Knarik Tamanyan

Risk factors for obstructive sleep apnoea in Australian children

This study aims to determine whether demographic or clinical factors predict obstructive sleep apnoea (OSA) severity in Australian children.

Regional brain tissue changes and associations with disease severity in children with sleep-disordered breathing

Study Objectives Children with sleep-disordered breathing (SDB) exhibit behavioral, cognitive, and autonomic deficits, suggestive of neural injury. We assessed whether the tissue alterations resulted from acute or chronic processes, and if alterations correlated with disease severity. Methods Brain tissue integrity was examined with mean diffusivity (MD) (3.0-Tesla scanner) in 20 non-snoring controls (mean age±sem, 12.2±0.6y; 10 male) and 18 children with SDB (12.3±0.7y; 11 male). Sleep, cognitive, and behavioral measures were compared between groups following overnight polysomnography using Students t-tests. Whole-brain MD maps were realigned and averaged, normalized, smoothed, and compared between groups using ANCOVA (covariates; age, gender, and socioeconomic status). Partial correlations were calculated between whole-brain smoothed MD maps and obstructive apnea hypopnea indices (OAHI). Results Age, gender, and sleep variables did not differ between groups. The SDB group showed higher OAHI, body mass indices, and systolic blood pressure. Significantly reduced MD values (acute changes) appeared in the hippocampus, insula, thalamus, temporal and occipital cortices, and cerebellum, but were increased (chronic damage) in the frontal and prefrontal cortices in the SDB group over controls. Both positive and negative correlations appeared with extent of tissue changes and disease severity. Externalizing and Total Problem Behaviors were significantly higher in SDB children. Verbal, performance and total IQ scores trended lower, and behavioral scores trended higher. Conclusions Pediatric SDB is accompanied by predominantly acute brain changes in areas that regulate autonomic, cognitive, and mood functions, and chronic changes in frontal cortices essential for behavioral control. Interventions need to be keyed to address acute vs chronic injury.

Age Effects on Cerebral Oxygenation and Behavior in Children with Sleep-disordered Breathing

Rationale: Childhood sleep‐disordered breathing ranges in severity from primary snoring to obstructive sleep apnea and is associated with behavioral and neurocognitive deficits. It remains unknown why children with primary snoring, who do not experience peripheral oxygen desaturation or sleep fragmentation, experience similar daytime deficits as those with obstructive sleep apnea or why effects are age‐dependent. Objectives: To examine cerebral tissue oxygenation and oxygen extraction as an explanation for daytime deficits in children with primary snoring. Methods: Children referred for suspected sleep‐disordered breathing and nonsnoring control subjects underwent overnight polysomnography with near‐infrared spectroscopy. Children were categorized into 3‐ to 6‐year (n = 87) and 7‐ to 12‐year (n = 72) old groups, and according to the obstructive apnea‐hypopnea index into primary snoring (≤1 event/h), mild (>1‐5 events/h), and moderate/severe obstructive sleep apnea (>5 events/h). Cognitive and behavioral performance were assessed. Measurements and Main Results: In the 3‐ to 6‐year group, there were no differences in cerebral oxygenation or oxygen extraction between severity groups. In the 7‐ to 12‐year group, cerebral oxygenation was significantly lower, although these differences were small, in control subjects versus primary snoring during quiet wakefulness before sleep onset, N1, and REM. Oxygen extraction was significantly higher in control subjects versus primary snoring during N1 sleep, with no differences between primary snoring and obstructive sleep apnea groups. Cerebral oxygenation was not associated with cognitive performance in either age group or behavior in the 3‐ to 6‐year group; however, it was associated with behavior in the school‐aged children. Conclusions: Children with sleep‐disordered breathing are able to maintain cerebral oxygenation, and the small changes observed are not related to cognitive deficits. However, in older children these differences were related to behavioral measures.

Obesity and anthropometric determinants of autonomic control in children with sleep-disordered breathing—which measurements matter?

BackgroundObesity and anthropometric measurements predict more severe sleep-disordered breathing (SDB) in children, and are associated with cardiovascular risk factors in children without SDB. We aimed to investigate whether anthropometric measurements predicted autonomic control in children with SDB. We hypothesised that anthropometric measures would be significant predictors of decreased heart rate variability.MethodsChildren (3–17 years) with SDB (n = 298) and non-snoring controls (n = 126) underwent polysomnography. BMI z-score, neck, waist and hip circumference were recorded. Heart rate variability, indicating autonomic control, was analysed during wake, non-rapid eye movement stages N1, N2 and N3, and rapid eye movement (REM) sleep. The determinants of heart rate variability (low-frequency power [LF], high-frequency power [HF] and LF/HF ratio) were analysed using multiple stepwise linear regression. Independent variables were age, neck, waist and hip circumference, neck-to-waist ratio, waist-to-hip ratio and waist-to-height ratio, obstructive apnoea hypopnoea index, arousal index and SpO2 nadir.ResultsWaist and hip circumference, and waist-to-height ratio were significant negative determinants of both HF and LF power during wake, reflecting dampened autonomic control (LF: waist/height ratio, B = −1917 (95% CI: −3640, −194), p = 0.03; HF: hip circumference, B = −27, (−48, −7), p = 0.01), N1&2 (LF/HF: hip circumference, B = 0.01 (0.004, 0.024), p = 0.005) and N3 (LF: waist/height ratio, B = −2495, (−4005, −986), p = 0.001; HF, hip circumference, B = −54, (−102, −6), p = 0.03; LF/HF, waist circumference, B = 0.01, (0.004, 0.015), p = 0.002). Age was the strongest determinant of heart rate variability during wake and sleep.ConclusionThis study suggests that while age is a determinant of autonomic control in children with SDB, the strongest modifiable factor determining dampened autonomic control is increased central adiposity, as reflected in the waist and hip circumference and the waist-to-height ratio.