Nocturnal dipping is preserved in children with sleep disordered breathing regardless of its severity.

OBJECTIVE: Sleep disordered breathing (SDB) in adults has been associated with a loss of nocturnal dipping in blood pressure (BP) and heart rate, however, there have been limited studies in children. We measured BP non-invasively and continuously overnight in 105 children aged 7-12 with a range of severities of SDB and 36 non-snoring controls to examine nocturnal dipping profiles. STUDY DESIGN: Children with SDB were divided into three severity groups according to their obstructive apnea hypopnea index. Nocturnal dipping profiles across sleep stages were described both as a proportion of children exhibiting a ≥10% fall in systolic arterial pressure (SAP) and heart rate (HR) from wake to sleep and according to SAP sleep/SAP wake ratio as extreme dippers (ratio ≤ 0.8), dippers (ratio < 0.8 and ≤0.9), non-dippers (ratio < 0.9 and ≤1.0), and reverse dippers (ratio > 1.0). RESULTS: The mean fall in BP between wake and NREM 1/2, SWS, and REM sleep was not different between the groups and there were no differences between the dipping profiles of children in each group. CONCLUSIONS: SDB did not alter nocturnal dipping patterns of BP and HR compared to controls, a finding which may suggest that these young children have not been exposed to the effects of SDB long enough or that SDB severity was not great enough to affect nocturnal dipping profiles. However, further studies are required to determine if the elevated BP previously reported in this group of children will have long-term effects on the cardiovascular system.

EEG spectral analysis of apnoeic events confirms visual scoring in childhood sleep disordered breathing.

PURPOSE: This study compared electroencephalogram (EEG) spectral analysis with standard visual scoring to assess the validity of clinical classification of arousals at respiratory event termination in children with obstructive sleep apnoea (OSA). METHODS: Twenty children (six M/14 F) aged 7-12 years, diagnosed with moderate to severe OSA participated in this study. Overnight polysomnography was performed, and sleep stages and arousals visually scored using clinical paediatric measures. The EEG was spectrally analysed in six 5-s epochs across respiratory events, namely two consecutive 5-s epochs pre-event onset and a 5s epoch post-event onset, 5-s before event termination, and two contiguous 5-s epochs post-event termination. EEG spectral power distribution was compared across respiratory events visually categorised as full cortical arousals, subcortical activations, or non-arousals using specialised software (Sleep Research System 5.0). RESULTS: There was no difference in power spectra between events in REM and NREM sleep and these were combined. There was a statistically significant fall from pre-arousal baseline values in delta and theta spectral power at respiratory event terminations associated with cortical arousals only. No change in power was detected at respiratory event terminations associated with subcortical activations or non-arousals. CONCLUSIONS: The lack of significant EEG spectral power changes at respiratory event terminations not associated with visually identified cortical arousals indicates undetected micro-arousals are not present. The results support the validity of clinical classifications of arousals at respiratory event termination.

Elevated blood pressure during sleep and wake in children with sleep-disordered breathing.

OBJECTIVE: Sleep-disordered breathing (SDB) in adults has been associated with elevated blood pressure (BP); however, the effects of severity of SDB on BP in children are uncertain. We addressed this issue by measuring BP noninvasively and continuously during sleep in children with a range of severities of SDB and in a group of nonsnoring control children. METHODS: A total of 105 children referred for assessment of SDB and 36 nonsnoring controls were studied. Routine polysomnography (PSG) was performed with continuous BP monitoring. Children were assigned to groups according to obstructive apnea/hypopnea index (OAHI). BP data were categorized as quiet awake (recorded before sleep onset), non-rapid eye movement sleep 1 and 2 combined, slow-wave sleep, and rapid eye movement sleep. RESULTS: BP during awake before sleep onset and during overnight sleep was elevated by 10 to 15 mm Hg in the 3 SDB groups compared with the control group; this finding was independent of SDB severity. BP during stable sleep (with respiratory events and movements excluded) was also elevated in the children with OSA compared with the control group. BP was elevated in rapid eye movement sleep compared with the non-rapid eye movement sleep, and heart rate was higher during wake state than in all sleep states. CONCLUSIONS: We recorded BP continuously overnight and found that SDB, regardless of the severity, was associated with increased BP during sleep and wake compared with nonsnoring control children. These findings highlight the importance of considering the cardiovascular effects of SDB of any severity in children, and the need to review current clinical management that focuses primarily on more severe SDB.

Cognitive and academic functions are impaired in children with all severities of sleep-disordered breathing.

STUDY OBJECTIVE: The impact of the broad spectrum of SDB severity on cognition in childhood has not been well studied. This study investigated cognitive function in children with varying severities of SDB and control children with no history of SDB. METHODS: One hundred thirty-seven children (75 M) aged 7-12 were studied. Overnight polysomnography (PSG) classified children into four groups: primary snoring (PS) (n = 59), mild obstructive sleep apnea syndrome (OSAS) (n = 24), moderate/severe OSAS (n = 19), and controls (n = 35). Cognition was measured with a short battery of psychological tests including the Wechsler Abbreviated Scale of Intelligence (WASI), the Wide Range Achievement Test-3rd Edition (WRAT-3), the Rey Complex Figure Test (RCFT) and the Controlled Oral Word Association Test (COWAT). RESULTS: There was lower general intellectual ability in all children with SDB regardless of severity. Higher rates of impairment were also noted on measures of executive and academic functioning in children with SDB. CONCLUSIONS: Our findings suggest that neurocognitive deficits are common in children with SDB regardless of disease severity, highlighting that such difficulties may be present in children in the community who snore but are otherwise healthy; thus our results have important implications for the treatment of pediatric SDB.

Neurobehavioral function is impaired in children with all severities of sleep disordered breathing.

OBJECTIVE: Sleep disordered breathing (SDB) is common in children and ranges in severity from primary snoring (PS), to obstructive sleep apnea syndrome (OSAS). This study investigated everyday function (behavior, attention, executive skills) in children with varying degrees of SDB and control children with no history of SDB recruited from the community. METHODS: One hundred thirty-six children aged 7-12 were studied. Routine overnight polysomnography (PSG) classified children into 4 groups: PS (n=59), mild OSAS (n=24), moderate/severe OSAS (n=18), and controls (n=35). Behavioral function and behavioral aspects of attention and executive function were assessed using the Child Behavior Checklist (CBCL) and the Behavior Rating Inventory of Executive Function (BRIEF). RESULTS: Children with all severities of SDB had significantly higher rates of total, internalizing and externalizing behavioral problems compared to control children. Increased rates of behavioral executive dysfunction were also found across the SDB spectrum. CONCLUSION: Our findings suggest that behavioral, attention, and executive function difficulties are present in children with PS as well as OSAS. These results have implications for the treatment of milder forms of SDB, particularly PS, which is commonly viewed as benign.

Determining sleep quality in children with sleep disordered breathing: EEG spectral analysis compared with conventional polysomnography.

STUDY OBJECTIVES: To identify the extent of sleep disruption in children with various severities of sleep disordered breathing (SDB) using both conventional visually scored assessment of sleep stages and arousal indices together with EEG power spectral analysis. DESIGN: Sleep stages and power spectral analysis of the sleep EEG in children with varying severities of SDB with matched control subjects with no history of snoring were compared across the whole night, across sequential hours from sleep onset, and across sleep stages. MEASUREMENTS: Overnight polysomnography was performed on 90 children (49M/41F) aged 7-12 y with SDB and 30 age-matched healthy controls (13M/17F). Sleep stages were visually scored and the EEG spectra were analyzed in 5-s epochs. RESULTS: Conventional visual scoring indicated that, although sleep duration was reduced in severely affected children, sleep quality during the essential stages of SWS and REM was preserved, as evidenced by the lack of any significant decrease in their duration in SDB severity groups. This finding was supported by the lack of substantial differences in EEG spectral power between the groups over the whole night, within specific hours, and in individual sleep stages. CONCLUSIONS: Both conventional scoring and EEG spectral analysis indicated only minor disruptions to sleep quality in children with SDB when assessed across the night, in any specific hour of the night, or in any specific sleep stage. These results suggest that reduced daytime functioning previously reported in children with SDB may not be due to sleep disruption. We speculate that in children, in contrast to adults, a stronger sleep drive may preserve sleep quality even in severe SDB.

Arousal from sleep mechanisms in infants.

Arousals from sleep allow sleep to continue in the face of stimuli that normally elicit responses during wakefulness and also permit awakening. Such an adaptive mechanism implies that any malfunction may have clinical importance. Inadequate control of arousal in infants and children is associated with a variety of sleep-related problems. An excessive propensity to arouse from sleep favors the development of repeated sleep disruptions and insomnia, with impairment of daytime alertness and performance. A lack of an adequate arousal response to a noxious nocturnal stimulus reduces an infant's chances of autoresuscitation, and thus survival, increasing the risk for Sudden Infant Death Syndrome (SIDS). The study of arousability is complicated by many factors including the definition of an arousal; the scoring methodology; the techniques used (spontaneous arousability versus arousal responses to endogenous or exogenous stimuli); and the confounding factors that complicate the determination of arousal thresholds by changing the sleeper's responses to a given stimulus such as prenatal drug, alcohol, or cigarette use. Infant age and previous sleep deprivation also modify thresholds. Other confounding factors include time of night, sleep stages, the sleeper's body position, and sleeping conditions. In this paper, we will review these different aspects for the study of arousals in infants and also report the importance of these studies for the understanding of the pathophysiology of some clinical conditions, particularly SIDS.

Acute cardiovascular changes with obstructive events in children with sleep disordered breathing.

STUDY OBJECTIVES: Obstructive apneas in adults are associated with acute changes in blood pressure (BP) and heart rate (HR) that may contribute to poor cardiovascular outcome. Children with sleep disordered breathing (SDB) are similarly at risk for cardiovascular complications. We aimed to test the hypothesis that BP and HR are augmented during obstructive events in children equivalent to levels reported in adults. DESIGN: Beat-by-beat mean arterial pressure (MAP) and HR were analyzed over the course of obstructive events (pre, early, late, and post-event) during NREM and REM sleep and compared using 2-way ANOVA with post hoc analyses. SETTING: Pediatric sleep laboratory. PATIENTS OR PARTICIPANTS: 30 children (15M/15F) aged 7-12 y referred for investigation of SDB INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: All children underwent overnight polysomnography with continuous BP recording. MAP and HR increased significantly from late to post event in both sleep states (mean +/- SEM, NREM: MAP, 74 +/- 3 to 93 +/- 3 mm Hg; HR, 76 +/- 2 to 97 +/- 2 bpm. REM: MAP, 76 +/- 3 to 89 +/- 3 mm Hg; HR, 76 +/- 2 to 91 +/- 2 bpm. P < 0.05 for all). NREM sleep state and arousal from sleep were significant independent predictors of the magnitude of cardiovascular change from late to post event (P < 0.05 for all). CONCLUSIONS: Children with SDB experience significant changes in HR and BP during obstructive events with magnitudes that are similar to levels reported in adults. These changes are more pronounced during NREM sleep and with arousal. These acute cardiovascular changes may have important implications for poor cardiovascular outcome in children with OSA as repetitive cardiovascular perturbations may contribute to the development of hypertension.

Central apnoeas have significant effects on blood pressure and heart rate in children.

Brief central apnoeas (CAs) during sleep are common in children and are not usually considered clinically significant unless associated with oxygen desaturation. CAs can occur spontaneously or following a movement or sigh. The aim of this study was to investigate acute cardiovascular changes associated with CAs in children. Beat-by-beat mean arterial pressure (MAP) and heart rate (HR) were analysed across CAs, and spontaneous and movement-induced events were compared using two-way analysis of variance with post hoc analyses. Fifty-three children (28 male/25 female) aged 7-12 years referred for investigation of sleep-disordered breathing (SDB) and 21 age-matched healthy controls (8 male/13 female) were studied. Children underwent routine clinical polysomnography with continuous blood pressure (BP) recordings. Movement-induced, but not spontaneous, CAs were more frequent in children with mild or moderate/severe obstructive sleep apnoea (OSA) compared with healthy controls (P < 0.05 for both). Movement-induced CAs were associated with significantly larger MAP and HR changes across the event compared with spontaneous CAs. The percentage changes in MAP and HR between late-event and post-event were significantly greater for movement-induced compared with spontaneous CAs (MAP 20.6 +/- 2.3 versus 12.2 +/- 1.8%, P < 0.01; HR 28.2 +/- 2.6 versus 14.7 +/- 2.5%, P < 0.001). This study demonstrates that movement-induced CAs are more common in children with OSA, and are associated with significantly greater changes in HR and BP compared with spontaneous CAs. These data suggest that movement-induced CAs should be considered when assessing the cardiovascular impact of SDB.