic and cardiovascular functions, are lower in obstructive sleep apnea (OSA), especially when associated with endothelial dysfunction. Study design Age-, sex- and ethnicity-matched children (mean age: 7.2±1.4 years) were included into one of three groups based on the presence of OSA in an overnight sleep study, and on the time to post-occlusive maximal reperfusion (Tmax>45 sec) with a modified hyperemic test. Plasma adropin levels were assayed using a commercial ELISA kit. Results Among controls, mean morning adropin levels were 7.4 ng/ml (95% confidence intervals: 5.2–16.3 ng/ml) OSA children with abnormal endothelial function (OSA+/EF+) had significantly lower adropin levels (2.7±1.1 ng/ml, n=35) compared with matched controls (7.6±1.4 ng/ml; n=35; p<0.001), and to children with OSA and normal endothelial function (OSA+/EF−: 5.8±1.5 ng/ml, n=47; p<0.001). Plasma adropin <4.2 ng/ml reliably predicted endothelial functional status, but individual adropin levels were not significantly correlated with age, BMI-z score, obstructive apnea-hypopnea index (AHI) or nadir SpO2. Adropin levels were assessed after adenotonsillectomy in a subset of children with OSA (n=22), and showed increases in OSA+/EF+ (2.5±1.4 ng/ml to 6.4±1.9 ng/ml, n=14; p<0.01) but remained unchanged in OSA+EF− (5.7±1.3 ng/ml to 6.4±1.1 ng/ml, n=8; p>0.05). Conclusion Plasma adropin levels are reduced in pediatric OSA when endothelial dysfunction is present, and return to within normal values after adenotonsillectomy. Assessment of adropin circulating levels may provide a reliable indicator of vascular injury in the context of OSA on children.

Study Objectives: Adenotonsillectomy (AT) is the treatment of choice for obstructive sleep apnea (OSA) in children with adenotonsillar hypertrophy. Severe OSA, identified by the apnea-hypopnea index (AHI), is a risk factor for surgical complications and AHI thresholds are used by surgeons to decide elective postoperative hospital admissions. The objective of this study was to identify the prevalence of surgical complications of AT in children with severe OSA and determine their association with specific parameters of polysomnography (PSG). Methods: Retrospective evaluation of respiratory and nonrespiratory complications in children undergoing AT for severe OSA was performed. Events were then compared to several individual PSG indices. PSG indices included classic parameters such as AHI, and obstructive apnea indexes (OAI) as well as gas exchange parameters including the oxygen desaturation index (ODI), lowest oxyhemoglobin saturation (lowest SpO 2 ), peak end-tidal CO 2 (peak ETCO 2 ), the percentage of the total sleep time (%TST) with ETCO 2 > 50 mmHg (%TST ETCO 2 > 50 mmHg) and oxygen saturation < 90% (%TST O 2 < 90%). Results: A total of 158 children were identified with severe OSA. Major respiratory complications occurred in 21.5% and were only associated with the ODI (P =.014), lowest SpO 2 (P =.001) and %TST O 2 < 90% (P <.001). Minor respiratory complications occurred in 19.6% and these were not associated with any PSG parameters. Major nonrespiratory complications occurred in 4.4% and also were not associated with any PSG parameters; however, minor nonrespiratory complications occurring in 37.3%, and were associated with %TST O 2 < 90% (P < 0.001). Conclusions: PSG measures of gas exchange are strongly associated with postoperative complications of AT and are better suited for postoperative planning than classic indices such as AHI.

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