Sleep related breathing disorders in adults with Down syndrome.

BACKGROUND: While the prevalence of obstructive sleep apnoea syndrome among children with Down syndrome is reported to vary from 30 to 50%, the nocturnal respiratory patterns of adults with Down syndrome is not well known. OBJECTIVES: The aim of this study is to evaluate sleep-related breathing disorders in a sample of adults with Down syndrome. METHODS: We studied the nocturnal respiratory patterns of 6 adults with Down syndrome, aged 28-53 years. All participants were monitored for 8 hours using a 12 channel polysomnograph. Respiratory events (apnoeic and hypopnoeic) were classified as obstructive or central, in relation to the presence or the absence of paradoxical breathing. RESULTS: All participants had respiratory pauses during sleep. 5 of them had an apnoea/hypopnoea index > 10, justifying the diagnosis of sleep apnoea syndrome. About 85% of the respiratory events were apnoeic, the others being hypopnoeic. Among all the respiratory events 89.2% were obstructive, whereas only 10.8% were central. The central events were almost always organised in very low and regular sequences and respiration frequently showed a true periodic pattern, consisting of short periods of augmented breath followed by central events causing oxygen desaturation. CONCLUSIONS: According to the literature and in conjunction with the current study's results it could be hypothesised that the nocturnal respiratory pattern of adults with Down syndrome depends on several pathogenetic factors such as age, severity of upper airway abnormalities, body mass index (BMI), other pathological conditions and age-related brainstem dysfunction.

Hypercapnia in overlap syndrome: possible determinant factors.

We retrospectively evaluated data from 213 consecutive patients; 152 were affected by obstructive sleep apnea (OSA), 29 had OSA associated with chronic obstructive pulmonary disease (COPD), also known as overlap syndrome, and 32 had COPD. Patients with obesity-hypoventilation syndrome were not included. The aims of the study were to evaluate the anthropometric, pulmonary, and polysomnographic characteristics of patients affected by overlap syndrome compared to "simple" OSA and to COPD subjects and to analyze the determinants of hypercapnia in overlap syndrome. In the comparison between overlap and OSA patients, the overlap group had a significantly higher PaCO2 (44.59 vs. 39.22 mm Hg; p < 0.01), in the presence of a similar AHI (40.46 vs. 41.59/h). Comparing overlap to COPD patients, overlap showed a significantly higher PaCO2 value (44.59 vs. 39.63 mm Hg; p < 0.005) and had significantly less severe obstructive impairment (FEV 162.93 vs. 47.31%; FEV1/FVC ratio 66.71 vs. 59.25%; p < 0.005). Anthropometric, pulmonary function, and polysomnographic data did not differ between normo- and hypercapnic overlap patients. The best model (stepwise multiple regression analysis) for predicting PaCO2 in overlap patients showed r2 value 0.65: PaO2 contributed to 38%, FEV1 to 15%, and weight to 12%. In conclusion, the occurrence of hypercapnia in overlap patients is only partially explained by the combination of overweight and reduced respiratory function, supporting the hypothesis of a multifactorial genesis.