Urinary neurotransmitters are selectively altered in children with obstructive sleep apnea and predict cognitive morbidity

Sympathetic nervous system activity is associated with choroidal thickness and axial length in school-aged children

BACKGROUND/AIMS

We aim to explore the effect of sympathetic nervous system (SNS) on choroid thickness (ChT) and axial length (AL).

METHODS

Students of grade 2 and 3 from a primary school were included and followed for 1 year. Visual acuity, refraction, AL and ChT were measured. Morning urine samples were collected for determining SNS activity by analysing concentrations of epinephrine, norepinephrine and dopamine using the liquid chromatography-tandem mass spectrometry. The most important factor (factor 1) was calculated using factor analysis to comprehensively indicate the SNS activity.

RESULTS

A total of 273 students were included, with an average age of 7.77±0.69 years, and 150 (54.95%) were boys. Every 1 µg/L increase in epinephrine is associated with 1.60 µm (95% CI 0.30 to 2.90, p=0.02) decrease in average ChT. Every 1 µg/L increase in norepinephrine is associated with 0.53 µm (95% CI 0.08 to 0.98, p=0.02) decrease in the ChT in inner-superior region. The factor 1 was negatively correlated with the ChT in the superior regions. Every 1 µg/L increase in norepinephrine was associated with 0.002 mm (95% CI 0.0004 to 0.004, p=0.016) quicker AL elongation. The factor 1 was positively correlated with AL elongation (coefficient=0.037, 95% CI 0.005 to 0.070, p=0.023).

CONCLUSIONS

We hypothesised that chronic stress characterised by elevated level of the SNS, was associated with significant increase in AL elongation, probably through thinning of the choroid.

Mental stress objective screening for workers using urinary neurotransmitters

BACKGROUND

Almost 10% of the population develop depression or anxiety disorder during their lifetime. Considering that people who are exposed to high stress are more likely to develop mental disorders, it is important to detect and remove mental stress before depression or anxiety disorder develops. We aimed to develop an objective screening test that quantifies mental stress in workers so that they can recognize and remove it before the disorder develops.

METHODS

We obtained urine specimens from 100 healthy volunteers (49 men and 51 women; age = 48.2 ± 10.8 years) after they received medical checks and answered the Brief Job Stress Questionnaire (BJSQ). Participants were divided into high- and low- stress groups according to their total BJSQ scores. We further analyzed six urinary neurotransmitters (dopamine, serotonin, 5-hydoroxyindoleacetic acid, gamma-aminobutyric acid, homovanillic acid, and vanillylmandelic acid) using liquid chromatography-mass spectrometry to compare their levels between the two groups.

RESULTS

We obtained the concentrations of the six analytes from 100 examinees and revealed that the levels of urinary dopamine (p = 0.0042) and homovanillic acid (p = 0.020) were significantly lower in the high-stress group than those in the low-stress group. No biases were observed between the two groups in 36 laboratory items. The stress index generated from the six neurotransmitter concentrations recognized high-stress group significantly. Moreover, we discovered that the level of each urinary neurotransmitter changed depending on various stress factors, such as dissatisfaction, physical fatigue, stomach and intestine problems, poor appetite, poor working environments, sleep disturbance, isolation, worry, or insecurity.

CONCLUSION

We revealed that urinary neurotransmitters could be a promising indicator to determine underlying mental stress. This study provides clues for scientists to develop a screening test not only for workers but also for patients with depression.

Diagnosis of Paediatric Obstructive Sleep-Disordered Breathing beyond Polysomnography

Obstructive sleep-disordered breathing (SDB) has significant impacts on health, and therefore, a timely and accurate diagnosis is crucial for effective management and intervention. This narrative review provides an overview of the current approaches utilised in the diagnosis of SDB in children. Diagnostic methods for SDB in children involve a combination of clinical assessment, medical history evaluation, questionnaires, and objective measurements. Polysomnography (PSG) is the diagnostic gold standard. It records activity of brain and tibial and submental muscles, heart rhythm, eye movements, oximetry, oronasal airflow, abdominal and chest movements, body position. Despite its accuracy, it is a time-consuming and expensive tool. Respiratory polygraphy instead monitors cardiorespiratory function without simultaneously assessing sleep and wakefulness; it is more affordable than PSG, but few paediatric studies compare these techniques and there is optional recommendation in children. Nocturnal oximetry is a simple and accessible exam that has high predictive value only for children at high risk. The daytime nap PSG, despite the advantage of shorter duration and lower costs, is not accurate for predicting SDB. Few paediatric data support the use of home testing during sleep. Finally, laboratory biomarkers and radiological findings are potentially useful hallmarks of SDB, but further investigations are needed to standardise their use in clinical practice.

Investigating the Relationship between Obstructive Sleep Apnoea, Inflammation and Cardio-Metabolic Diseases

Obstructive sleep apnoea (OSA) is a prevalent underdiagnosed disorder whose incidence increases with age and weight. Uniquely characterised by frequent breathing interruptions during sleep-known as intermittent hypoxia (IH)-OSA disrupts the circadian rhythm. Patients with OSA have repeated episodes of hypoxia and reoxygenation, leading to systemic consequences. OSA consequences range from apparent symptoms like excessive daytime sleepiness, neurocognitive deterioration and decreased quality of life to pathological complications characterised by elevated biomarkers linked to endocrine-metabolic and cardiovascular changes. OSA is a well-recognized risk factor for cardiovascular and cerebrovascular diseases. Furthermore, OSA is linked to other conditions that worsen cardiovascular outcomes, such as obesity. The relationship between OSA and obesity is complex and reciprocal, involving interaction between biological and lifestyle factors. The pathogenesis of both OSA and obesity involve oxidative stress, inflammation and metabolic dysregulation. The current medical practice uses continuous positive airway pressure (CPAP) as the gold standard tool to manage OSA. It has been shown to improve symptoms and cardiac function, reduce cardiovascular risk and normalise biomarkers. Nonetheless, a full understanding of the factors involved in the deleterious effects of OSA and the best methods to eliminate their occurrence are still poorly understood. In this review, we present the factors and evidence linking OSA to increased risk of cardiovascular conditions.

Level of urinary catecholamine in children with Sleep Disordered Breathing: A systematic review and meta-analysis

OBJECTIVE

To compare the levels of different urinary catecholamines amongst paediatric patients with and without sleep-disordered breathing (SDB).

METHODS

Literature searches were conducted on PubMed and EMBASE until 25/06/2022. Inclusion criteria were original human studies, English language, paediatric subjects diagnosed with SDB/obstructive sleep apnoea (OSA). The quality of studies was assessed by the Newcastle-Ottawa Quality Assessment (NOSGEN). The registered number of this study on the International Prospective Register of Systematic Reviews (PROSPERO) is CRD42022332939. The main outcome measured was standardised mean difference (SMD) of urinary catecholamine between subjects with and without SDB, between those with and without OSA, and also between subjects with mild OSA and those with moderate/ severe OSA. Sensitivity analyses were performed to avoid bias.

RESULTS

9 studies (8 cross-sectional and 1 cohort study) with a total of 838 subjects, were included in the quantitative analysis. Urine level of noradrenaline was higher in patients with SDB, which included primary snoring (PS), when compared to controls: SMD = 0.86 (95%CI=0.32-1.41; I²=85%, P=0.002). The levels of urinary noradrenaline and adrenaline were higher in children with OSA when compared to controls: SMD = 1.45 (95%CI=0.91-2.00; I²=75%, P < 0.001); SMD = 1.84 (0.00-3.67; I²=97%, P=0.05). Urine level of noradrenaline was higher in subjects with moderate/severe OSA compared to the mild OSA: SMD = 0.55 (95%CI=0.10-1.00; I²=0%, P=0.02). Urinary dopamine was not associated with SDB regardless of severity.

CONCLUSIONS

Urinary noradrenaline was higher in all patients with SDB. Subjects with OSA, a more severe form of SDB, had higher urine levels of noradrenaline and adrenaline. Hence, noradrenaline and adrenaline may be markers of sympathetic overtone in patients with SDB and could potentially act as surrogate markers for SDB complications. Further studies are needed to assess this association.

Screening of plasma exosomal lncRNAs to identify potential biomarkers for obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is highly prevalent, but frequently undiagnosed. The existing biomarkers of OSA are relatively insensitive and inaccurate. Long non-coding RNAs (lncRNAs) have no protein-coding ability but have a role in regulating gene expression. They are stably expressed in exosomes, easily and rapidly measurable. Changes in expression of exosomal lncRNAs can be useful for disease diagnoses. However, there are few reports on the association of exosomal lncRNAs with OSA. We aimed to investigate the exosomal lncRNA profiles to establish the differences between non-OSA, OSA with or without hypertension (HTN) and serve as a potential diagnostic biomarker.

Methods

This diagnostic test included 63 participants: [normal control (NC) =25], (OSA =23), and (HTN-OSA =15). Expression profiling of lncRNAs in isolated exosomes was performed through high-throughput sequencing in 9 participants. Subsequently, OSA/HTN-OSA related lncRNAs were selected for validation by droplet digital polymerase chain reaction (ddPCR), receiver operating characteristic (ROC) curves were used to determine the diagnostic value. The reliabilities of the screened gene were further validated in another independent cohort: (NC =10), (OSA mild =10), (OSA moderate =11), and (OSA severe =10), the correlation between clinical features and its expression was analyzed. The MiRanda software was used to predict the binding sites of interaction between microRNA (miRNA) and target genes regulated by screened lncRNA.

Results

We identified the differentially expressed lncRNAs and mRNAs in plasma exosomes of the NC, OSA, HTN-OSA groups. Most pathways enriched in differentially expressed lncRNAs and mRNAs had previously been linked to OSA. Among them, ENST00000592016 enables discrimination between NC and OSA individuals [area under curve (AUC) =0.846, 95% confidence interval (CI): 0.72–0.97]. The severity of OSA was associated with changes in the ENST00000592016 expression. Furthermore, ENST00000592016 affected the PI3K-Akt, MAPK, and TNF pathways by regulating miRNA expressions.

Conclusions

This is the first report about differential expression of lncRNA in OSA and HTN-OSA exosomes. ENST00000592016 enables discrimination between NC and OSA individuals. This work enabled characterization of OSA and provided the preliminary work for the study of biomarker of OSA.

Intermittent Hypoxia Interferes with Autocrine Effects of GABA on Insulin Secretion in Postnatal Rodents—Implications for Pediatric Obstructive Sleep Apnea

Gamma-amino butyric acid (GABA) is well known to help elevate pancreatic β cell vitality and insulin levels in blood. GABA works via a coupling with GABA receptors; thus, the concentration of GABA_A receptors on the plasma membrane of β cells appears to be critical for insulin regulation. Various medical conditions, such as pediatric and adult obstructive sleep apnea (OSA), show high levels of Type 2 diabetes; such patients also are exposed to intermittent hypoxia (IH), which modifies the GABA levels. To evaluate the potential therapeutic roles of GABA for diabetic patients with OSA, we studied the interactions of IH with GABA and GABA_A receptors in young rats. Using rat pups and primary pancreatic islets, we evaluated the roles of GABA in insulin secretion. We show that GABA effectively increased the insulin secretion of pancreatic islets under normal ambient oxygen levels, as well as in culture medium with a glucose level of 2 mM. GABA also increased islet insulin secretion conditioned under IH in a 16 mM glucose medium. When islets were IH-treated, insulin secretion decreased due to lower intracellular chloride levels in accordance with the increased KCC2 levels. The results show that IH challenges down-regulate the GABA_A receptor levels in pancreatic islets, which decreases GABA–GABA_A receptor coupling action, as well as membrane depolarization for insulin secretion. The findings have the potential to suggest novel interventions for insulin regulation during IH of disordered breathing, including OSA.

Neurocognitive Consequences in Children with Sleep Disordered Breathing: Who Is at Risk?

Sleep-disordered breathing (SDB) is a prevalent disease in children characterized by snoring and narrowing of the upper airway leading to gas exchange abnormalities during sleep as well as sleep fragmentation. SDB has been consistently associated with problematic behaviors and adverse neurocognitive consequences in children but causality and determinants of susceptibility remain incompletely defined. Since the 1990s several studies have enlightened these associations and consistently reported poorer academic performance, lower scores on neurocognitive tests, and behavioral abnormalities in children suffering from SDB. However, not all children with SDB develop such consequences, and severity of SDB based on standard diagnostic indices has often failed to discriminate among those children with or without neurocognitive risk. Accordingly, a search for discovery of markers and clinically useful tools that can detect those children at risk for developing cognitive and behavioral deficits has been ongoing. Here, we review the advances in this field and the search for possible detection approaches and unique phenotypes of children with SDB who are at greater risk of developing neurocognitive consequences.

Urinary Aromatic Amino Acid Metabolites Associated With Postoperative Emergence Agitation in Paediatric Patients After General Anaesthesia: Urine Metabolomics Study

Background: Emergence agitation (EA) is very common in paediatric patients during recovery from general anaesthesia, but underlying mechanisms remain unknown. This prospective study was designed to profile preoperative urine metabolites and identify potential biomarkers that can predict the occurrence of EA.

Methods: A total of 224 patients were screened for recruitment; of those, preoperative morning urine samples from 33 paediatric patients with EA and 33 non-EA gender- and age-matched patients after being given sevoflurane general anaesthesia were analysed by ultra-high-performance liquid chromatography (UHPLC) coupled with a Q Exactive Plus mass spectrometer. Univariate analysis and orthogonal projection to latent structures squares-discriminant analysis (OPLS-DA) were used to analyse these metabolites. The least absolute shrinkage and selection operator (LASSO) regression was used to identify predictive variables. The predictive model was evaluated through the receiver operating characteristic (ROC) analysis and then further assessed with 10-fold cross-validation.

Results: Seventy-seven patients completed the study, of which 33 (42.9%) patients developed EA. EA and non-EA patients had many differences in preoperative urine metabolic profiling. Sixteen metabolites including nine aromatic amino acid metabolites, acylcarnitines, pyridoxamine, porphobilinogen, 7-methylxanthine, and 5′-methylthioadenosine were found associated with an increased risk of EA, and they all exhibited higher levels in the EA group than in the non-EA group. The main metabolic pathways involved in these metabolic changes included phenylalanine, tyrosine and tryptophan metabolisms. Among these potential biomarkers, L-tyrosine had the best predictive value with an odds ratio (OR) (95% CI) of 5.27 (2.20–12.63) and the AUC value of 0.81 (0.70–0.91) and was robust with internal 10-fold cross-validation.

Conclusion: Urinary aromatic amino acid metabolites are closely associated with EA in paediatric patients, and further validation with larger cohorts and mechanistic studies is needed.

Clinical Trial Registration:clinicaltrials.gov, identifier NCT04807998

Catecholamines and children obstructive sleep apnea: a systematic review

INTRODUCTION

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder in children and is characterized by recurrent total or partial upper airway collapse episodes during sleep. OSA is associated with cardiovascular, metabolic and neurobehavioural complications related to sympathetic nervous system (SNS) activation. A key role in originating these complications and in underlying pathophysiologic mechanisms can be attributed to altered catecholamines (CAs) metabolism.

METHODS

A systematic review was performed according to the PRISMA Statement guidelines for research studies correlating OSA in children with catecholamines.

RESULTS

Only 13 studies out of 151 reports were included in the review. Most studies (9 out of 13) showed increased secretion for some catecholamines in patients with a sleep-related breathing disorder or OSA compared to a control group or post treatment control group.

CONCLUSION

OSA can activate the sympathetic nervous system (SNS) and increase catecholamines (CAs) production, perhaps contributing to increased morbidity. However, underlying pathophysiologic mechanisms remain still unclear.

Cyclic alternating pattern in children with obstructive sleep apnea and its relationship with adenotonsillectomy, behavior, cognition, and quality of life

STUDY OBJECTIVES

To determine in children with obstructive sleep apnea (OSA) the effect of adenotonsillectomy (AT) on the cyclic alternating pattern (CAP) and the relationship between CAP and behavioral, cognitive, and quality-of-life measures.

METHODS

CAP parameters were analyzed in 365 overnight polysomnographic recordings of children with mild-to-moderate OSA enrolled in the Childhood Adenotonsillectomy Trial (CHAT), randomized to either early AT (eAT) or watchful waiting with supportive care (WWSC). We also analyzed CAP in a subgroup of 72 children with moderate OSA (apnea-hypopnea index > 10) that were part of the CHAT sample. Causal mediation analysis was performed to determine the independent effect of changes in CAP on selected outcome measures.

RESULTS

At baseline, a higher number of A1 phases per hour of sleep was significantly associated with worse behavioral functioning (caregiver Behavior Rating Inventory of Executive Function (BRIEF) Global Executive Composite (GEC): ρ = 0.24, p = 0.042; caregiver Conners' Rating Scale Global Index: ρ = 0.25, p = 0.036) and lower quality of life (OSA-18: ρ = 0.27, p = 0.022; PedsQL: ρ = -0.29, p = 0.015) in the subgroup of children with moderate OSA, but not across the entire sample. At 7-months follow-up, changes in CAP parameters were comparable between the eAT and WWSC arms. CAP changes did not account for significant proportions of variations in behavioral, cognitive, and quality-of-life performance measures at follow-up.

CONCLUSIONS

We show a significant association between the frequency of slow, high-amplitude waves with behavioral functioning, as well as the quality of life in children with moderate OSA. Early AT in children with mild-to-moderate OSA does not alter the microstructure of nonrapid eye movement sleep compared with watchful waiting after an approximately 7-month period of follow-up.

CLINICAL TRIAL

The study "A Randomized Controlled Study of Adenotonsillectomy for Children With Obstructive Sleep Apnea Syndrome" was registered at Clinicaltrials.gov (#NCT00560859).

Journey towards a personalised medicine approach for OSA: Can a similar approach to adult OSA be applied to paediatric OSA?

The concept of personalised medicine is likely to revolutionise the treatment of adult obstructive sleep apnoea as a result of recent advances in the understanding of disease heterogeneity by identifying clinical phenotypes, pathophysiological endotypes, biomarkers and treatable traits. Children with the condition show a similar level of heterogeneity and paediatric obstructive sleep apnoea would also benefit from a more targeted approach to diagnosis and management. This review aims to summarise the adult literature on the phenotypes and endotypes of obstructive sleep apnoea and assess whether a similar approach may also be suitable to guide the development of new diagnostic and management approaches for paediatric obstructive sleep apnoea.

Elevated serum calprotectin as an inflammatory marker in obstructive sleep apnea

OBJECTIVE

To investigate the serum calprotectin (SCal) levels and neutrophil/lymphocyte ratio (NLR) values in patients with obstructive sleep apnea (OSA).

METHODS

Sixty-seven OSA patients and 46 healthy volunteers without any sleep disorders were included in the study. The patient group was divided into three subgroups according to the severity of OSA. The SCal levels and NLR values were compared among subgroups and between the experimental and control groups.

RESULTS

The mean SCal level and NLR value were higher in the study group than in the control group (p = 0.002 and p = 0.001, respectively). The SCal levels were significantly higher in patients with severe OSA than in those with moderate and mild OSA (p = 0.004 and p = 0.001, respectively).

DISCUSSION

Unlike NLR, the SCal level may inform the severity of OSA and could be used as an indicator for OSA.

Preoperative identification of children at high risk of obstructive sleep apnea

Obstructive sleep apnea is a common childhood disorder which can lead to serious health problems if left untreated. Enlarged adenoid and tonsils are the commonest causes, and adenotonsillectomy is the recommended first line of treatment. Obstructive sleep apnea poses as an anesthetic challenge, and it is a well-known risk factor for perioperative adverse events. The presence and severity of an obstructive sleep apnea diagnosis will influence anesthesia, pain management, and level of monitoring in recovery period. Preoperative obstructive sleep apnea assessment is necessary, and anesthetists are ideally placed to do so. Currently, there is no standardized approach to the best method of preoperative screening for obstructive sleep apnea. Focused history, clinical assessments, and knowledge regarding the strengths and limitations of available obstructive sleep apnea assessment tools will help recognize a child with obstructive sleep apnea in the preoperative setting.

Guidelines of the French Society of Otorhinolaryngology. Role of the ENT specialist in the diagnosis of obstructive sleep apnea-hypopnea syndrome (OSAHS) in children. Part 2: Diagnostic investigations apart from sleep studies

OBJECTIVES

To present the 2017 Clinical Practice Guidelines of the French Society of Otorhinolaryngology concerning the role of the ENT specialist in the diagnosis of pediatric obstructive sleep apnea-hypopnea syndrome. This manuscript specifically focuses on diagnostic investigations apart from sleep studies.

METHODS

A multidisciplinary work-group drew up a first version of the guidelines, graded according to level of evidence following the GRADE grading system. The final version was obtained by including the suggestions and comments from the editorial group.

RESULTS

At the end of the process, guidelines were established and graded regarding diagnostic investigations apart from sleep studies, in particular respiratory functional tests, biological markers, and morphologic assessment under induced sleep (drug-induced sleep endoscopy (DISE) and cine-MRI).

Related biomarkers of neurocognitive impairment in children with obstructive sleep apnea

OBJECTIVES

Different experiment approaches have demonstrated that children with obstructive sleep apnea (OSA) exhibit neurocognitive and behavioral deficits. This review summarized the potential biomarkers of OSA-associated neurocognitive impairment in children.

METHODS

A scoping review of studies on children with OSA that evaluated the potential value of different markers in identifying neurocognitive impairment was undertaken. Additionally, the biomarkers were categorized according to the different research methods, including brain imaging studies, serological indicators and urine markers.

RESULTS

Majority of the studies that evaluated blood biomarkers, plasma insulin growth factor-1 (IGF-1) and Alzheimer's disease (AD)-related biomarkers appeared to exhibit a favorable profile, and could discriminate between OSA children with or without neurocognitive impairments. Brain imaging studies and urinary neurotransmitters could also be helpful for screening OSA cognitive morbidity in children.

CONCLUSION

Due to limited research methods available in children, the cognitive susceptibility of children with OSA has been rarely studied. The main reason for this may be the limited research methods in children. Numerous study populations of children and complex psychological tests are required, which involve major labor and costs.Multi-center prospective studies are needed to identify suitable biomarkers for the timely prediction and effective intervention to prevent neurocognitive impairment in children with OSA and to explore further opportunities in this arena.

DNA Methylation in Pediatric Obstructive Sleep Apnea: An Overview of Preliminary Findings

Obstructive sleep apnea (OSA) is characterized by phenotypic variations, which can be partly attributed to specific gene polymorphisms. Recent studies have focused on the role of epigenetic mechanisms in order to permit a more precise perception about clinical phenotyping and targeted therapies. The aim of this review was to synthesize the current state of knowledge on the relation between DNA methylation patterns and the development of pediatric OSA, in light of the apparent limited literature in the field. We performed an electronic search in PubMed, EMBASE, and Google Scholar databases, including all types of articles written in English until January 2017. Literature was apparently scarce; only 2 studies on pediatric populations and 3 animal studies were identified. Forkhead Box P3 (FOXP3) DNA methylation levels were associated with inflammatory biomarkers and serum lipids. Hypermethylation of the core promoter region of endothelial Nitric Oxide Synthase (eNOS) gene in OSA children were related with decreased eNOS expression. Additionally, increased expression of genes encoding pro-oxidant enzymes and decreased expression of genes encoding anti-oxidant enzymes suggested that disturbances in oxygen homeostasis throughout neonatal period predetermined increased hypoxic sensing in adulthood. In conclusion, epigenetic modifications may be crucial in pediatric sleep disorders to enable in-depth understanding of genotype-phenotype interactions and lead to risk assessment. Epigenome-wide association studies are urgently needed to validate certain epigenetic alterations as reliable, novel biomarkers for the molecular prognosis and diagnosis of OSA patients with high risk of end-organ morbidity.

A predictive model for obstructive sleep apnea and Down syndrome

Obstructive sleep apnea (OSA) occurs frequently in people with Down syndrome (DS) with reported prevalences ranging between 55% and 97%, compared to 1-4% in the neurotypical pediatric population. Sleep studies are often uncomfortable, costly, and poorly tolerated by individuals with DS. The objective of this study was to construct a tool to identify individuals with DS unlikely to have moderate or severe sleep OSA and in whom sleep studies might offer little benefit. An observational, prospective cohort study was performed in an outpatient clinic and overnight sleep study center with 130 DS patients, ages 3-24 years. Exclusion criteria included previous adenoid and/or tonsil removal, a sleep study within the past 6 months, or being treated for apnea with continuous positive airway pressure. This study involved a physical examination/medical history, lateral cephalogram, 3D photograph, validated sleep questionnaires, an overnight polysomnogram, and urine samples. The main outcome measure was the apnea-hypopnea index. Using a Logic Learning Machine, the best model had a cross-validated negative predictive value of 73% for mild obstructive sleep apnea and 90% for moderate or severe obstructive sleep apnea; positive predictive values were 55% and 25%, respectively. The model included variables from survey questions, medication history, anthropometric measurements, vital signs, patient's age, and physical examination findings. With simple procedures that can be collected at minimal cost, the proposed model could predict which patients with DS were unlikely to have moderate to severe obstructive sleep apnea and thus may not need a diagnostic sleep study.

Urinary biomarkers and obstructive sleep apnea in patients with Down syndrome

STUDY OBJECTIVES

The study aimed to compare urinary biomarkers in patients with Down syndrome (DS) with and without obstructive sleep apnea (OSA) to those of age- and sex-matched neurotypically developing healthy controls (HC). We further investigated whether we could predict OSA in patients with DS using these biomarkers.

METHODS

Urine samples were collected from 58 patients with DS the night before or the morning after their scheduled overnight polysomnogram or both, of whom 47 could be age- and sex-matched to a sample of 43 HC. Concentrations of 12 neurotransmitters were determined by enzyme-linked immunosorbent assay. Log-transformed creatinine-corrected assay levels were normalized. Normalized z-scores were compared between patients with DS vs. HC, between patients with DS with vs. without OSA, and to derive composite models to predict OSA.

RESULTS

Most night-sampled urinary biomarkers were elevated among patients with DS relative to matched HC. No urinary biomarker levels differed between patients with DS with vs. without OSA. A combination of four urinary biomarkers predicted AHI > 1 with a positive predictive value of 90% and a negative predictive value of 68%.

CONCLUSIONS

Having DS, even in the absence of concurrent OSA, is associated with a different urinary biomarker profile when compared to that of HC. Therefore, while urinary biomarkers may be predictive of OSA in the general pediatric population, a different approach is needed in interpreting urinary biomarker assays in patients with DS. Certain biomarkers also seem promising to be predictive of OSA in patients with DS. No clinical trial was indicated in the undertaking of this work.

When and why to treat the child who snores?

Obstructive sleep-disordered breathing (SDB) can result in cardiovascular and neurocognitive morbidity as well as adversely affect behavior, growth, quality of life, and nocturnal continence. This article summarizes the latest evidence regarding the morbidity related to obstructive SDB, commenting on the impact of severity of obstruction, that is, the difference in effects seen of moderate to severe obstructive sleep apnea syndrome (OSAS) compared to those of mild OSAS or primary snoring. The impact of therapy is discussed, focusing on which children are likely to benefit from treatment interventions; namely those with moderate or severe OSAS irrespective of the presence of morbidity, children with mild OSAS with associated morbidity or predictors of SDB persistence such as obesity, and children with complex conditions accompanied by upper airway obstruction like craniosynostosis and Prader-Willi syndrome. The co-existing conditions which may improve when treatment for obstructive SDB is offered are reviewed, while the clinical parameters associated with spontaneous improvement or resolution of obstructive SDB are discussed. The intention being to enable clinicians to make informed decisions on who should be treated, when and why. Pediatr Pulmonol. 2017;52:399-412. © 2016 Wiley Periodicals, Inc.

Pediatric OSA Syndrome Morbidity Biomarkers: The Hunt Is Finally On!

Since initial reports 40 years ago on pediatric OSA syndrome (OSAS) as a distinct and prevalent clinical entity, substantial advances have occurred in the delineation of diagnostic and treatment approaches. However, despite emerging and compelling evidence that OSAS increases the risk for cognitive, cardiovascular, and metabolic end-organ morbidities, routine assessment of such morbidities is seldom conducted in clinical practice. One of the major reasons for such discrepancies resides in the relatively labor-intensive and onerous steps that would be required to detect the presence of any of such morbidities, further adding to the already elevated cost of diagnosing the disorder. To circumvent these obstacles, the search for biomarker signatures of pediatric OSA and its cognitive and cardiometabolic consequences was launched, and considerable progress has occurred since then. Here, we review the current evidence for the presence of morbidity-related biomarkers among children with OSAS, and explore future opportunities in this promising arena.

Pediatric Home Sleep Apnea Testing: Slowly Getting There!

Pediatric OSA can result in significant neurocognitive, behavioral, cardiovascular, and metabolic morbidities. Prompt diagnosis and treatment are, therefore, of paramount importance. The current gold standard for diagnosis of OSA in children is in-laboratory polysomnography (PSG). Home sleep apnea testing has been considered as an alternative as it is potentially more cost effective, convenient, and accessible. This review concentrates mainly on the use of type 2 and 3 portable monitoring devices. The current evidence on the feasibility and diagnostic accuracy of home testing in the diagnosis of pediatric OSA was examined. Overall, the evidence in children is limited. Feasibility studies that have been performed have on the whole shown good results, with several reporting > 90% of their home recordings as meeting predetermined quality criteria regarding signal artifact and minimum recording time. The limited data comparing type 2 studies with in-laboratory PSG have shown no significant differences in respiratory parameters. The results pertaining to diagnostic accuracy of type 3 home sleep apnea testing devices are conflicting. Although more research is needed, home testing with at least a type 3 portable monitor offers a viable alternative in the diagnosis of otherwise healthy children with moderate to severe OSA, particularly in settings where access to polysomnography is scarce or unavailable. Of note, since most studies have been performed in habitually snoring healthy children, home sleep apnea testing may not be applicable to children with other comorbid conditions. In particular, CO2 monitoring is important in children in whom there is concern regarding nocturnal hypoventilation, such as children with neuromuscular disease, underlying lung disease, or obesity hypoventilation, and most home testing devices do not include a transcutaneous or end-tidal CO2 channel.

Sleep Disordered Breathing in Children

Sleep-disordered breathing (SDB) refers to a group of disorders characterized by abnormalities of respiration or ventilation during sleep. It encompasses obstructive sleep apnea (OSA), central sleep apnea (CSA) syndromes, sleep-related hypoventilation and sleep-related hypoxemia disorders. This review will concentrate on the disorder most prevalent in pediatrics, i.e., OSA, highlighting the most recent developments in our understanding of the etiology, pathophysiology and treatment options of this condition. OSA morbidities primarily involve the neurocognitive, cardiovascular and metabolic systems. However, there can be significant phenotypic variation in terms of end organ morbidity for the same OSA severity. This is likely due to the interplay between genetic and environmental factors; recent developments in the fields of genomics and proteomics have the potential to shed light on these complex pathological cascades. As we enter the era of personalized medicine, phenotyping patients to enable clinicians to tailor bespoke clinical management plans will be of crucial importance.

Biomarkers associated with obstructive sleep apnea and morbidities: a scoping review

OBJECTIVE

To map potential biomarkers of obstructive sleep apnea (OSA)-associated morbidities in both adults and children, to identify gaps in current evidence, and to determine the value of conducting a full systematic review.

METHODS

A scoping review was undertaken of studies in patients with OSA that evaluated the potential value of biological markers in identifying OSA-associated morbidities. Retained articles were only those studies whose main objective was to identify morbidity biomarkers in subjects with OSA, the latter being confirmed with a full overnight polysomnography (PSG) in a laboratory or at-home settings. The methodology of the selected studies was classified using an adaptation of the evidence quality criteria recommended by the American Academy of Pediatrics. Additionally the biomarkers were categorized according to their potential clinical applicability.

RESULTS

572 citations were identified of which 48 met inclusion criteria. Thirty-four studies were conducted in adults and 14 involved children. Most of the studies evaluated blood biomarkers, and presented 31 potential diagnostic biomarkers.

CONCLUSION

The majority of studies that performed explored blood-based biomarkers, with most not identifying definitive morbidity biomarkers. Of the potentially promising morbidity biomarkers, plasma IL-6 and high sensitivity C-reactive protein appear to exhibit a favorable profile, and may discriminate OSA patients with and without morbidities in both adults and children. MRP 8/14 was retained in children as well as cardiovascular morbidity-associated biomarker. Urinary neurotransmitters may also provide a good tool for screening OSA cognitive morbidity in children.

Diagnostic capability of biological markers in assessment of obstructive sleep apnea: a systematic review and meta-analysis

OBJECTIVE

The purpose of this systematic review is to evaluate the diagnostic value of biological markers (exhaled breath condensate, blood, salivary and urinary) in the diagnosis of OSA in comparison to the gold standard of nocturnal PSG.

METHODS

Studies that differentiated OSA from controls based on PSG results, without age restriction, were eligible for inclusion. The sample of selected studies could include studies in obese patients and with known cardiac disease. A detailed individual search strategy for each of the following bibliographic databases was developed: Cochrane, EMBASE, MEDLINE, PubMed, and LILACS. The references cited in these articles were also crosschecked and a partial grey literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies.

RESULTS

After a two-step selection process, nine articles were identified and subjected to qualitative and quantitative analyses. Among them, only one study conducted in children and one in adults found biomarkers that exhibit sufficiently satisfactory diagnostic accuracy that enables application as a diagnostic method for OSA.

CONCLUSION

Kallikrein-1, uromodulin, urocotin-3, and orosomucoid-1 when combined have enough accuracy to be an OSA diagnostic test in children. IL-6 and IL-10 plasma levels have potential to be good biomarkers in identifying or excluding the presence of OSA in adults.

Biomarkers associated with obstructive sleep apnea: A scoping review

The overall validity of biomarkers in the diagnosis of obstructive sleep apnea (OSA) remains unclear. We conducted a scoping review to provide assessments of biomarkers characteristics in the context of obstructive sleep apnea (OSA) and to identify gaps in the literature. A scoping review of studies in humans without age restriction that evaluated the potential diagnostic value of biological markers (blood, exhaled breath condensate, salivary, and urinary) in the OSA diagnosis was undertaken. Retained articles were those focused on the identification of biomarkers in subjects with OSA, the latter being confirmed with a full overnight or home-based polysomnography (PSG). Search strategies for six different databases were developed. The methodology of selected studies was classified using an adaptation of the evidence quality criteria from the American Academy of Pediatrics. Additionally the biomarkers were classified according to their potential clinical application. We identified 572 relevant studies, of which 117 met the inclusion criteria. Eighty-two studies were conducted in adults, 34 studies involved children, and one study had a sample composed of both adults and children. Most of the studies evaluated blood biomarkers. Potential diagnostic biomarkers were found in nine pediatric studies and in 58 adults studies. Only nine studies reported sensitivity and specificity, which varied substantially from 43% to 100%, and from 45% to 100%, respectively. Studies in adults have focused on the investigation of IL-6, TNF-α and hsCRP. There was no specific biomarker that was tested by a majority of authors in pediatric studies, and combinatorial urine biomarker approaches have shown preliminary promising results. In adults IL-6 and IL-10 seem to have a favorable potential to become a good biomarker to identify OSA.

Pediatric obstructive sleep apnea

Obstructive sleep apnea syndrome (OSAS) is a disorder of airway obstruction with multisystem implications and associated complications. OSAS affects children from infancy to adulthood and is responsible for behavioral, cognitive, and growth impairment as well as cardiovascular and perioperative respiratory morbidity and mortality. OSAS is associated commonly with comorbid conditions, including obesity and asthma. Adenotonsillectomy is the most commonly used treatment option for OSAS in childhood, but efforts are underway to identify medical treatment options.

Poincaré plot width, morning urine norepinephrine levels, and autonomic imbalance in children with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) in childhood is accompanied by sympathetic overflow unopposed by the parasympathetic tone. Complex methods like power spectral analysis of heart rate variability have been applied to study this imbalance. In this report, width of Poincaré scattergram of the R-R interval (parasympathetic tone) and morning urine norepinephrine concentration (sympathetic activity) were used to assess autonomic imbalance.

METHODS

Poincaré plot was obtained from the electrocardiographic channel of nocturnal polysomnography and its width was measured, and norepinephrine-to-creatinine concentration ratio was calculated in morning urine specimen.

RESULTS

Twenty children with obstructive sleep apnea and moderate-to-severe nocturnal hypoxemia (oxygen saturation of hemoglobin [SpO(2)] nadir <90%), 24 subjects with mild hypoxemia (SpO(2) nadir ≥90%), and 11 control subjects were recruited. Children with obstructive sleep apnea and moderate-to-severe hypoxemia had significantly narrower Poincaré plot width (318.7 ± 139.3 ms) and higher ln-transformed urine norepinephrine-to-creatinine ratio (4.5 ± 0.6) than control subjects (484.2 ± 104.4 ms and 3.8 ± 0.4, respectively; P < 0.05). Ln-transformed urine norepinephrine levels were inversely related to Poincaré plot width (P = 0.02).

CONCLUSIONS

Subjects with obstructive sleep apnea and moderate-to-severe nocturnal hypoxemia have enhanced sympathetic activity and reduced parasympathetic drive. Poincaré plot width and urine norepinephrine levels are simple measures of autonomic imbalance in pediatric obstructive sleep apnea.

Evaluation and validation of a method for determining platelet catecholamine in patients with obstructive sleep apnea and arterial hypertension

Background

Measurements of plasma and urinary catecholamine are susceptible to confounding factors that influence the results, complicating the interpretation of sympathetic nervous system (SNS) activity in the Obstructive sleep apnea (OSA) and arterial hypertension (HYP) conditions.

Objective

In this study, we validated a test for platelet catecholamine and compared the catecholamine levels (adrenaline and noradrenaline) in urine, plasma and platelets in patients with OSA and HYP compared with controls.

Methods

In the validation, 30 healthy, nonsmoking volunteers who were not currently undergoing treatment or medication were selected as the control group. One hundred fifty-four individuals (114 OSA, 40 non-OSA) were consecutively selected from the outpatient clinic of the Sleep Institute and underwent clinical, polysomnographic and laboratory evaluation, including the urinary, plasma and platelet levels of adrenaline (AD) and noradrenaline (NA). Patients were then allocated to groups according to the presence of OSA and/or hypertension.

Results

A logistic regression model, controlled for age and BMI, showed that urinary AD and urinary NA were risk factors in the OSA+HYP group and the HYP group; however, the model showed higher levels of platelet NA for OSA without HYP. After 1 year of CPAP (continuous upper airway pressure) treatment, patients (n = 9) presented lower levels of urinary NA (p = 0.04) and platelet NA (p = 0.05).

Conclusion

Urinary NA and AD levels were significantly associated with the condition of hypertension with and without OSA, whereas platelet NA with OSA without comorbidity. These findings suggest that platelet catecholamine levels might reflect nocturnal sympathetic activation in OSA patients without hypertension.

The promise of translational and personalised approaches for paediatric obstructive sleep apnoea: an 'Omics' perspective

Obstructive sleep apnoea (OSA) can result in significant morbidities including the cardiovascular, metabolic and neurocognitive systems. These effects are purportedly mediated via activation of inflammatory cascades and the induction of oxidative stress, ultimately resulting in cellular injury and dysfunction. While great advances have been made in sleep medicine research in the past decades, there are still wide gaps in our knowledge concerning the exact underlying pathophysiological mechanisms of OSA and consequences. Without resolving these issues, the reasons why patients with a similar severity of OSA can have markedly different clinical presentation and end-organ morbidity, that is, phenotype, will continue to remain elusive. This review aims to highlight the recent exciting discoveries in genotype-phenotype interactions, epigenetics, genomics and proteomics related to OSA. Just as PCR revolutionised the field of genetics, the potential power of 'Omics' promises to transform the field of sleep medicine, and provide critical insights into the downstream pathological cascades inherent to OSA, thereby enabling personalised diagnosis and management for this highly prevalent sleep disorder.

Obstructive sleep apnea in children: a critical update

Obstructive sleep apnea (OSA) in children is a highly prevalent disorder caused by a conglomeration of complex pathophysiological processes, leading to recurrent upper airway dysfunction during sleep. The clinical relevance of OSA resides in its association with significant morbidities that affect the cardiovascular, neurocognitive, and metabolic systems. The American Academy of Pediatrics recently reiterated its recommendations that children with symptoms and signs suggestive of OSA should be investigated with polysomnography (PSG), and treated accordingly. However, treatment decisions should not only be guided by PSG results, but should also integrate the magnitude of symptoms and the presence or absence of risk factors and signs of OSA morbidity. The first-line therapy in children with adenotonsillar hypertrophy is adenotonsillectomy, although there is increasing evidence that medical therapy, in the form of intranasal steroids or montelukast, may be considered in mild OSA. In this review, we delineate the major concepts regarding the pathophysiology of OSA, its morbidity, diagnosis, and treatment.