Long-term changes in heart rate variability in elementary school–aged children with sleep-disordered breathing

ObjectiveSleep-disordered breathing (SDB) in adults and children has been associated with reduced heart rate variability (HRV) indicative of autonomic dysfunction, which in turn is associated with an increased risk for cardiovascular morbidity. However, the long-term effects of pediatric SDB that has either resolved or remains unresolved on HRV are unknown.MethodsForty Children with previously diagnosed SDB and 20 non snoring controls underwent repeat overnight polysomnography (PSG) four years after the original diagnosis. At follow-up, children aged 11 to 16 years were categorized into resolved (absence of snoring and obstructive apnea hypopnea index [OAHI] ⩽ 1) or unresolved (continued to snore or had an OAHI > 1) groups. HRV was assessed using power spectral analysis for each sleep stage.ResultsThere were no group differences in age, sex or body mass index (BMI) z score. Both the resolved and unresolved SDB groups showed significant improvement in OAHI. The control, resolved, and unresolved groups all showed a significant reduction in total power (P < .001), low-frequency (LF) power (P < .05), high-frequency (HF) power (P < .001), and an increase in the LF/HF ratio (P < .001) from baseline to follow-up in all sleep stages.ConclusionsHRV did not differ between non snoring children and children with resolved and unresolved SDB four years after initial diagnosis, concomitant with a significant reduction in OAHI in both SDB groups. All groups demonstrated a decrease in HRV from baseline to follow-up which may reflect an age-related phenomenon in these children.     

The effect of childhood obstructive sleep apnea on ambulatory blood pressure is modulated by the distribution of respiratory events during rapid eye movement and nonrapid eye movement sleep

ObjectiveWe aimed to investigate if different childhood obstructive sleep apnea (OSA) subtypes, namely rapid eye movement (REM)-related, nonrapid eye movement (NREM)-related and stage-independent OSA would exert different effects on ambulatory blood pressure (ABP).MethodsData from our previous school-based cross-sectional study were reanalyzed. Subjects who had an obstructive apnea–hypopnea index (OAHI) between 1 and 10 events per hour and a total REM sleep duration of >30 min were included in our analysis. REM-related and NREM-related OSA were defined as a ratio of OAHI in REM sleep (OAHI_REM) to OAHI in NREM sleep (OAHI_NREM) of >2 and <0.5, respectively. The others were classified as stage-independent OSA.ResultsA total of 162 subjects were included in the analysis. In the mild OSA (OAHI, 1–5 events/h) subgroup, no significant differences in any ABP parameters were found between OSA subtypes. On the other hand, in subjects with moderate OSA (OAHI, 5–10 events/h), the REM-related OSA subtype had a significantly lower daytime systolic blood pressure (SBP) z score (−0.13 ± 0.90 cf 1.15 ± 0.67; P = .012) and nighttime SBP z score (0.29 ± 1.06 cf 1.48 ± 0.88, P = .039) than the stage-independent OSA subtype. Linear regression analyses revealed that OAHI_NREM but not OAHI_REM was significantly associated with both daytime (P = .008) and nighttime SBP (P = .042) after controlling for age, gender, and body size.ConclusionChildren with obstructive events mainly in REM sleep may have less cardiovascular complications than those with stage-independent OSA.     

Sleep-disordered breathing does not affect nocturnal dipping,as assessed by pulse transit time,in preschool children: evidence for early intervention to prevent adverse cardiovascular effects?

ObjectiveSleep-disordered breathing (SDB) is associated with reduced nocturnal dipping of blood pressure (BP) and sleep disruption in adults, and these features confer an increased risk of cardiovascular events. As SDB prevalence in children peaks during the preschool years, we investigated nocturnal dipping and sleep fragmentation in preschool children with SDB.MethodsChildren (3–5 years; n = 163) grouped by obstructive apnoea hypopnoea index (OAHI): control, no snoring history and OAHI ⩽1 event/h; primary snoring, OAHI ⩽1 event/h; mild SDB, >1–⩽5 events/h; moderate–severe SDB, >5 events/h. Pulse transit time (PTT), an inverse continuous indicator of BP changes, and heart rate (HR) during total sleep time and the first period of rapid eye movement (REM), non-REM (NREM)1/2 and NREM3/4 sleep were expressed as percentage change from wake before sleep onset. The sleep fragmentation index (SFI) was calculated as the number of sleep stage transitions or awakenings per hour of sleep.ResultsThere were no group differences in the change in PTT or HR from wake to total sleep time or to individual sleep stages or in the proportion of children in the quartile with the smallest change in PTT during total sleep. Children with moderate–severe SDB had higher SFI than primary snoring (PS) or mild SDB groups (p < 0.05 for both) and controls (p = 0.07).ConclusionsIn contrast to adults, nocturnal dipping is preserved in young children with SDB, despite increased sleep fragmentation. As there is evidence that nocturnal dipping is similarly preserved at the school age, childhood may pose a window of opportunity for resolution of SDB when the cardiovascular effects are less marked.     

Long-term changes in blood pressure control in elementary school-aged children with sleep-disordered breathing

ObjectiveIn adults sleep-disordered breathing (SDB) has been associated with impaired baroreflex control of blood pressure (BP), which has been linked to increased cardiovascular morbidity. In children, the long-term effects of SDB on baroreflex sensitivity (BRS) and BP variability (BPV) are unknown.MethodsChildren previously diagnosed with SDB (n = 40) and 20 nonsnoring controls aged 11–16 y underwent overnight polysomnography with continuous BP measurement, four years after the original diagnosis. At follow-up, SDB was categorized as resolved (absence of snoring and obstructive apnea hypopnea index (OAHI) ⩽ 1) or unresolved (continued to snore or had an OAHI > 1). BRS and BPV were calculated using cross-spectral analysis and power spectral analysis, respectively.ResultsOnly children with resolved obstructive sleep apnea (OSA) at follow-up demonstrated an increase in BRS from 9.7 ± 3 (ms mmHg⁻¹) at baseline to 11.8 ± 4 (ms mmHg⁻¹) at follow-up (P = .03). However, children with all severities of both resolved and unresolved SDB showed a significant decrease in BPV from baseline to follow-up (a decrease in total power BPV (P < .05) and a shift in BPV spectra away from respiratory-related frequencies (increased low-frequency/high-frequency [LF/HF] ratio, P < .01). The change in OAHI was the sole determinant of change in BRS, HF power, and LF/HF ratio.ConclusionsImprovement in SDB was associated with improved BP control, regardless if SDB was treated or spontaneously resolved four years after initial diagnosis. Our findings highlight the importance of monitoring children to ensure improvement of SDB and reduce the risk for cardiovascular morbidity in the future.     

Time course of EEG slow-wave activity in pre-school children with sleep disordered breathing: A possible mechanism for daytime deficits?

BackgroundDaytime deficits in children with sleep disordered breathing (SDB) are theorized to result from hypoxic insult to the developing brain or fragmented sleep. Yet, these do not explain why deficits occur in primary snorers (PS). The time course of slow wave EEG activity (SWA), a proxy of homeostatic regulation and cortical maturation, may provide insight.MethodsClinical and control subjects (N = 175: mean age 4.3 ± 0.9 y: 61% male) participated in overnight polysomnography (PSG). Standard sleep scoring and power spectral analyses were conducted on EEG (C4/A1; 0.5–<3.9 Hz). Univariate ANOVA’s evaluated group differences in sleep stages and respiratory parameters. Repeated-measures ANCOVA evaluated group differences in the time course of SWA.ResultsFour groups were classified: controls (OAHI ? 1 event/h; no clinical history); PS (OAHI ? 1 event/h; clinical history); mild OSA (OAHI=1–5 events/h); and moderate to severe OSA (MS OSA: OAHI > 5 events/h). Group differences were found in the percentage of time spent in NREM Stages 1 and 4 (p < 0.001) and in the time course of SWA. PS and Mild OSA children had higher SWA in the first NREM period than controls (p < 0.05). All SDB groups had higher SWA in the fourth NREM period (p < 0.01).ConclusionsThese results suggest enhanced sleep pressure but impaired restorative sleep function in pre-school children with SDB, providing new insights into the possible mechanism for daytime deficits observed in all severities of SDB.     

The effect of sildenafil on sleep respiratory parameters and heart rate variability in obstructive sleep apnea

ObjectiveTo evaluate the magnitude of effects of sildenafil on respiratory parameters and heart rate variability (HRV) in slow wave sleep (SWS) and REM sleep of patients with severe obstructive sleep apnea (OSA).MethodsThirteen male patients with untreated severe OSA (aged 43 ± 10 years, body mass index of 26.7 ± 1.9 kg/m²) were studied on two nights, one with sildenafil 50 mg and one with a placebo, in a double-blind, randomized fashion. All-night polysomnography and HRV were simultaneously recorded. Short-term HRV measures were performed in apnea-free intervals. Respiratory parameters were separately assessed in non-REM and REM sleep and compared to total sleep time (TST). Short-term HRV analysis was conducted in samples with regular respiration obtained in SWS and REM sleep.ResultsComparing to placebo, during sildenafil night there was an increase in apnea–hypopnea index (AHI) in TST and also in non-REM and REM sleep. Increase in central AHI occurred in non-REM sleep; increase in obstructive AHI and decrease in oxyhemoglobin saturation occurred in both non-REM and REM sleep. Additionally, an increase in arousal index and in low/high frequency component of HRV ratio (LF/HF) was significant only in REM sleep. Correlation between sleep architecture and respiratory parameters were more frequent in non-REM sleep for placebo and in REM sleep for sildenafil.ConclusionIn severe OSA, the use of sildenafil 50 mg at bedtime plays a detrimental role on respiratory parameters in both non-REM and REM sleep, fragmentation in REM sleep, and a prolonged increase in LH/HF component of HRV after resumption of ventilation.     

Sleep architecture in school-aged children with primary snoring

ObjectiveWe aimed to examine if sleep architecture was altered in school-aged children with primary snoring (PS).MethodsChildren ages 6 to 13 years from 13 primary schools were randomly recruited. A validated obstructive sleep apnea (OSA) screening questionnaire was completed by their parents. Children at high risk for OSA and a randomly chosen low-risk group were invited to undergo overnight polysomnography (PSG) and clinical examination. Participants were classified into healthy controls, PS, mild OSA, and moderate to severe OSA (MS OSA) groups for comparison.ResultsA total of 619 participants underwent PSG (mean age, 10.0 ± 1.8 years; 396 (64.0%) boys; 524 (84.7%) prepubertal). For the cohort as a whole, there were no significant differences in measures of sleep architecture between PS and nonsnoring healthy controls. In the multiple regression model, percentage of nonrapid eye movement (NREM) stage 1 (N1) sleep had a significantly positive association, whereas percentage of slow-wave sleep (SWS) had a significantly negative association with sleep-disordered breathing (SDB) severity after controlling for age, gender, body mass index (BMI) z score, and pubertal status. In prepubertal children with PS, no significant disruption of sleep architecture was found. However, pubertal adolescent PS participants had significantly higher adjusted percentage of N1 sleep and wake after sleep onset (WASO) compared to healthy controls.ConclusionsPS did not exert significant adverse influences on normal sleep architecture in prepubertal school-aged children. Nevertheless, pubertal adolescents with PS had increased N1 sleep and WASO.     

A four year follow-up of sleep and respiratory measures in elementary school-aged children with sleep disordered breathing

ObjectiveLittle is known of the long-term prognosis of children treated for sleep disordered breathing (SDB) and even less of children with milder forms of SDB who remain untreated. We aimed to investigate the long-term sleep and respiratory outcomes of children with a range of SDB severities.Methods41 children with SDB and 20 non snoring controls (mean age, 12.9 ± 0.2 y), underwent repeat overnight polysomnography (PSG) 4.0 ± 0.3 years after initial diagnosis. SDB severity, presence of snoring, sleep and respiratory parameters, sleep fragmentation index (SFI), the Pediatric Daytime Sleepiness Scale (PDSS), Sleep Disturbance Scale for Children (SDSC), and obstructive sleep apnea 18-item quality of life questionnaire were re assessed. Children with SDB were grouped into resolved (no snoring and obstructive apnea–hypopnea index [OAHI] <1) and unresolved (snoring or an OAHI ⩾1).ResultsAt follow-up OAHI was reduced in both SDB groups (p < 0.05); however, 54% (n = 22) of children still continued to snore, having either persistent or new OSA (n = 4). In this unresolved group, sleep was significantly disrupted; % nonrapid eye movement stage 1 (NREM1) sleep and SFI were increased (p < 0.05), and total sleep time (TST) and sleep efficiency were decreased compared to the resolved and control groups (p < 0.05). Overall, 29% of children were treated, and of these, 67% had resolved SDB. SDB groups had higher PDSS, SDSC, and OSA-18 scores compared to controls at follow-up (p < 0.01).ConclusionsOur study demonstrated that although SDB improved in the long-term, more than 50% of children had residual SDB (mostly primary snoring) and sleep disturbance. As even mild forms of SDB are known to have adverse cardiovascular, learning, and behavioral outcomes, which have implications for the health of these children.     

Impaired blood pressure control in children with obstructive sleep apnea

BackgroundObstructive sleep apnea (OSA) in adults has been associated with hypertension, low baroreflex sensitivity (BRS), a delayed heart rate response to changing blood pressure (heart period delay [HPD]), and increased blood pressure variability (BPV). Poor BRS may contribute to hypertension by impairing the control of blood pressure (BP), with increased BPV and HPD. Although children with OSA have elevated BP, there are scant data on BRS, BPV, or HPD in this group.Methods105 children ages 7–12 years referred for assessment of OSA and 36 nonsnoring controls were studied. Overnight polysomnography (PSG) was performed with continuous BP monitoring. Subjects were assigned to groups according to their obstructive apnea–hypopnea index (OAHI): primary snoring (PS) (OAHI ⩽1 event/h), mild OSA (OAHI > 1–⩽5 events/h) and moderate/severe (MS) OSA (OAHI > 5 events/h). BRS and HPD were calculated using cross spectral analysis and BPV using power spectral analysis.ResultsSubjects with OSA had significantly lower BRS (p < .05 for both) and a longer HPD (PS and MS OSA, p < .01; mild OSA, p < .05) response to spontaneous BP changes compared with controls. In all frequencies of BPV, the MS group had higher power compared with the control and PS groups (low frequency [LF], p < .05; high frequency [HF], p < .001).ConclusionsOur study demonstrates reduced BRS, longer HPD, and increased BPV in subjects with OSA compared to controls. This finding suggests that children with OSA have altered baroreflex function. Longitudinal studies are required to ascertain if this dampening of the normal baroreflex response can be reversed with treatment.     

REM and NREM sleep-state distribution of respiratory events in habitually snoring school-aged community children

BackgroundStudies ascribe different functions to rapid eye movement (REM) and non-rapid eye movement (NREM) sleep, such that their disruption could result in discrepant clinical outcomes. Although sleep architecture is globally preserved in children with obstructive sleep apnoea (OSA), it is considered to be an REM sleep REMS disorder. Furthermore, body position during sleep affects the occurrence of respiratory events, while the presence of obesity has been claimed to affect sleep-state distribution of respiratory disturbance.MethodsTo explore the distribution of respiratory events during REMS and NREM sleep NREMS and its potential predictors, a cross-sectional analysis of 335 overnight sleep studies in snoring children from the community was conducted. The ratio of REMS to NREMS respiratory events was compared, and potential associations were assessed using general linear modelling (GLM).ResultsChildren were 7.3 ± 1.2 years old and had a body mass index (BMI) z-score of 1.0 ± 1.3. The obstructive apnoea–hypopnea index (OAHI) was 1.7 ± 3 and 45.8% of children had an apnoea–hypopnea index (AHI) >1 h^?1 total sleep time (TST). Obstructive respiratory events were 3.8 times more likely in REMS (2.0 h^?1) than NREMS (0.5 h^?1), and the GLM revealed distinctive predictive associations for the apnoeic and hypopneic indices separately, and for body position, the latter indicating that the REMS/NREMS distribution of respiratory events depends on body position.ConclusionObstructive respiratory events are predominantly, albeit not exclusively, present in REMS in school-aged children. NREMS respiratory events are more likely in the presence of lower oxyhaemoglobin saturations during event, side body position and in African–American children. However, REMS dominance is not affected by either BMI z-score or obesity. Our findings suggest that incorporating comprehensive respiratory event profiles of children may enhance our understanding of the pathophysiology and adverse outcomes in the context of paediatric OSA.     

A double-blind,crossover study of Doxazosin and Enalapril on peripheral vascular tone and nocturnal blood pressure in sleep apnea patients

ObjectivePulse wave attenuation, which occurs in association with obstructive sleep apnea (OSA), is sympathetically mediated. We compared the effect of Doxazosin (DO, a peripheral α-receptor inhibitor) and Enalapril (EN, an ACE inhibitor) on digital vasoconstriction and nocturnal blood pressure (BP) in hypertensive OSA patients.MethodsA double-blind, crossover study comparing equipotent dosages of DO (4 mg/day for 2 weeks with 8 mg/day for an additional 2 weeks) and EN (10 mg/day and 20 mg/day, respectively) was undertaken in 16 male OSA patients (age 55 ± 7 years, body mass index 30.1 ± 3.8 kg/m²) with hypertension. Assessments including ambulatory 24-h BP, full-night polysomnography with simultaneous peripheral arterial tone (PAT) and beat-to-beat finger BP monitoring (Finapres) were made at the end of each treatment period. Nighttime BP and digital vasoconstrictions associated with apneic events (measured as the ratio of PAT amplitudes during and after apneas) were analyzed.ResultsThere were no differences between the two treatments in the 24-h BP profile and OSA severity. But the nighttime average beat-to-beat finger BP was significantly higher under DO treatment (systolic BP 129 ± 13 vs. 119 ± 23 mm Hg, P = 0.02; diastolic BP 81 ± 12 vs. 74 ± 14 mm Hg, P = 0.04, DO and EN respectively). In a linear mixed effects regression model, the PAT ratio during apnea increased 5.3% under DO compared with EN (P < 0.0001). Each percentage decrease of apneic related oxygen desaturation was associated with 0.9% decrease in the PAT ratio (P < 0.0001). REM sleep was associated with 2.2% decrease of PAT ratio compared to NREM sleep (P = 0.002).ConclusionDigital vasoconstrictions associated with apneic events are α-receptor mediated. DO compared to EN has a proportionally poor effect on nocturnal BP control in OSA patients, which may be due to the enhanced sympathetic nervous system activity characteristic of this condition.     

Multiple sleep latency measures in narcolepsy and behaviourally induced insufficient sleep syndrome

BackgroundShort mean latencies to the first epoch of non-rapid eye movement sleep stage 1 (NREM1) and the presence of ?2 sleep onset REM (SOREM) periods on multiple sleep latency test (MSLT) occur in both narcolepsy–cataplexy (NC) and behaviourally induced insufficient sleep syndrome (BIISS). It is not known whether specific MSLT findings help differentiate the two disorders.MethodsWe analyzed MSLT data including sleep latencies to and between different sleep stages of 60 age-, gender- and body mass index (BMI)-matched subjects (hypocretin-deficient NC, actigraphy-confirmed BIISS, healthy controls: each 20).ResultsMean latency (in minutes) to NREM1 sleep was significantly shorter in NC (1.8 ± 1.5) than in BIISS (4.7 ± 2.1, p < 0.001) and controls (11.4 ± 3.3, p < 0.001). Mean latency to NREM2 sleep was similar in NC (8.6 ± 4.7) and BIISS (8.1 ± 2.7, p = 0.64); latency to either NREM2 or rapid eye movement (REM) sleep (i.e., the sum of the sleep latency to NREM1 and the duration of the first NREM1 sleep sequence), however, was shorter in NC (4.4 ± 2.9) than in BIISS (7.9 ± 3.5, p < 0.001). Referring to all naps with SOREM periods, the sequence NREM1–REM–NREM2 was more common (71%) in NC than in BIISS (15%, p < 0.001), reflecting the shorter latency from NREM1 to NREM2 in BIISS (3.7 ± 2.5) than in NC (6.1 ± 5.9, p < 0.001).ConclusionsOur findings show that both sleepiness (as measured by NREM1 sleep latency) and REM sleep propensity are higher in NC than in BIISS. Furthermore, our finding of frequent REM sleep prior to NREM2 sleep in NC is in line with the recent assumption of an insufficient NREM sleep intensity in NC. Together with detailed clinical interviews, sleep logs, actigraphy, and nocturnal polysomnography, mean sleep latencies to NREM1 ?2.5 min, the presence of multiple SOREM periods, and the sequence NREM1–REM–NREM2 may be the best MSLT measures to discriminate NC from BIISS.     

Clinical and polysomnographic characteristics and response to continuous positive airway pressure therapy in obstructive sleep apnea patients with nightmares

ObjectiveTo assess the characteristics of obstructive sleep apnea (OSA) patients with nightmares and the effects of continuous positive airway pressure (CPAP) therapy on nightmares.MethodsConsecutive patients referred with a clinical suspicion of OSA underwent attended overnight sleep studies. OSA and nightmares were diagnosed according to the American Academy of Sleep Medicine (AASM) criteria, and CPAP titration was performed in accordance with the AASM guidelines. A follow-up visit was performed 3 months later, and the patients with nightmares were divided into two groups: group 1 used CPAP with good compliance, whereas group 2 refused CPAP treatment and did not use other alternative treatments for OSA.ResultsThe study included 99 patients who had been diagnosed with OSA with nightmares. Their mean age was 47.2 ± 11.2 years, and they had a mean apnea–hypopnea index (AHI) of 36.5 ± 34.3/h. Also included were 124 patients with OSA without nightmares. The mean age of these patients was 45.4 ± 13.9 years, and they had a mean AHI of 40.2 ± 35/h. The patients with nightmares had a significantly higher AHI during rapid eye movement sleep (REM) compared with the patients without nightmares (51.7 ± 28.1 vs 39.8 ± 31.9/h). Logistic regression analysis revealed that the REM-AHI and interrupted sleep at night were independent predictors of nightmares in the OSA patients. Nightmares disappeared in 91% of the patients who used CPAP compared with 36% of patients who refused to use CPAP (p < 0.001).ConclusionNightmares in OSA patients are associated with a higher REM-AHI. CPAP therapy results in a significant improvement in nightmare occurrence.     

Impact of obstructive sleep apnea on the 24-h metabolic hormone profile

ObjectiveObstructive sleep apnea (OSA) has been associated with metabolic disorders. Sleep-disordered breathing could generate an altered rhythm in the expression of metabolic hormones, which could predispose to metabolic disorders. The aim of this study was to evaluate the effect of sleep apnea on diurnal variations in metabolic hormones.MethodsThirty-seven male, newly diagnosed, patients with OSA with an apnea–hypopnea index (AHI) ⩾20/h and 11 male controls (AHI <10/h) matched for body mass index (±3 kg/m²) were included. Six different samples were obtained from each subject during a period of 24 h. Levels of the metabolic hormones ghrelin, leptin, resistin, and adiponectin were measured in plasma by immunoassay.ResultsPatients with OSA (AHI (mean ± SD) 46 ± 26/h) were older than the controls (42 ± 9 vs 33 ± 9 years, P = 0.01). Differences in metabolic hormones between groups did not reach statistical significance at any point in the evaluation. No significant differences were observed in the area under the curve for any of the hormones analysed. Likewise, we did not detect diurnal variations in metabolic hormones.ConclusionsThe results of this study indicate that the day–night variations in the levels of several metabolic hormones are not influenced by the presence of sleep apnea.     

Effects of long-term use of clonazepam on nonrapid eye movement sleep patterns in rapid eye movement sleep behavior disorder

ObjectiveWe aim to analyze in detail the characteristics of nonrapid eye movement (NREM) sleep in drug-free patients with idiopathic rapid eye movement sleep behavior disorder (iRBD). We compare drug-free iRBD patients to both normal controls and drug-free patients with narcolepsy/RBD and evaluate the changes following the long-term use of bedtime clonazepam.Participants and methodsForty-six participants were recruited: 15 with iRBD (13 men, 2 women; mean age, 65.8 ± 4.39 years), 13 with narcolepsy/RBD (10 men, 3 women; mean age, 63.0 ± 6.73 years), and 18 normal controls (10 men, 8 women; mean age 69.4 ± 7.72 years). Sleep was video polysomnographically recorded and the RBD severity scale (RBDSS) was obtained. Chin electromyography (EMG) amplitude was quantitatively assessed and the atonia index was computed. Additionally, NREM sleep instability was evaluated using an automatic quantitative analysis. Participants with iRBD were re-evaluated after 2.75 ± 1.62 years of regular therapy with 0.5 to 1-mg clonazepam at bedtime.ResultsSlow transient electroencephalography (EEG) events were increased in iRBD and decreased in narcolepsy/RBD, while fast transient events decreased in iRBD and increased in narcolepsy/RBD. During rapid eye movement (REM) sleep the atonia index was reduced in both iRBD and narcolepsy/RBD groups and during NREM sleep atonia index was increased in iRBD participants, remaining low in narcolepsy/RBD participants. After long-term therapy with clonazepam, wakefulness after sleep onset was decreased together with an increase in both slow-wave sleep (SWS) and sleep stage 2, in which the latter reached statistical significance; sleep stages 1 and 2 instability significantly decreased and the duration of EEG transients also slightly but significantly decreased. Finally, chin tone was not modified by clonazepam.ConclusionsOur study confirms that clonazepam modifies some aspects of NREM sleep in iRBD participants with a decrease in its instability. Moreover, we also show that a complex modification of sleep chin atonia exists in these participants, which also involves NREM sleep; for iRBD more complex neuropathologic models encompassing REM sleep and NREM sleep mechanisms are needed.     

Anticyclic modulated ventilation versus continuous positive airway pressure in patients with coexisting obstructive sleep apnea and Cheyne–Stokes respiration: a randomized crossover trial

BackgroundAlthough coexisting obstructive sleep apnea (OSA) and Cheyne–Stokes respiration (CSR) occur frequently in patients with heart diseases, optimal treatment remains unclear. Positive airway pressure (PAP) effectively treats OSA and adaptive servo-ventilation (ASV) has been shown to improve CSR. We compared a new treatment algorithm combining automatic continuous positive airway pressure (APAP) and ASV (anticyclic modulated ventilation, ACMV) versus continuous positive airway pressure (CPAP).MethodsThirty-nine patients (35 male, four female; aged 65.5 ± 9.7 years; body mass index, 31.0 ± 5.9 kg/m²) with underlying heart disease and coexisting OSA and CSR were enrolled. After diagnostic polysomnography (PSG) and CPAP titration, patients were randomized either to CPAP or to ACMV for four weeks of treatment in a crossover design.ResultsTotal apnea–hypopnea index (AHI) was 49.0 ± 18.8/h at baseline, 12.3 ± 14.6/h with CPAP (P < 0.001 vs baseline), and 3.7 ± 5.6/h with ACMV (P < 0.001 vs baseline and vs CPAP). Obstructive AHI was 20.7 ± 14.4/h at baseline, 5.1 ± 9.3/h with CPAP (P < 0.001 vs baseline), and 0.4 ± 0.4/h with ACMV (P < 0.001 vs baseline and vs CPAP). Central AHI was 28.3 ± 13.4/h at baseline, 7.2 ± 9.7/h with CPAP (P < 0.001 vs baseline) and 3.3 ± 5.4/h with ACMV (P < 0.001 vs baseline and vs CPAP). Ejection fraction was increased significantly (from 38.6 ± 15.6 to 44.4 ± 12.2%) only with ACMV. Subjective sleepiness significantly improved only with CPAP whereas objective sleep quality and treatment adherence were not different between both treatment modalities.ConclusionACMV is an effective treatment option in patients with coexisting OSA and CSR. It is superior to CPAP in reducing total AHI as well as obstructive and central AHI.     

Ambulatory blood pressure before and after adenotonsillectomy in children with obstructive sleep apnea

IntroductionHypertension is found to be associated with obstructive sleep apnea (OSA) in both children and adults. But data on the effect of blood pressure after adenotonsillectomy (AT) for children with OSA are limited and controversial.ObjectiveTo assess the impact of AT on different parameters of 24-h ambulatory blood pressure monitoring in children with OSA.MethodsWe retrospectively reviewed records of OSA children who had undergone AT and a repeated sleep polysomnography after AT from 2001 to 2008.ResultsForty-four children were identified and included in the analysis. The mean apnea-hypopnea index (AHI) dropped from 14.14 ± 15.9 to 3.3 ± 7.1. (p < 0.001). Twenty (45%) were cured of OSA. After AT, the diastolic BP load decreased significantly. Six out of eight (75%) hypertensive children became normotensive after surgery. For the pre-AT hypertensive group, both systolic and diastolic blood pressure decreased significantly during sleep after AT. However, eight children who were normotensive before AT became hypertensive after AT. These 10 post-AT hypertensive patients were more likely to have post-AT AHI > 1 than the post-AT normotensive group, although the difference did not reach statistical significance.ConclusionIn the current cohort of OSA children, 44% were cured of OSA and a significant decrease in overall diastolic blood pressure load in 24-h ambulatory blood pressure was achieved after adenotonsillectomy for children with OSA. But hypertension may persist or even occur in those previously normotensive children despite the improvement in AHI. Persistence of OSA may be a risk factor and further study is required. Cure of OSA should not be assumed after AT and follow-up PSG should be performed together with 24-h ambulatory blood pressure monitoring. In light of the current findings, long term study of the blood pressure is warranted for children with OSA.     

Reciprocal interactions of obstructive sleep apnea and hypertension associated with ACE I/D polymorphism in males

BackgroundThe angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism gene contributes to the genesis of hypertension (HTN) and may help explain the relationship between obstructive sleep apnea (OSA) and HTN. However, ACE is a pleiotropic gene that has several influences, including skeletal muscle and control of ventilation. We therefore tested the hypothesis that ACE polymorphism influences OSA severity.MethodsMale OSA patients (apnea-hypopnea index [AHI] > 5 events/h) from 2 university sleep centers were evaluated by polysomnography and ACE I/D polymorphism genotyping.ResultsWe studied 266 males with OSA (age = 48 ± 13y, body mass index = 29 ± 5kg/m², AHI = 34 ± 25events/h). HTN was present in 114 patients (43%) who were older (p < 0.01), heavier (p < 0.05) and had more severe OSA (p < 0.01). The I allele was associated with HTN in patients with mild to moderate OSA (p < 0.01), but not in those with severe OSA. ACE I/D polymorphism was not associated with apnea severity among normotensive patients. In contrast, the only variables independently associated with OSA severity among patients with hypertension in multivariate analysis were BMI (OR = 1.12) and II genotype (OR = 0.27).ConclusionsOur results indicate reciprocal interactions between OSA and HTN with ACE I/D polymorphism, suggesting that among hypertensive OSA males, the homozygous ACE I allele protects from severe OSA.     

Teenage sleep-disordered breathing: Recurrence of syndrome

ObjectivesThe study aims to better understand the reappearance of sleep apnoea in adolescents considered cured of obstructive sleep apnoea (OSA) following adenotonsillectomy and orthodontic treatment.Study designThe study employs a retrospective analysis of 29 adolescents (nine girls and 20 boys) with OSA previously treated with adenotonsillectomy and orthodontia at a mean age of 7.5 years. During follow-up at 11 and 14 years of age, patients were clinically evaluated, filled the Pediatric Sleep Questionnaire (PSQ) and had systematic cephalometric X-rays performed by orthodontists. Polysomnographic (PSG) data were compared at the time of OSA diagnosis, following surgical and orthodontic treatment and during pubertal follow-up evaluation.ResultsFollowing the diagnosis of OSA and treatment with adenotonsillectomy and rapid maxillary expansion (Apnea–Hypopnea Index (AHI) 0.4 ± 0.4), children were re-evaluated at a mean age of 11 years. During follow-up at 14 years, all children had normal body mass indices (BMIs). Teenagers were subdivided into two groups based on complaints: Nine asymptomatic subjects (seven girls and two boys) and 20 subjects with decline in school performance, presence of fatigue, indicators of sleep-phase delays and, less frequently, specific symptoms of daytime sleepiness and snoring. Presence of mouth breathing, abnormal AHI and RDI and significant reduction of posterior airway space (PAS) was demonstrated during repeat polysomnography and cephalometry. Compared to cephalometry obtained at a mean of 11 years of age, there was a significant reduction of PAS of 2.3 ± 0.4 mm at a mean age of 14 years.ConclusionPreviously suggested recurrence of OSA during teenage years has again been demonstrated in this small group of subjects. Prospective investigations are needed to establish frequency of risk, especially in non-orthodontically treated children.     

Sleep and cardiometabolic function in obese adolescent girls with polycystic ovary syndrome

ObjectiveTo compare the polysomnography findings and cardiometabolic function among adolescent girls with polycystic ovary syndrome (PCOS) and matched female and male controls.MethodRetrospective chart review of electronic medical records of 28 girls with PCOS (age: 16.8 ± 1.9 years, body mass index (BMI) Z-score 2.4 ± 0.4), 28 control females (age: 17.1 ± 1.8, BMI Z-score 2.4 ± 0.3) and 28 control males (age: 16.6 ± 1.6, BMI Z-score 2.5 ± 0.5) in a tertiary care centre.ResultsThe prevalence of obstructive sleep apnoea (OSA) was higher in girls with PCOS compared to control females (16/28 (57%) vs. 4/28(14.3%), p < 0.01); however, it was comparable to that of the control males (16/28(57%) vs. 21/28(75%), p = 0.4). Girls with PCOS had a significantly higher prevalence of insulin resistance compared to control females and control males (20/28 (71.4%) vs. 9/22 (41.0%) (p = 0.04) vs. 8/23 (34.8%) (p = 0.01). Among girls with PCOS, those with OSA had significantly higher proportions of metabolic syndrome (MetS) (9/16 (56.3%) vs. 1/12 (8.3%) p = 0.03), higher insulin resistance (14/16 (87.5%) vs. 6/12 (50%), p = 0.04), elevated daytime systolic blood pressure (128.4 ± 12.8 vs. 115.6 ± 11.4, p < 0.01), lower high-density lipoprotein (HDL) (38.6 ± 8.7 vs. 49 ± 10.9, p = 0.01) and elevated triglycerides (TG) (149.7 ± 87.7 vs. 93.3 ± 25.8, p = 0.03) compared to those without OSA.ConclusionsWe report a higher prevalence of OSA and metabolic dysfunction in a selected group of obese girls with PCOS referred with sleep-related complaints compared to BMI-matched control girls without PCOS. We also report higher prevalence of cardiometabolic dysfunction in girls with PCOS and OSA compared to girls with PCOS without OSA.