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Purpose: Studies reveal that rostral fluid shifts due to body posture changes from standing to lying down may narrow the upper airway. However, without credible and direct experimental evidence, it remains unclear what the role of natural fluid redistribution in the neck is in affecting obstructive sleep apnea (OSA) severity. Our aim is using direct experimental evidence to determine whether or not postural fluid shifts affect OSA severity. Methods: We performed overnight polysomnography on two consecutive nights for 22 men. The bed was set horizontally on the control night, while its tail part was lowered by 30° on the experimental night to reduce the amount of fluid shifted into the neck. We measured sleep and anthropometric parameters on each night. Results: The mean (95% CI) apnea-hypopnea index (AHI) in the supine head and trunk position decreased from 66.6 events per hour (57.6–75.6) to 61.2 (52.0–70.4) (t = 4.507, p <0.001), and the oxygen desaturation index from 69.5 events per hour (56.4–82.6) to 61.6 (50.5–72.6) (t = 3.293, p = 0.004), from the control to the experimental night with a decrease in the change of leg fluid volume from 17.7% (15.7–19.8) to 4.7% (1.9–7.5) (t = 11.659, p < 0.001). Conclusions: Our findings provide direct experimental evidence to show that natural fluid shift caused by the day-to-night posture change does contribute to OSA pathogenesis and severity. It is likely that the neck fluid increase from an actual day-to-night position change, with 90° change in posture, would produce a much larger AHI increase than the 11.2% found in this study, which contains only a 30° change in posture. These findings suggest that reducing the amount of fluid in the neck region may relieve airway obstructions for patients with moderate and severe OSA. [ABSTRACT FROM AUTHOR]

Introduction: Many studies on the impact of type 2 diabetes mellitus (T2DM) on sleep breathing have shown a higher prevalence and severity of sleep apnea-hypopnea syndrome (SAHS) in those with T2DM. Moreover, an increased activity of the sympathetic nervous system has been described in both pathologies. This cross-sectional study aimed to assess sympathetic activity in patients with T2DM, and to investigate the relationship between sympathetic activity and polysomnographic parameters.Materials and Methods: Thirty-six patients with T2DM without known clinical macrovascular nor pulmonary disease and 11 controls underwent respiratory polygraphy, and their cardiac variability and 24-h urine total metanephrines were measured.Results: SAHS was highly prevalent with a mean apnea-hypopnea index (AHI) in the range of moderate SAHS. In patients with T2DM, the nocturnal concentration of total metanephrines in urine were higher than diurnal levels [247.0 (120.0–1375.0) vs. 210.0 (92.0–670.0), p = 0.039]. The nocturnal total metanephrine concentration was positively and significantly associatedwith the percentage of sleeping time spent with oxygen saturation

Introduction: Many studies on the impact of type 2 diabetes mellitus (T2DM) on sleep breathing have shown a higher prevalence and severity of sleep apnea-hypopnea syndrome (SAHS) in those with T2DM. Moreover, an increased activity of the sympathetic nervous system has been described in both pathologies. This cross-sectional study aimed to assess sympathetic activity in patients with T2DM, and to investigate the relationship between sympathetic activity and polysomnographic parameters. Materials and Methods: Thirty-six patients with T2DM without known clinical macrovascular nor pulmonary disease and 11 controls underwent respiratory polygraphy, and their cardiac variability and 24-h urine total metanephrines were measured. Results: SAHS was highly prevalent with a mean apnea-hypopnea index (AHI) in the range of moderate SAHS. In patients with T2DM, the nocturnal concentration of total metanephrines in urine were higher than diurnal levels [247.0 (120.0–1375.0) vs. 210.0 (92.0–670.0), p = 0.039]. The nocturnal total metanephrine concentration was positively and significantly associatedwith the percentage of sleeping time spent with oxygen saturation <90%(CT90). In the entire population and in subjects with T2DM, the multivariate regression analysis showed a direct interaction between the nocturnal concentration of urine metanephrines and the CT90. Conclusion: These findings suggest that the increase in sympathetic activity previously described in patients with T2DM could be mediated through nocturnal breathing disturbances. The diagnosis and treatment of SAHS may influence sympathetic activity disorders and may contribute to an improvement in T2DM and cardiovascular risk. [ABSTRACT FROM AUTHOR]

Background: Rhinitis and obstructive sleep apnea (OSA) often coexist during childhood. To delineate this clinical association, we examined OSA severity and polysomnogram (PSG) features in children with rhinitis and OSA. Given that rapid-eye-movement (REM) sleep is characterized by nasal congestion, we hypothesized that children with rhinitis have more REM-related breathing abnormalities. Methods: We conducted a retrospective cross-sectional analysis of 145 children with PSG-diagnosed OSA. Outcomes included PSG parameters and obstructive apnea-hypopnea index (OAHI) during REM and non-REM. Linear multivariable models examined the joint effect of rhinitis and OSA parameters with control for potential confounders. Results: Rhinitis was present in 43% of children with OSA (n = 63) but overall OAHI severity was unaffected by the presence of rhinitis. In contrast, OAHI during REM sleep in children with moderate-severe OSA was significantly increased in subjects with rhinitis and OSA (44.1/hr; SE = 6.4) compared with those with OSA alone (28.2/hr; SE = 3.8). Conclusion: Rhinitis is highly prevalent in children with OSA. Although OSA is not more severe in children with rhinitis, they do have a distinct OSA phenotype characterized by more REM-related OSA. Further research is needed to delineate the link between REM-sleep and the physiology of the nose during health and disease. [ABSTRACT FROM AUTHOR]