Does treatment of SDB in children improve cardiovascular outcome?

Efficacy of adenotonsillectomy on pediatric obstructive sleep apnea and related outcomes: A narrative review of current evidence

This review summarizes the current evidence in systematic reviews, meta-analysis and randomized controlled trials regarding adenotonsillectomy outcomes in pediatric obstructive sleep apnea (OSA). Adenotonsillectomy is effective in treating OSA in children without co-morbidities, despite postoperative residual OSA remained in roughly half of these children. For children with comorbidities such as Down syndrome, Prader-Willi syndrome, sickle cell disease, or cerebral palsy, adenotonsillectomy is less effective and associated with more postoperative complications than that in children without comorbidities. For other OSA-related outcomes, evidence from meta-analyses and randomized controlled trials confirm adenotonsillectomy results in improvement of subjective OSA-related outcomes (e.g. symptoms, behaviors, and quality of life), but the results in objective OSA-related outcomes (e.g. cardiometabolic parameters or neurocognitive functions) are inconsistent. Future studies should focus on randomized controlled trials comparing objective OSA-related outcomes and the long-term effects of adenotonsillectomy in children with OSA.

Effects of sleep-disordered breathing on serum lipid levels in children:a case control study

BACKGROUND

Sleep-disordered breathing (SDB) during childhood is common and includes a range of breathing abnormalities that range from primary snoring (PS) to obstructive sleep apnea syndrome (OSAS).Studies have shown that not only OSAS, but also PS, which is originally considered harmless, could cause cardiovascular, cognitive, behavioral, and psychosocial problems. Many researches are focused on the relation of OSA and serum lipid levels. However, little studies are focused on PS and serum lipid levels in children.We evaluated whether serum lipid (total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C),low-density lipoprotein cholesterol (LDL-C)) concentrations were associated with specific components of SDB, including indices of oxygen reduction index, lowest oxygen saturation, mean oxygen saturation. And we explored whether serum lipid levels were associated with different degree sleep disordered (PS and OSA group) and obese.

METHODS

This was a cross-sectional study. Children who were complained by their guardians with habitual snoring and(or) mouth breathing were collected in the SDB group. Normal children without sleep problem were matched in the control group. Subjects in the SDB group underwent polysomnography. The serum lipid profiles of all the children included TC, TG, HDL-C and LDL-C concentrations were measured by appropriate enzymatic assays.

RESULTS

A total of 241 with Apnea/Hypopnea Index ≥ 5 (AHI) were assigned to the OSAS group and the remaining 155 with normal AHI were assigned to the PS group. The values of TC, TG, LDL-C and LDL/HDL were significantly higher in the OSAS group than in the PS group, and the values in the PS group were significantly higher than the control group. Multiple regression analysis revealed serum TG only correlated negatively with lowest oxygen saturation. Body mass index-z score has a positive effect on TG in all the 1310 children (P = 0.031) and in SDB 396 children(P = 0.012). The level of serum TG in obese group was significantly higher than that in non-obese group.

CONCLUSIONS

SDB had a very obvious effect on blood lipids, whereas PS without apnea and hypoxia. Obese only affects the aggregation of TG.

TRIAL REGISTRATION

ChiCTR1900026807(2019.10.23).

Secondary Analyses of the Childhood Adenotonsillectomy Trial: A Narrative Review

Importance

Adenotonsillectomy, performed for approximately 500 000 children annually in the US alone, is the first line of treatment of pediatric obstructive sleep apnea (OSA). The Childhood Adenotonsillectomy Trial (CHAT), the first randomized clinical trial to test the efficacy of adenotonsillectomy, compared the management of pediatric nonsevere OSA by early adenotonsillectomy (eAT) vs watchful waiting with supportive care. Since the publication of the primary article in 2013, the CHAT study data set were made available via the National Sleep Research Resource, which allowed researchers to address a range of additional clinical questions relevant to the care of children with OSA. This review focuses on secondary analyses associated with the CHAT data set as grouped by the outcome of interest.

Observations

The results of most secondary analyses suggest that children who underwent eAT experienced the greatest improvements in symptom burden, sleepiness, parent-reported behavior, and quality of life. Changes in other domains, such as cognition, cardiovascular physiology, and metabolic indicators, were modest and selective. The associations between most treatment outcomes and polysomnographic parameters were weak. Symptoms were poor predictors of OSA severity. The results from these secondary analyses benefitted from the rigor of multicenter design and centralized polysomnography interpretation in CHAT. However, the exclusion of younger preschool-aged children and children with primary snoring limited the generalizability of findings. In addition, because caregivers were not masked, some of the parent-reported outcomes may have been inflated.

Conclusions and Relevance

The results of this narrative review suggest that CHAT provides a model for future OSA-related studies in children for design, conduct, and subsequent reuse of the study data set, and its findings have advanced our understanding of the pathophysiology and management of pediatric nonsevere OSA. Directions for future research include whether the findings from this landmark study are generalizable to younger children and children with primary snoring and severe OSA. Similar studies may help address practice variability associated with pediatric OSA and help identify children who are most likely to benefit from undergoing eAT.

Pediatric obstructive sleep-disordered breathing is associated with arterial stiffness

The association between obstructive sleep-disordered breathing (oSDB) and arterial stiffness, an independent predictor of cardiovascular outcomes, is not well established in children. This study compared cardiovascular parameters between healthy and oSDB children and aimed to identify predictors of arterial stiffness indices in children with oSDB. Cross-sectional study realized in a tertiary hospital from June 2018 to January 2020. Forty-eight children (3 to 10 years old) with clinical diagnosis of oSDB and indication for adenotonsillectomy and 24 controls were evaluated. Cardiovascular parameters were measured non-invasively by brachial artery oscillometry with a portable device. The main arterial stiffness indices assessed were augmentation index and pulse wave velocity, both derived from the aortic pulse wave. In the oSDB group, the questionnaires Obstructive Sleep Apnea-18 (OSA-18) and Pediatric Quality of Life Inventory version 4.0 (PedsQL 4.0) were applied. The oSDB group had higher values of reflection coefficient (p = 0.044) and augmentation index (p = 0.003) than the control group. Stepwise multiple regression analysis revealed that age, female sex, reflection coefficient, and systolic volume were independent predictors of augmentation index. Higher pulse wave velocity values were associated with worse quality of life assessed by PedsQL 4.0 questionnaire. There was no association with OSA-18. The vascular and hemodynamic parameters were similar in both groups.Conclusion: Children with oSDB have increased augmentation index, an independent predictor of cardiovascular outcomes. The early identification of subclinical cardiovascular changes reinforces the importance of treating the disease, as well as changing lifestyle habits, to prevent complications in adulthood. What is Known: • The association between oSDB and cardiovascular risk in adults is well described in the literature. • Children with oSDB, regardless of their weight or sex, have higher PWV values when compared to non-snoring children. What is New: • Children with oSDB have augmented arterial stiffness, evidenced by the increase in AIx@75, measured non-invasively by brachial artery oscillometry with a portable device. • Low quality of life and therefore a high disease burden in children with oSDB may be a risk factor for arterial stiffness.

Sleep-Disordered Breathing and Cardiovascular Disease in Children and Adolescents: A Scientific Statement From the American Heart Association

Obstructive sleep apnea (OSA) is a known risk factor for cardiovascular disease in adults. It is associated with incident systemic hypertension, arrhythmia, stroke, coronary artery disease, and heart failure. OSA is common in children and adolescents, but there has been less focus on OSA as a primary risk factor for cardiovascular disease in children and adolescents. This scientific statement summarizes what is known regarding the impact of sleep‐disordered breathing and, in particular, OSA on the cardiovascular health of children and adolescents. This statement highlights what is known regarding the impact of OSA on the risk for hypertension, arrhythmia, abnormal ventricular morphology, impaired ventricular contractility, and elevated right heart pressure among children and adolescents. This scientific statement also summarizes current best practices for the diagnosis and evaluation of cardiovascular disease–related complications of OSA in children and adolescents with sleep apnea and highlights potential future research in the area of sleep‐disordered breathing and cardiovascular health during childhood and adolescence.

Bispectral Analysis of Heart Rate Variability to Characterize and Help Diagnose Pediatric Sleep Apnea

Pediatric obstructive sleep apnea (OSA) is a breathing disorder that alters heart rate variability (HRV) dynamics during sleep. HRV in children is commonly assessed through conventional spectral analysis. However, bispectral analysis provides both linearity and stationarity information and has not been applied to the assessment of HRV in pediatric OSA. Here, this work aimed to assess HRV using bispectral analysis in children with OSA for signal characterization and diagnostic purposes in two large pediatric databases (0-13 years). The first database (training set) was composed of 981 overnight ECG recordings obtained during polysomnography. The second database (test set) was a subset of the Childhood Adenotonsillectomy Trial database (757 children). We characterized three bispectral regions based on the classic HRV frequency ranges (very low frequency: 0-0.04 Hz; low frequency: 0.04-0.15 Hz; and high frequency: 0.15-0.40 Hz), as well as three OSA-specific frequency ranges obtained in recent studies (BW1: 0.001-0.005 Hz; BW2: 0.028-0.074 Hz; BWRes: a subject-adaptive respiratory region). In each region, up to 14 bispectral features were computed. The fast correlation-based filter was applied to the features obtained from the classic and OSA-specific regions, showing complementary information regarding OSA alterations in HRV. This information was then used to train multi-layer perceptron (MLP) neural networks aimed at automatically detecting pediatric OSA using three clinically defined severity classifiers. Both classic and OSA-specific MLP models showed high and similar accuracy (Acc) and areas under the receiver operating characteristic curve (AUCs) for moderate (classic regions: Acc = 81.0%, AUC = 0.774; OSA-specific regions: Acc = 81.0%, AUC = 0.791) and severe (classic regions: Acc = 91.7%, AUC = 0.847; OSA-specific regions: Acc = 89.3%, AUC = 0.841) OSA levels. Thus, the current findings highlight the usefulness of bispectral analysis on HRV to characterize and diagnose pediatric OSA.

Incidence of allergen-specific and total immunoglobulin E positivity in children undergoing adenotonsillectomy

AIM

To conduct a prospective, consecutive cohort study to evaluate the incidence of allergen-specific and total immunoglobulin E (IgE) in a paediatric population undergoing adenotonsillectomy for sleep-disordered breathing.

METHODS

A total of 64 consecutive patients presenting for adenotonsillectomy at a single centre were recruited over a period of 3 months. All patients underwent adenotonsillectomy and had allergen-specific and total IgE serum testing at the time of anaesthesia induction. Pre-operative history and examination were conducted to determine clinical allergy. Caregivers completed the Sleep-Related Breathing Disorder scale of the Paediatric Sleep Questionnaire and the Mini Rhinoconjunctivitis Quality of Life Questionnaire at baseline and at 6 weeks post-operatively.

RESULTS

A total of 37 (57.8%) patients had either allergen-specific or total IgE positivity. House dust mite was the most prevalent allergen-specific IgE finding, being present in moderate to high levels in 14 (21.9%) patients. A total of 17 (26.6%) patients had a history of atopy, while 34 (53.1%) had examination findings suggestive of allergy. Neither serum IgE testing nor clinical history and examination were independently associated with residual symptoms post adenotonsillectomy. Patients with concomitant serum IgE positivity and clinical allergy had higher residual symptom scores compared to those who did not using both Sleep-Related Breathing Disorder scale of the Paediatric Sleep Questionnaire (P = 0.035) and Mini Rhinoconjunctivitis Quality of Life Questionnaire (P = 0.02) questionnaires.

CONCLUSIONS

Our prospective, consecutive cohort of patients reflect a greater incidence of serum IgE positivity compared to historical figures. When utilised with clinical findings on history and examination, serum IgE is a useful adjunct that is associated with greater residual symptoms post-adenotonsillectomy.

Effect of adenotonsillectomy on blood pressure in children with obstructive sleep apnea: a meta-analysis

BACKGROUND

While adenotonsillectomy (T&A) is widely recognized as the first-line therapy for pediatric obstructive sleep apnea (OSA), effects of T&A on blood pressure (BP) remain unclear. This meta-analysis evaluates the associations between T&A and BP in children with OSA.

METHODS

The study protocol was registered on PROSPERO (CRD42020154425). Two authors independently searched the PubMed, Medline, EMBASE, and Cochrane databases. The keywords used were "sleep apnea syndromes," "adenotonsillectomy," and "child." A random-effects model was applied to determine office systolic BP (SBP), diastolic BP (DBP), and ambulatory BP changes.

RESULT

Twelve studies with 1193 children were analyzed (mean age: 7.6 y; 54% boys). The apnea-hypopnea index significantly reduced of 9.4 events/h (95% CI, -12.0 to -6.8) after T&A. Office SBP (-0.24 mmHg; 95% CI, -1.64 to 1.16) and DBP (-1.65 mmHg; 95% CI, -3.47 to 0.17) did not decrease significantly after surgery. No significant decreases were observed in 24-h ambulatory BP after T&A. Subgroup analysis showed a significant postoperative decrease in office SBP (-6.23 mmHg; 95% CI, -7.78 to -4.67) and DBP (-7.93 mmHg; 95% CI, -10.37 to -5.48) among children with hypertension but a slight increase in office SBP (2.50 mmHg; 95% CI, 1.14 to 3.86) and DBP (1.98 mmHg; 95% CI, -0.02 to 3.98) in those without (P for heterogeneity < 0.001).

CONCLUSION

This meta-analysis suggests the office and ambulatory BP changes after T&A in children with OSA are trivial. Moreover, children with hypertension experience a significantly greater decrease in office BP than children without hypertension.

Cardiovascular issues in obstructive sleep apnoea in children: A brief review

Obstructive sleep apnoea (OSA) is a very common disease with a prevalence that ranges from 1% to 6% in children. It is characterized by intermittent partial or complete occlusion of the upper airway during sleep, leading to recurrent arousals and disturbed sleep architecture, to neurocognitive disorders and alterations in homeostatic gas exchange. Cardiovascular complications may develop in children with OSA through various mechanisms including activation and dysregulation of the sympathetic nervous system, induction of pro-inflammatory and pro-oxidant status and increased risk of systemic hypertension. As the deleterious effects of OSA on the cardio-vascular system may start early in life, in this brief review we focused our attention both on early and late cardiological changes induced by apnoeic events in the paediatric population, by reviewing recent findings in the literature.

Use of non-invasive ventilation in children with congenital tracheal stenosis

INTRODUCTION

Congenital tracheal stenosis (CTS) is a rare airway condition characterized by complete tracheal rings. Most patients undergo a slide tracheoplasty, which greatly reduces mortality but significant morbidity remains. The assessment of sleep disordered breathing (SDB) and use of non-invasive ventilation (NIV) in these children has not been described.

AIM

To describe the presence of SDB and use of NIV in children diagnosed with CTS over a 10-year period (2005-2015).

DESIGN

Retrospective case series at a tertiary children's hospital.

RESULTS

There were 16 patients identified with CTS with a median [range] age at diagnosis of 2.5 months (0-9 months). One child died in the immediate post-operative period following a slide tracheoplasty, leaving 15 survivors. There were no later deaths during follow-up while using NIV for up to 3 years after surgery. Slide tracheoplasty was undertaken in (12/15) with long-segment tracheal stenosis. 3/15 patients had a short-segment tracheal stenosis and were managed conservatively. The use of NIV occurred in 10/15 (66.67%) patients, all of whom had long-segment CTS. Pre-operative polysomnography (PSG) showed a median (±SD) obstructive apnoea/hypopnoea index (OAHI) of 14.6/hr (±6.2) which reduced to 7.2/hour (±4.2) on NIV prior to slide tracheoplasty. The median oxygen desaturation index (ODI) before NIV use was 15.3 (±19.4) episodes/hour, which reduced to 6.3 (±11) on NIV. The median period of NIV use was 5 [1-24 months] months.

CONCLUSION

Patients with CTS have obstructed sleep disordered breathing. Trials of NIV are well-tolerated and improve sleep disordered breathing.

Obstructive sleep apnea and hypertension in pediatric chronic kidney disease

BACKGROUND

Children with chronic kidney disease (CKD) are at risk for obstructive sleep apnea (OSA) and hypertension. The objectives of this study were to explore associations between OSA severity using the apnea-hypopnea-index(AHI) and obstructive apnea-hypopnea-index(OAHI) on polysomnography (PSG), OSA symptoms, and measures of hypertension in children with CKD.

METHODS

One-night in-laboratory PSGs and 24-h ambulatory blood pressure monitoring (ABPM) were performed on children with CKD stages 2-5 (non-dialysis dependent). Sleep questionnaires, including the modified Epworth Sleepiness Scale (ESS) and the Pediatric Sleep Questionnaire (PSQ), were administered during the sleep study.

RESULTS

Nineteen children and adolescents completed a PSG and questionnaires and thirteen completed ABPMs. Mean (standard deviation) age at the time of the sleep study was 14.1 (3.2) years. Eleven (58%) participants had CKD stage two, and eight (42%) had stage 3-4. None of the participants were found to have OSA on PSG. One participant had a positive ESS score (≥ 11) and five participants had positive PSQ scores (≥  eight). Night systolic and diastolic pressures were strongly correlated with the OAHI (r = 0.67 and r = 0.69, respectively, p < 0.05), while the AHI was not correlated with any blood pressure measures.

CONCLUSIONS

Our study did not find OSA on PSG in children with predominantly mild to moderate CKD. The OAHI was found to be strongly correlated with nighttime blood pressures. Future prospective studies with a larger sample size are needed to monitor for potential progression of symptoms and findings on PSG in pediatric patients as they evolve across the spectrum of CKD.

Prevalence of sleep-disordered breathing and associations with orofacial symptoms among Saudi primary school children

Background

This study aimed to determine the prevalence of sleep-disordered breathing among primary school children in Riyadh, Saudi Arabia, and to evaluate associations between sleep-disordered breathing and respiratory conditions/orofacial symptoms.

Methods

In this cross-sectional study, 1600 questionnaires were distributed to Saudi boys and girls aged 6–12 years from 16 primary schools in Riyadh. The questionnaire covered relevant demographic and personal characteristics, presence of respiratory conditions and orofacial symptoms, and the Pediatric Sleep Questionnaire. The latter was used to assess the prevalence of symptoms of sleep-disordered breathing and was completed by the participating children’s parents.

Results

In total, 1350 completed questionnaires were returned (85% response rate). The children’ mean age was 9.2 ± 1.8 years; 733 (54.3%) were boys and 617 (45.7%) girls. Overall, 21% of children were at high risk of sleep-disordered breathing. The prevalence of snoring was 14.4% and that of sleep apnea 3.4%. Boys were at higher risk of sleep-disordered breathing than girls (P = 0.040). Children with respiratory conditions or orofacial symptoms were at higher risk of sleep-disordered breathing (P < 0.0001) than children without these conditions/symptoms.

Conclusions

Around 21% of Saudi children are at risk of sleep-disordered breathing. There is a strong association between sleep-disordered breathing symptoms and the presence of respiratory conditions or orofacial symptoms.

Effect of Adenotonsillectomy on Ambulatory Blood Pressure in Pediatric Obstructive Sleep Apnea: 6-Month Follow-up Study

Objective

To investigate 24-hour ambulatory blood pressure changes 6 months after surgery among children with obstructive sleep apnea.

Study Design

Prospective interventional study.

Setting

Tertiary medical hospital.

Subjects and Methods

Children aged 4 to 16 years with symptoms of obstructive sleep apnea (apnea-hypopnea index >1) were recruited. All children underwent adenotonsillectomy and postoperative polysomnography overnight. The 24-hour ambulatory blood pressure was measured before and 6 months after surgery.

Results

The study cohort enrolled 124 children: mean (SD) age, 7.3 (3.1) years; 73% boys. After surgery, the apnea-hypopnea index significantly decreased from 13.3 (18.1) to 3.3 (7.2) events per hour ( P < .001). Overall systolic blood pressure and diastolic blood pressure were not significantly different following surgery, while daytime systolic blood pressure was slightly increased (114.3 to 117.3 mm Hg, P < .01) postoperatively. The hypertensive group (n = 43) exhibited significantly decreased levels of overall diastolic, nighttime systolic, and nighttime diastolic blood pressure ( P < .05), and 54% of hypertensive children became nonhypertensive after surgery. The nonhypertensive group (n = 81) showed slightly increased levels of nocturnal overall systolic, daytime systolic, and nighttime systolic blood pressure. A generalized linear mixed model revealed that children with hypertension had a greater decrease in systolic and diastolic ambulatory blood pressure during the daytime and nighttime (all P < .05) than those without hypertension.

Conclusions

Ambulatory blood pressure changes after adenotonsillectomy among children with obstructive sleep apnea are minimal. The decrease in ambulatory blood pressure after surgery is more prominent for hypertensive children than nonhypertensive children.

24-Hour Ambulatory Blood Pressure after Adenotonsillectomy in Childhood Sleep Apnea

OBJECTIVE

To assess the effects of adenotonsillectomy (T&A) on ambulatory blood pressure (ABP) in childhood obstructive sleep apnea (OSA).

STUDY DESIGN

From 2012 to 2017, children aged 4-16 years with symptoms and polysomnography-diagnosed OSA (apnea-hypopnea index [AHI] >1) underwent T&A. PSG studies and 24-hour ABP monitoring were performed before and at 3 months after surgery.

RESULTS

In total, 159 children were enrolled (mean age, 7.8 ± 3.3 years; 72% male). T&A significantly reduced the AHI from 12.4 ± 15.9 events/hour to 2.7 ± 5.7 events/hour (P < .001). A decrease was observed in the children's overall diastolic blood pressure (65.1 ± 6.1 mm Hg to 63.8 ± 7.4 mm Hg, P = .04) after surgery. In subgroup analysis, 100 (63%) patients were classified as nonhypertensive, and 59 (37%) were classified as hypertensive. Linear mixed model analysis revealed that compared with the children without hypertension, those with hypertension had superior improvement in systolic and diastolic blood pressure during daytime and nighttime (all P values < .01). The ABP changes after surgery were not correlated with the AHI changes. Finally, preoperative hypertension was an independent risk factor of postoperative hypertension among these children (OR 3.66; 95% CI 1.70-7.86).

CONCLUSIONS

Overall, in children with OSA, the 24-hour ABP change after T&A is small. However, among children with preoperative hypertension, there is significant BP improvement after T&A surgery.

Association of Adenotonsillectomy With Blood Pressure Among Hypertensive and Nonhypertensive Children With Obstructive Sleep Apnea

Importance

Hypertension in childhood may continue into adulthood and lead to adverse cardiovascular outcomes. Evidence suggests that adenotonsillectomy for childhood obstructive sleep apnea (OSA) may be associated with blood pressure (BP) improvement. However, how adenotonsillectomy is associated with BP in hypertensive and nonhypertensive children with OSA remains unclear.

Objective

To investigate disparities in BP changes after adenotonsillectomy in hypertensive and nonhypertensive children with OSA.

Design, Setting, and Participants

From January 1, 2010, to April 30, 2016, children (aged <18 years) with symptoms of OSA treated at National Taiwan University Hospital were enrolled in this retrospective case series study.

Interventions

Children underwent polysomnography for diagnosis of OSA (apnea-hypopnea index >1). All children with OSA underwent adenotonsillectomy.

Main Outcomes and Measures

Preoperative and postoperative overnight polysomnographic data were obtained. Office BP was measured in a sleep center before (nocturnal BP) and after (morning) polysomnography.

Results

A total of 240 nonobese children (mean [SD] age, 7.3 [3.0] years; 160 [66.7%] male and 80 [33.3%] female) with OSA were recruited. Postoperatively, the apnea-hypopnea index decreased significantly from 12.1 to 1.7 events per hour (95% CI of difference, -12.3 to -8.4 events per hour). The whole cohort had a significant decrease in nocturnal diastolic BP (66.9 to 64.5 mm Hg; 95% CI of difference, -4.1 to -0.7 mm Hg) and morning diastolic BP (66.9 to 64.4 mm Hg; 95% CI of difference, -4.2 to -0.8 mm Hg). The number (percentage) of patients with diastolic BP in the greater than 95th percentile decreased significantly nocturnally (48 [20.0%] to 33 [13.8%]; 95% CI of difference, -12.1% to -0.4%) and in the morning (52 [21.7%] to 34 [14.2%]; 95% CI of difference, -13.6% to -1.4%). Postoperatively, hypertensive children had a significant decrease in all BP measures, including mean (SD) nocturnal and morning systolic BP (nocturnal: 107.5 [8.6] mm Hg; morning: 106.0 [9.4] mm Hg), systolic BP index (nocturnal: -4.3 [8.6]; morning: -5.7 [8.5]), diastolic BP (nocturnal: 65.1 [11.5] mm Hg; morning: 64.4 [10.1] mm Hg), and diastolic BP index (nocturnal: -10.7 [17.3]; morning: -11.6 [15.7]), whereas the nonhypertensive group had a slight increase in nocturnal systolic BP (103.8 to 105.9 mm Hg; 95% CI of difference, 0.4-3.9 mm Hg). A generalized estimating equation model for subgroup comparisons revealed that children with hypertension, compared with those without, had greater improvement in all BP measures.

Conclusions and Relevance

Hypertensive children with OSA had a significant improvement in BP after adenotonsillectomy. Hypertensive children with OSA should be screened and treated by adenotonsillectomy because proper treatment not only eases OSA symptoms but also potentially prevents future cardiovascular and end-organ disease.

Insulin Resistance and Hypertension in Obese Youth With Sleep-Disordered Breathing Treated With Positive Airway Pressure: A Prospective Multicenter Study

STUDY OBJECTIVES

There is evidence that cardiometabolic disease associated with obesity and sleep-disordered breathing (SDB) in adults is present in youth. SDB is often treated with positive airway pressure (PAP) in youth with obesity. Our aims were to determine: (1) the prevalence of cardiometabolic disease and (2) whether PAP improves markers of cardiometabolic disease, in youth with obesity and newly diagnosed moderate-severe SDB.

METHODS

A prospective multicenter cohort study was conducted in youth (8 to 16 years old) with obesity, prescribed PAP therapy for newly diagnosed moderate-severe SDB. Assessments occurred at baseline and at 6 and 12 months. Outcomes included markers of insulin resistance (change in homeostasis model assessment of insulin resistance (HOMA-IR) at 6 months = primary outcome), hypertension (24-hour ambulatory/blood pressure) and inflammation (high-sensitivity C-reactive protein: hs-CRP).

RESULTS

Twenty-seven participants were enrolled. Of those with baseline testing available, 10/25 (40%) had HOMA-IR above the 97th percentile, 10/23 (44%) were hypertensive, 16/23 (70%) had loss of nocturnal blood pressure dip and hs-CRP was elevated in 16/27 (64%). There were no significant changes over time in markers of metabolic dysfunction or blood pressure, nor between PAP-adherent and non-adherent subgroups.

CONCLUSIONS

In youth with obesity and SDB, metabolic dysfunction and hypertension were highly prevalent. There were no statistically significant improvements in cardiometabolic markers 1 year after the prescription of PAP therapy, although clinically relevant improvements were seen in insulin resistance and systolic blood pressure load, important predictors of future risk of cardiovascular disease. Larger, longer-term studies are needed to determine whether PAP improves cardiometabolic outcomes in obese youth.

COMMENTARY

A commentary on this article appears in this issue on page 1025.

Longitudinal Cardiovascular Outcomes of Sleep Disordered Breathing in Children: A Meta-Analysis and Systematic Review

Objectives

The presence of sleep disordered breathing (SDB) is known to impact long-term cardiovascular morbidity in adults; however, the long-term effects in children are poorly understood. We aimed to systematically review and synthesize studies published to date on the long-term effects of SDB in children.

Study Design

Meta-analysis and systematic review using PubMed, CINAHL, Embase, and Scopus (all indexed years).

Methods

We searched for English-language articles containing original human data from prospective studies, with ≥7 participants, in children ≤18 years of age. Data regarding study design, demographics, clinical characteristics, outcomes, level of evidence, and risk of bias were obtained. Articles were independently reviewed by three investigators. Retrospective and cross-sectional studies were excluded.

Results

Of 1701 identified abstracts, 25 articles (combined n = 1418) were ultimately included. All studies reported longitudinal outcomes following treatment of SDB, 21 studies exclusively reporting outcomes after adenotonsillectomy. Therefore, studies were combined to objectively assess the effect of SDB treatment on cardiovascular outcomes. Although all cardiovascular parameters were within the normal range at baseline, at follow-up there was a significant decrease in mean pulmonary artery pressure, right ventricular end diastolic diameter, heart rate, mitral Em/Am ratio, and C-reactive protein. There was no significant change in interventricular septum thickness, left ventricular parameters (shortening fraction, systolic and end diastolic diameters, ejection fraction, posterior wall thickness, isovolumetric relaxation time), left atrial diameter, and aortic and pulmonary valve peak velocities.

Conclusions

Studies assessing the long-term cardiovascular effects of SDB in children are limited. The available literature indicates effects on autonomic function, right, and left heart function following treatment for SDB. However, well-designed, large-scale, prospective cohort studies (using standardized outcomes) are needed to better understand the relationship of cardiovascular morbidity in the context of pediatric SDB.

Comparisons of Office and 24-Hour Ambulatory Blood Pressure Monitoring in Children with Obstructive Sleep Apnea

OBJECTIVE

To compare office blood pressure (BP) and 24-hour ambulatory BP (ABP) monitoring to facilitate the diagnosis and management of hypertension in children with obstructive sleep apnea (OSA).

STUDY DESIGN

Children aged 4-16 years with OSA-related symptoms were recruited from a tertiary referral medical center. All children underwent overnight polysomnography, office BP, and 24-hour ABP studies. Multiple linear regression analyses were applied to elucidate the association between the apnea-hypopnea index and BP. Correlation and consistency between office BP and 24-hour ABP were measured by Pearson correlation, intraclass correlation, and Bland-Altman analyses.

RESULTS

In the 163 children enrolled (mean age, 8.2 ± 3.3 years; 67% male). The prevalence of systolic hypertension at night was significantly higher in children with moderate-to-severe OSA than in those with primary snoring (44.9% vs 16.1%, P = .006). Pearson correlation and intraclass correlation analyses revealed associations between office BP and 24-hour BP, and Bland-Altman analysis indicated an agreement between office and 24-hour BP measurements. However, multiple linear regression analyses demonstrated that 24-hour BP (nighttime systolic BP and mean arterial pressure), unlike office BP, was independently associated with the apnea-hypopnea index, after adjustment for adiposity variables.

CONCLUSIONS

Twenty-four-hour ABP is more strongly correlated with OSA in children, compared with office BP.

Sleep disordered breathing and autonomic function in overweight and obese children and adolescents

Obstructive sleep apnoea (OSA), common in children with obesity, is associated with cardiovascular morbidity. Autonomic dysfunction has been suggested to be a key player in the development of these complications. We investigated the relationship between obesity, OSA and sympathetic activity in children.

191 children with obesity were included and distributed into two groups: 131 controls and 60 with OSA. Beat-to-beat RR interval data were extracted from polysomnography for heart rate variability analysis. Urinary free cortisol levels were determined.

Urinary free cortisol did not differ between groups and was not associated with OSA, independent of the level of obesity. Differences in heart rate variability measures were found: mean RR interval decreased with OSA, while low/high-frequency band ratio and mean heart rate increased with OSA. Heart rate variability measures correlated with OSA, independent of obesity parameters and age: oxygen desaturation index correlated with mean heart rate (r=0.19, p=0.009) and mean RR interval (r= −0.18, p=0.02), while high-frequency bands and low/high-frequency band ratio correlated with arterial oxygen saturation measured by pulse oximetry (S_pO2) (r= −0.20, p=0.008 and r= −0.16, p=0.04) and S_pO2 nadir (r=0.23, p=0.003 and r= −0.19, p=0.02).

These results suggest that sympathetic heart activity is increased in children with obesity and OSA. Measures of hypoxia were related to increased sympathetic tone, suggesting that intermittent hypoxia is involved in autonomic dysfunction.

Sympathetic heart activity is increased in children with obstructive sleep apnoea and obesityhttp://ow.ly/iSVc305AZRv

The effect of adenotonsillectomy for childhood sleep apnoea on cardiorespiratory control

The efficacy of adenotonsillectomy for relieving obstructive sleep apnoea symptoms in children has been firmly established, but its precise effects on cardiorespiratory control are poorly understood.

In 375 children enrolled in the Childhood Adenotonsillectomy Trial, randomised to undergo either adenotonsillectomy (n=194) or a strategy of watching waiting (n=181), respiratory rate, respiratory sinus arrhythmia and heart rate were analysed during quiet, non-apnoeic and non-hypopnoeic breathing throughout sleep at baseline and at 7 months using overnight polysomnography.

Children who underwent early adenotonsillectomy demonstrated an increase in respiratory rate post-surgery while the watchful waiting group showed no change. Heart rate and respiratory sinus arrhythmia were comparable between both arms. On assessing cardiorespiratory variables with regard to normalisation of clinical polysomnography findings during follow-up, heart rate was reduced in children who had resolution of obstructive sleep apnoea syndrome, while no differences in their respiratory rate or respiratory sinus arrhythmia were observed.

Adenotonsillectomy for obstructive sleep apnoea increases baseline respiratory rate during sleep. Normalisation of apnoea–hypopnoea index, spontaneously or via surgery, lowers heart rate. Considering the small average effect size, the clinical significance is uncertain.

Adenotonsillectomy for childhood obstructive sleep apnoea increases respiratory rate during sleephttp://ow.ly/Dptd300w9Pp

Mean Platelet Volume, Vitamin D and C Reactive Protein Levels in Normal Weight Children with Primary Snoring and Obstructive Sleep Apnea Syndrome

Introduction

Studies on Mean Platelet Volume (MPV) in children with Sleep Disordered Breathing (SDB) report conflicting results and the hypothesis of an intermittent hypoxemia leading to a systemic inflammation is reaching consensus. Vitamin D exerts anti-inflammatory properties and its deficiency has been supposed to play a role in sleep disorders. Emerging interest is rising about Primary Snoring (PS) since it is reasonable that also undetectable alteration of hypoxia might predispose to an increased production of inflammatory mediators. In this perspective, in a group of children affected by SDB, our aim was to investigate MPV, vitamin D and C Reactive Protein (CRP) levels, which had been previously evaluated separately in different studies focused only on Obstructive Sleep Apnea Syndrome (OSAS).

Materials and Methods

We enrolled 137 children: 70 healthy controls (HC), 67 affected by SDB undergoing a polysomnographic evaluation, 22 with a diagnosis of PS and 45 with a diagnosis of OSAS. All patients underwent routine biochemical evaluations including blood cell counts, CRP and vitamin D.

Results

Children affected by SDB had a mean age of 8.49±2.19 and were prevalently males (23 females, 34%; 44 males, 66%). MPV levels were higher in OSAS and PS when compared to HC; platelet count (PLT) and CRP levels were higher while Vitamin D levels were lower in children with SDB when compared to HC. MPV levels were correlated with PLT (r = -0.54; p<0.001), vitamin D (r = -0.39; p<0.001) and CRP (r = 0.21; p<0.01). A multiple regression was run to predict MPV levels from vitamin D, CRP and PLT and these variables significantly predicted MPV (F = 17.42, p<0.0001; adjusted R2 = 0.37). Only platelet count and vitamin D added statistically significantly to the prediction (p<0.05).

Conclusion

The present study provides evidence of higher MPV and lower vitamin D levels in children with PS as well as in children with OSAS, and supports the underlying inflammation, hence, highlighting the importance of an early diagnosis of this previously considered benign form of SDB.

Obstructive sleep disordered breathing in 2- to 18-year-old children: diagnosis and management

This document summarises the conclusions of a European Respiratory Society Task Force on the diagnosis and management of obstructive sleep disordered breathing (SDB) in childhood and refers to children aged 2-18 years. Prospective cohort studies describing the natural history of SDB or randomised, double-blind, placebo-controlled trials regarding its management are scarce. Selected evidence (362 articles) can be consolidated into seven management steps. SDB is suspected when symptoms or abnormalities related to upper airway obstruction are present (step 1). Central nervous or cardiovascular system morbidity, growth failure or enuresis and predictors of SDB persistence in the long-term are recognised (steps 2 and 3), and SDB severity is determined objectively preferably using polysomnography (step 4). Children with an apnoea-hypopnoea index (AHI) >5 episodes·h(-1), those with an AHI of 1-5 episodes·h(-1) and the presence of morbidity or factors predicting SDB persistence, and children with complex conditions (e.g. Down syndrome and Prader-Willi syndrome) all appear to benefit from treatment (step 5). Treatment interventions are usually implemented in a stepwise fashion addressing all abnormalities that predispose to SDB (step 6) with re-evaluation after each intervention to detect residual disease and to determine the need for additional treatment (step 7).

Blood Pressure after Surgery among Obese and Nonobese Children with Obstructive Sleep Apnea

Objectives

Treating obstructive sleep apnea in children is found to be associated with blood pressure decreases. However, exactly how adenotonsillectomy (T&A) affects blood pressure in obese and nonobese children remains unclear. This study assesses how obesity affects blood pressure in children with sleep apnea after T&A.

Study Design

Case series with chart review.

Setting

A tertiary referral center.

Subjects and Methods

From 2010 to 2012, a total of 78 children were included. Based on propensity score methods (age, sex, and preoperative apnea-hypopnea index matched), children were assigned to either the obese group (n = 39) or the nonobese group (n = 39). All children received adenotonsillectomy. We recorded clinical symptoms, preoperative overnight polysomnography (PSG), and subsequent PSG within 3 months after T&A. We measured blood pressure 3 times before PSG (nocturnal blood pressure) and after PSG (morning blood pressure) in a sleep laboratory.

Results

Following surgery, the nonobese group had a significantly decreased nocturnal diastolic blood pressure (DBP) index (–12.0 to −18.8, P = .018), morning systolic blood pressure (SBP; 111.1 to 105.8 mm Hg, P = .014), SBP index (–5.4 to −10.9, P = .008), and DBP (–12.0 to −18.7, P = .023). Nevertheless, all blood pressure parameters in the obese group were not significantly changed postoperatively. The nonobese group improved more than obese group in nocturnal and morning DBP and DBP index by 2-way analysis of variance.

Conclusion

Among the children receiving T&A as treatment for OSA, nonobese children improved more than obese children did in terms of blood pressure, allowing us to infer that obese children with OSA may benefit less from T&A in cardiovascular morbidities.

Endothelial dysfunction and oxidative stress in children with sleep disordered breathing: role of NADPH oxidase

OBJECTIVE

Oxidative stress plays a crucial role in impairing endothelial function in sleep disordered breathing (SDB) but the underlying mechanism is still undefined. The objective of this study was to evaluate the interplay between oxidative stress, assessed by serum isoprostanes (8-iso-PGF2α) and soluble NOX2-dp (sNOX2-dp), and endothelial function, assessed by flow-mediated dilation (FMD), in children with SDB and healthy controls (HC).

METHODS

One-hundred forty-four children including 45 with primary snoring (PS), 22 with obstructive sleep apnea (OSA) and 67 HC were recruited in this study; in 15 out of 22 OSA children FMD, serum 8-iso-PGF2α and sNOX2-dp were assessed before and after one month post adeno-tonsillectomy (AT).

RESULTS

Compared with HC, OSA and PS children had significantly higher sNOX2-dp and serum 8-iso-PGF2α levels and lower FMD; compared with PS, FMD was significantly lower in OSA children. No significant difference for sNOX2-dp and serum 8-iso-PGF2α was observed between OSA and PS children. FMD was inversely correlated with sNOX2-dp levels (p<0.001) and with serum 8-iso-PGF2α (p<0.001). In multiple linear regression analysis, sNOX2-dp (p<0.001) and serum 8-iso-PGF2α (p<0.001) were the only independent predictive variables associated with FMD. AT significantly decreased sNOX2-dp and serum 8-iso-PGF2α levels (from 38.2±8.8 to 22.4±11.1 pg/ml, p<0.001, and from 281.4±69.7 to 226.0±66.4 pg/ml, p<0.001, respectively); conversely, FMD significantly increased after AT in OSA children (from 3.0±1.5 to 8.0±2.8%, p<0.001).

CONCLUSION

This study suggests that NOX2-derived oxidative stress is involved in artery dysfunction in SDB children. Such hypothesis is reinforced by FMD improvement after AT coincidentally with oxidative stress lowering.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02247167.

Severity of Childhood Obstructive Sleep Apnea and Hypertension Improved after Adenotonsillectomy

Objective

To report improvements in childhood obstructive sleep apnea (OSA) and hypertension after adenotonsillectomy.

Study Design

Case series with planned data collection.

Setting

Tertiary referral center.

Subjects and Methods

Fifty consecutive patients (36 boys and 14 girls; median age, 7.0 years) who underwent plasma knife–assisted total tonsillectomy and adenoidectomy for OSA between January 2010 and March 2013 were assessed with the body mass index z score, apnea-hypopnea index (AHI), systolic blood pressure (BP), and diastolic BP at baseline and at ≥6 months postoperatively. Changes in these parameters were statistically analyzed using nonparametric tests with the bootstrap approach.

Results

The median follow-up period was 9.6 months. Postoperatively, the median AHI significantly reduced from 9.8 to 1.6 ( P < .001). Although the median systolic BP and diastolic BP insignificantly changed in the overall group, both were significantly reduced in children with preoperative hypertension (systolic: from 119.0 to 113.0 [ P = .038]; diastolic: from 79.0 to 68.0 [ P = .005]). Accordingly, the hypertension rate significantly reduced from 34% to 14% ( P = .006). However, the change in OSA severity was not well correlated with the change in hypertension severity. In multiple logistic regression analysis with forward selection, a combination of preoperative hypertension and severe OSA was a significant predictor of postoperative hypertension (relative risk, 15.4; 95% confidence interval, 3.7-64.3; P < .001).

Conclusion

The decreased hypertension rate indicates that a reduction of the AHI is not all that matters after adenotonsillectomy in childhood OSA. However, patients with preoperative severe OSA and hypertension need careful management of their elevated BP despite surgical treatment.

The successful management of respiratory complications with long-term, low-dose macrolide administration in pediatric heart transplant recipients

We report three pediatric heart transplant (HTx) patients whose respiratory symptoms were successfully controlled with long-term, low-dose macrolide administration (clarithromycin: CAM; approximately 2.5 mg/kg bid). The first case was an 18-year-old boy who underwent HTx at the age of three for dilated cardiomyopathy (DCM). Beginning at age 5, he had repeated fevers and respiratory symptoms. He was diagnosed with chronic sinusitis at age 11 and sinobronchial syndrome with mild bronchiectasis at age 14. Administration of long-term, low-dose CAM and otolaryngeal topical therapy led to significant improvement of his symptoms. The second case was a 7-year-old boy who underwent HTx for DCM at age one. Starting at age 4, he had repeated fevers and cough due to atelectasis and pneumonia. As antibiotics and respiratory physical therapy proved ineffective, he received long-term, low-dose CAM, resulting in successful control of his atelectasis and recurrent pneumonia. The third case was a 13-year-old boy who underwent HTx at age 6 for DCM. He had chronic sinusitis starting at age 7, and was diagnosed with obstructive sleep apnea syndrome at age 10. Adenotonsillectomy and continuous positive airway pressure support therapy were indicated. At age 13, long-term, lowdose CAM administration was started following mycoplasma infection. In all three cases, the levels of calcineurin inhibitors (cyclosporine and tacrolimus) and everolimus were kept in the optimal range with careful drug monitoring. Longterm, low-dose macrolide administration effectively prevents and treats respiratory complications in pediatric HTx patients as long as attention is paid to potential drug interactions.

Quality of life after adenotonsillectomy for children with sleep-disordered breathing: a linear mixed model analysis

OBJECTIVE

To study changes in quality of life (QoL) after adenotonsillectomy (T&A) in children with sleep-disordered breathing (SDB), and to elucidate discrepancies in QoL improvements after T&A in children of different gender, age, adiposity status, and disease severity.

MATERIALS AND METHODS

Children aged 2-18 years were recruited. All children had SDB-related symptoms and underwent preoperative full-night polysomnography (PSG). Caregivers completed the first obstructive sleep apnea 18-items questionnaire (OSA-18) prior to T&A and the second OSA-18 survey within 3 months after surgery. Disease severity was defined as primary snoring (apnea/hypopnea index, AHI < 1), mild obstructive sleep apnea (OSA) (5 > AHI ≥ 1), and moderate-to-severe OSA (AHI ≥ 5). Discrepancies in OSA-18 score changes after T&A for different groups were assessed using the linear mixed model.

RESULTS

In total, 144 children were enrolled (mean age, 7.0 ± 3.6 years; 76% boy). The OSA-18 total score changes after surgery were not significantly different by gender (boys vs. girls), age group (≥ 6 years vs. < 6 years), or adiposity (obese vs. non-obese). The OSA-18 total score changes after surgery differed by disease severity (primary snoring vs. moderate-to-severe OSA, P = 0.004; mild OSA vs. moderate-to-severe OSA, P = 0.003). Children with moderate-to-severe OSA had greater improvement in OSA-18 total score after surgery than those with mild OSA or primary snoring.

CONCLUSIONS

Children with SDB had QoL improvement after T&A, as documented by OSA-18 score changes. The QoL improvement after T&A for SDB children increased as disease severity increased, and the improvement was not affected by gender, age, or adiposity.

Polymorphisms in nitric oxide synthase and endothelin genes among children with obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is associated with adverse and interdependent cognitive and cardiovascular consequences. Increasing evidence suggests that nitric oxide synthase (NOS) and endothelin family (EDN) genes underlie mechanistic aspects of OSA-associated morbidities. We aimed to identify single nucleotide polymorphisms (SNPs) in the NOS family (3 isoforms), and EDN family (3 isoforms) to identify potential associations of these SNPs in children with OSA.

Methods

A pediatric community cohort (ages 5–10 years) enriched for snoring underwent overnight polysomnographic (NPSG) and a fasting morning blood draw. The diagnostic criteria for OSA were an obstructive apnea-hypopnea Index (AHI) >2/h total sleep time (TST), snoring during the night, and a nadir oxyhemoglobin saturation <92%. Control children were defined as non-snoring children with AHI <2/h TST (NOSA). Endothelial function was assessed using a modified post-occlusive hyperemic test. The time to peak reperfusion (Tmax) was considered as the indicator for normal endothelial function (NEF; Tmax<45 sec), or ED (Tmax≥45 sec). Genomic DNA from peripheral blood was extracted and allelic frequencies were assessed for, NOS1 (209 SNPs), NOS2 (122 SNPs), NOS3 (50 SNPs), EDN1 (43 SNPs), EDN2 (48 SNPs), EDN3 (14 SNPs), endothelin receptor A, EDNRA, (27 SNPs), and endothelin receptor B, EDNRB (23 SNPs) using a custom SNPs array. The relative frequencies of NOS-1,-2, and −3, and EDN-1,-2,-3,-EDNRA, and-EDNRB genotypes were evaluated in 608 subjects [128 with OSA, and 480 without OSA (NOSA)]. Furthermore, subjects with OSA were divided into 2 subgroups: OSA with normal endothelial function (OSA-NEF), and OSA with endothelial dysfunction (OSA-ED). Linkage disequilibrium was analyzed using Haploview version 4.2 software.

Results

For NOSA vs. OSA groups, 15 differentially distributed SNPs for NOS1 gene, and 1 SNP for NOS3 emerged, while 4 SNPs for EDN1 and 1 SNP for both EDN2 and EDN3 were identified. However, in the smaller sub-group for whom endothelial function was available, none of the significant SNPs was retained due to lack of statistical power.

Conclusions

Differences in the distribution of polymorphisms among NOS and EDN gene families suggest that these SNPs could play a contributory role in the pathophysiology and risk of OSA-induced cardiovascular morbidity. Thus, analysis of genotype-phenotype interactions in children with OSA may assist in the formulation of categorical risk estimates.

Nocturnal autonomic function in preschool children with sleep-disordered breathing

BACKGROUND

Obstructive sleep apnea (OSA) is associated with autonomic dysfunction in adults and school-aged children; however, this association has not been investigated in preschool children. We aimed to analyze heart rate variability (HRV) and catecholamine levels in preschool children with OSA.

METHODS

One hundred and forty-two snoring children aged 3-5years and 38 nonsnoring control group children underwent overnight polysomnography (PSG). Nocturnal urinary catecholamines were measured in 120 children. Children were grouped according to their obstructive apnea-hypopnea index (OAHI) (control [no snoring], OAHI⩽1event/h; primary snoring, OAHI⩽1event/h; mild OSA OAHI>1⩽5events/h; moderate to severe [MS] OSA, OAHI>5events/h). The HRV parameters for each child were averaged during rapid eye movement (REM) and non-REM (NREM) sleep.

RESULTS

During stable sleep, low-frequency (LF) HRV was similar between groups. High-frequency (HF) HRV was higher in the MS OSA group compared with the control group during all sleep stages (NREM sleep stages 1 and 2 [NREM1/2], 4234±523ms(2) vs 2604±457ms(2); NREM sleep stages 3 and 4 [NREM3/4], 4152±741ms(2) vs 3035±647ms(2); REM, 1836±255ms(2) vs 1456±292ms(2); P<.01 for all). The LF/HF ratio was lower in the MS OSA group compared with the control group (NREM1/2, 0.4±0.06 vs 0.7±0.05; NREM3/4, 0.3±0.06 vs 0.4±0.05; REM, 0.8±0.1 vs 1.3±0.1; P<.01 for all). Catecholamine levels were not different between groups.

CONCLUSIONS

In preschool children, OSA is associated with altered HRV, largely due to the HF fluctuations in heart rate (HR) which occur during respiratory events and are still evident during stable sleep. The preschool age may represent a window of opportunity for treatment of OSA before the onset of the severe autonomic dysfunction associated with OSA in adults and older children.

Sleep-disordered breathing and C-reactive protein in obese children and adolescents

PURPOSE

Sleep-disordered breathing (SDB) is common among overweight and obese children. It is a risk factor for several health complications, including cardiovascular disease. Inflammatory processes leading to endothelial dysfunction are a possible mechanism linking SDB and cardiovascular disease. Elevated C-reactive protein (CRP) is a risk factor for cardiovascular disease and is independently correlated with obstructive sleep apnea syndrome (OSAS) in adults. Our goal is to evaluate the relationship between CRP and OSAS in overweight and obese children and adolescents.

METHODS

One hundred and twenty children were prospectively studied (85 without OSAS, 20 mild OSAS, 15 moderate-to-severe OSAS). All subjects underwent polysomnography, and a blood sample was taken to determine CRP levels.

RESULTS

No significant differences were found in CRP between subjects with or without OSAS, and no correlations were found between CRP and OSAS severity, despite the relationship between CRP and BMI (r = 0.21, p = 0.015) and between CRP and fat mass (r = 0.31, p < 0.001).

CONCLUSION

These results suggest that CRP levels are correlated with the level of obesity but are not influenced by SDB in obese children and adolescents; hence, this in contrast to that in adult population.

Characterization of the acute pulse transit time response to obstructive apneas and hypopneas in preschool children with sleep-disordered breathing

BACKGROUND

Surges in heart rate (HR) and blood pressure (BP) at apnea termination contribute to the hypertension seen in obstructive sleep apnea (OSA). Because childhood OSA prevalence peaks in the preschool years, we aimed to characterize the cardiovascular response to obstructive events in preschool-aged children.

METHODS

Clinically referred children aged 3-5 years were grouped by obstructive apnea-hypopnea index (OAHI) into the following: primary snoring (PS) (OAHI≤1 event/h [n=21]), mild OSA (OAHI>1-≤5 [n=32]), and moderate to severe (MS) OSA (OAHI>5 [n=28]). Beat-to-beat pulse transit time (PTT), an inverse continuous indicator of BP changes, and HR were averaged during the two halves (early and late) and during the peak after (post) each obstructive event and were expressed as percentage change from late- to post-event.

RESULTS

We analyzed 422 events consisting of 55 apneas and 367 hypopneas. A significant post-event increase in HR and fall in PTT occurred in all severity groups (P<.05 for all). A greater response was associated with OSA, nonrapid eye movement sleep (NREM), cortical arousal, hypopneas, and oxygen desaturation (P<.05 for all).

CONCLUSIONS

Obstructive events elicit acute cardiovascular changes in preschool children. Such circulatory perturbations have been implicated in the development of hypertension, and our findings complement previous studies to suggest a cumulative impact of snoring on the cardiovascular system from childhood into adulthood.

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.