Snoring is not associated with adverse effects on blood pressure, arterial structure or function in 8-year-old children: the Childhood Asthma Prevention Study (CAPS)

Ready to scan? A systematic review of point of care ultrasound (PoCUS) for screening of obstructive sleep apnea (OSA) in the pediatric population

STUDY OBJECTIVE

Diagnosis of obstructive sleep apnea (OSA) in pediatric practice is challenging, as screening questionnaires are inadequate and sleep studies are resource limited and time-consuming. A recent systematic review and meta-analysis of perioperative point-of-care ultrasound (PoCUS) in adults identified several parameters which correlate with OSA diagnosis and are the subject of an ongoing prospective study. The objective of this systematic review was to evaluate the usefulness of surface airway ultrasound as a PoCUS tool for OSA screening in the pediatric population.

DESIGN

Databases were searched for observational cohort studies and randomized controlled trials of patients under 18 years of age undergoing quantitative surface US measurement of extra-thoracic airway structures where correlation or association was examined either directly to OSA diagnosis or indirectly to an alternative reference measure. Diagnostic properties and correlation between US parameters (index test) and reference measures were evaluated where possible.

MAIN RESULTS

Of the initial 8499 screened articles, 12 articles (8 airway, 4 non-airway) evaluating 1237 patients were included. Six of these studies were conducted in the sleep/obesity clinic and six in in the perioperative population. Ten studies were prospective and two were cross sectional studies. Airway parameters which correlated with moderate-severe OSA were lateral pharyngeal wall thickness and total neck thickness at the retropharyngeal level. Tonsil volume was not correlated with OSA diagnosis or severity. In tonsillectomy patients, tonsil volume on preoperative ultrasound correlated well with volume of surgical specimens. Adenoid thickness correlated strongly with radiological and endoscopic measures of size and occlusion.

CONCLUSION

Ultrasound measurement in children indicates several parameters which correlate with OSA diagnosis or with other reference measurements. This has not yet been validated as a diagnostic tool, however the recent emergence of research in this area is encouraging and the findings from this review will inform future studies.

Association between self-reported snoring and arterial stiffness: data from the Brisighella Heart Study

The correlation of both obstructive sleep apnoea syndrome (OSAS) and snoring with cardiovascular risk is well known, but its investigation is complex and not suitable for studying large cohorts of subjects. Thus, we prospectively evaluated 1476 non-pharmacologically treated subjects selected from the last survey of the Brisighella Heart Study. Snoring and sleep apnoea were investigated asking the subjects if they were aware of snoring during the night, and if this was associated with episodes of apnoea. A full set of clinical and laboratory parameters were evaluated, while augmentation index (AIx), and pulse wave velocity (PWV) were recorded with the Vicorder(®) apparatus. A logistic regression analysis identifies as main independent predictors of AIx age (OR 1.058, 95% CI 1.043-1.065, p < 0.001), Body Mass Index (OR 1.046, 95% CI 1.014-1.079, p = 0.005), and apolipoprotein B (OR 1.014, 95% CI 1.004-1.023, p = 0.001). The main independent predictors of PWV are snoring (OR 1.215, 95% CI 1.083-1.390, p < 0.001), and snoring with apnoea (OR 1.351, 95% CI 1.135-1.598, p = 0.014), age (OR 1.078, 95% CI 1.052-1.089, p < 0.001), serum uric acid [SUA] (OR 1.093, 95% CI 1.026-1.151, p < 0.001) and mean arterial pressure (OR 1.042, 95% CI 1.024-1.056, p < 0.001). In conclusion, in our cohort of overall healthy subjects, self-reported snoring and sleep apnoea are independently associated with a higher PVW, and AIx is statistically significantly higher in snorers with or without sleep apnoea than in non-snorers. Body Mass Index and apolipoprotein B are associated with AIx, while SUA and mean arterial pressure are related to PWV.

Blood pressure regulation, autonomic control and sleep disordered breathing in children

Sleep disordered breathing (SDB) ranges in severity from primary snoring (PS) to obstructive sleep apnoea (OSA). In adults, SDB is associated with adverse cardiovascular consequences which are mediated, in part, by autonomic dysfunction. Although SDB is common in children, fewer paediatric studies have investigated these cardiovascular effects. Initial research focused on those with OSA, indeed children with PS were occasionally utilised as the comparison control group. However, it is essential to understand the ramifications of this disorder in all its severities, as currently the milder forms of SDB are often untreated. Methodologies used to assess autonomic function in children with SDB include blood pressure (BP), BP variability, baroreflex sensitivity, heart rate variability, peripheral arterial tonometry and catecholamine assays. The aim of this review was to summarise the findings of paediatric studies to date and explore the relationship between autonomic dysfunction and SDB in children, paying particular attention to the roles of disease severity and/or age. This review found evidence of autonomic dysfunction in children with SDB during both wakefulness and sleep. BP dysregulation, elevated generalised sympathetic activity and impairment of autonomic reflexes occur in school-aged children and adolescents with SDB. The adverse effects of SDB seem somewhat less in young children, although more studies are needed. There is mounting evidence that the cardiovascular and autonomic consequences of SDB are not limited to those with OSA, but are also evident in children with PS. The severity of disease and age of onset of autonomic consequences may be important guides for the treatment of SDB.

Hypertension and obstructive sleep apnea

Obstructive sleep apnea (OSA) is increasingly being recognized as a major health burden with strong focus on the associated cardiovascular risk. Studies from the last two decades have provided strong evidence for a causal role of OSA in the development of systemic hypertension. The acute physiological changes that occur during apnea promote nocturnal hypertension and may lead to the development of sustained daytime hypertension via the pathways of sympathetic activation, inflammation, oxidative stress, and endothelial dysfunction. This review will focus on the acute hemodynamic disturbances and associated intermittent hypoxia that characterize OSA and the potential pathophysiological mechanisms responsible for the development of hypertension in OSA. In addition the epidemiology of OSA and hypertension, as well as the role of treatment of OSA, in improving blood pressure control will be examined.