Effects of obstructive sleep apnea and obesity on exercise function in children

Modelling metabolic performance in paediatric obstructive sleep disordered breathing: A case-control study

Paediatric obstructive sleep disordered breathing (OSDB) has a considerable impact on cardiovascular physiology, but the consequences on children's basal metabolism and response to exercise are far from being known. The objective was to propose model estimations for paediatric OSDB metabolism at rest and during exercise. A retrospective case-control analysis of data from children submitted to otorhinolaryngology surgery was performed. The heart rate (HR) was measured, while oxygen consumption (VO2) and energy expenditure (EE) at rest and during exercise were obtained using predictive equations. The results for the patients with OSDB were compared with controls. A total of 1256 children were included. A total of 449 (35.7%) had OSDB. The patients with OSDB showed a significantly higher resting heart rate (94.55 ± 15.061 bpm in OSDB vs. 92.41 ± 15.332 bpm in no-OSDB, p = 0.041). The children with OSDB showed a higher VO2 at rest (13.49 ± 6.02 mL min-1kg-1 in OSDB vs. 11.55 ± 6.83 mL min-1kg-1 in no-OSDB, p = 0.004) and a higher EE at rest (67.5 ± 30.10 cal min-1kg-1 in OSDB vs. 57.8 + 34.15 cal min-1kg-1 in no-OSDB, p = 0.004). At maximal exercise, patients with OSDB showed a lower VO2max (33.25 ± 5.82 mL min-1kg-1 in OSDB vs. 34.28 ± 6.71 in no-OSDB, p = 0.008) and a lower EE (166.3 ± 29.11 cal min-1kg-1 in OSDB vs. 171.4 ± 33.53 cal min-1kg-1 in no-OSDB, p = 0.008). The VO2/EE increment with exercise (Δ VO2 and Δ EE) was lower in OSDB for all exercise intensities (p = 0.009). This model unveils the effect of paediatric OSDB on resting and exercise metabolism. Our findings support the higher basal metabolic rates, poorer fitness performance, and cardiovascular impairment found in children with OSDB.

Influence of physical fitness and weight status on autonomic cardiac modulation in children

BACKGROUND

This study provides reference values for cardiovascular modulation at rest, during maximal exercise test and recovery after exercise in Caucasian children according to weight status and cardiorespiratory fitness (CRF) level. Additionally, the current study analyzed several correlations between autonomic cardiovascular modulation, cardiorespiratory performance and cardiometabolic risk. The principal goal of this study was to analyze cardiac function at rest, during maximum exercise, and during the recovery phase in children grouped according to weight status and CRF level.

METHODS

One hundred and fifty-two healthy children (78 girls) 10-16 years of age were divided into three groups: soccer and basketball players (SBG), endurance group (EG), and sedentary people with overweight and obesity (OOG). A cardiac RR interval monitor recorded the cardiac data and specific software analyzed the cardiac autonomic response through heart rate (HR) and HR variability. The study analyzed resting HR (RHR), HRpeak, and HR recovery (HRR).

RESULTS

OOG showed significant poorer performance in the Léger test lower V̇O2 max and higher values of blood pressure at rest and post-exercise than sport groups. The EG presented the best results in CRF and cardiometabolic risk (CMR) in relation to SBG and OOG. The OOG showed higher percentage of HR values, compatible with an unhealthy cardiovascular autonomic modulation than the sport groups, with significant differences in bradycardia, HR reserve, and HRR 5 min.

CONCLUSIONS

Aerobic performance, vagal activity, blood pressure, chronotropic competence, and HRR have significant associations with CMR parameters.

IMPACT

The current study presents reference values of autonomic cardiac function in Caucasian children according to weight status and cardiorespiratory fitness level. Aerobic performance, vagal activity, blood pressure, chronotropic competence, and heart rate during the recovery period after exercise have significant associations with cardiometabolic risk parameters. Children with overweight and obesity show signs of autonomic dysfunction reflected as low cardiac vagal activity and poor chronotropic competence.

Comprehensive cardiac evaluation to maximal exercise in a contemporary population of prepubertal children

BACKGROUND

Heart rate (HR) is a biomarker used to measure physiological function, health status and cardiovascular autonomic function. The purpose of this study was to determine sex- and age-specific reference values for cardiac autonomic function at rest, during maximal exercise and the recovery phase in prepubertal children.

METHODS

Five hundred and twelve healthy children 7-11 years of age performed a Léger test. A heart RR-interval monitor recorded the heart data and a specific software analysed the cardiac autonomic response through HR and HR variability (HRV). It analysed HR before the test (resting HR, RHR), during the test (HR_peak) and HR recovery (HRR) in the first minute (HRR1) and the fifth minute (HRR5). The values are mean ± SD.

RESULTS

Collectively, 91.2% of girls and 92.3% of boys were within the recommended ranges regarding RHR. The average HR_peak was 199 ± 10.83 b.p.m. and 96.8% of girls and 95.3% of boys were within the minimum threshold value recommended (180 b.p.m.). Boys showed lower values of RHR than girls (p < 0.001) and larger values of HRR 1 and HRR5 (p < 0.001).

CONCLUSIONS

This study comprehensively provides a reference set of data for the most important HR variables that can be obtained during exercise testing in prepubertal children regarding age and sex and in a field setting.

IMPACT

This is the first study to provide reference values of autonomic cardiac function at rest, during maximal exercise and during the recovery period in prepubertal children aged 7-11 years. Despite the early age of participants, cardiorespiratory fitness, RHR and HRR are different according to sex. Aerobic performance and HR_peak have a negative correlation with body mass index and cardiometabolic risk.

OSA and cardiorespiratory fitness: a review

The effects of untreated obstructive sleep apnea (OSA) on cardiopulmonary function remain unclear. Cardiorespiratory fitness (CRF), commonly reflected by VO₂ max measured during cardiopulmonary exercise testing, has gained popularity in evaluating numerous cardiopulmonary conditions and may provide a novel means of identifying OSA patients with the most clinically significant disease. This emerging testing modality provides simultaneous assessment of respiratory and cardiovascular function with results helping uncover evidence of evolving pathology in either organ system. In this review, we highlight the current state of the literature in regard to OSA and CRF with a specific focus on changes in cardiovascular function that have been previously noted. While OSA does not appear to limit respiratory function during exercise, studies seem to suggest an abnormal cardiovascular exercise response in this population including decreased cardiac output, a blunted heart rate response (ie, chronotropic incompetence), and exaggerated blood pressure response. Surprisingly, despite these observed changes in the cardiovascular response to exercise, results involving VO₂ max in OSA remain inconclusive. This is reflected by VO₂ max studies involving middle-aged OSA patients showing both normal and reduced CRF. As prior studies have not extensively characterized oxygen desaturation burden, we propose that reductions in VO₂ max may exist in OSA patients with only the most significant disease (as reflected by nocturnal hypoxia). Further characterizing this relationship remains important as some research suggests that positive airway pressure therapy or aerobic exercise may improve CRF in patients with OSA. In conclusion, while it likely that severe OSA, via an abnormal cardiovascular response to exercise, is associated with decreased CRF, further study is clearly warranted to include determining if OSA with decreased CRF is associated with increased morbidity or mortality.

CITATION

Powell TA, Mysliwiec V, Brock MS, Morris MJ. OSA and cardiorespiratory fitness: a review. J Clin Sleep Med. 2022;18(1):279-288.

Hypertension in Children with Obstructive Sleep Apnea Syndrome-Age, Weight Status, and Disease Severity

Older age, obesity, and obstructive sleep apnea syndrome (OSAS) are known to increase the risk of hypertension in adults. However, data for children are scarce. This study aimed to investigate the relationships between hypertension, age, weight status, and disease severity in 396 children with OSAS. The prevalence rates of hypertension, obesity, and severe OSAS (apnea-hypopnea index ≥10) were 27.0%, 28.0%, and 42.9%, respectively. Weight z-score and apnea-hypopnea index were independently correlated with systolic blood pressure z-score, and minimal blood oxygen saturation (SpO₂) was independently associated with diastolic blood pressure z-score. Overall, late childhood/adolescence (odds ratio (OR) = 1.72, 95% CI = 1.05–2.81), obesity (OR, 2.58, 95% CI = 1.58–4.22), and severe OSAS (OR = 2.38, 95% CI = 1.48–3.81) were independent predictors of pediatric hypertension. Furthermore, late childhood/adolescence (OR = 2.50, 95% CI = 1.10–5.71) and abnormal SpO₂ (mean SpO₂ < 95%; OR = 4.91, 95% CI = 1.81–13.27) independently predicted hypertension in obese children, and severe OSAS (OR = 2.28, 95% CI = 1.27–4.10) independently predicted hypertension in non-obese children. In conclusion, obesity, OSAS severity, and abnormal SpO₂ are potentially modifiable targets to improve hypertension while treating children with OSAS.

Attenuated heart rate recovery in children and adolescents with obstructive sleep apnea syndrome

BACKGROUND

Autonomic dysfunction is a key trait in the development of obstructive sleep apnea syndrome (OSAS) in adults. However, few similar studies focused on children and adolescents. We investigated if there was any association between heart rate recovery (HRR) and the severity of OSAS in children and adolescents.

METHODS

A total of 161 subjects were included: 87 healthy controls, 35 mild OSAS patients (M-OSAS) and 39 moderate-severe OSAS (M-S-OSAS) patients. Clinical parameters, cardiopulmonary exercise test (CPET) indexes including HRR and polysomnographic records including apnea-hypopnea index (AHI) were compared among the three groups. Pearson correlation analysis and multivariable linear regression analysis were used to detect the relationship between HRR and polysomnographic parameters.

RESULTS

HRR values in either the OSAS group were lower than those of the control group, and the values in the M-S OSAS group were even lower than those of the M-OSAS group (P < 0.05). Correlation analysis showed that HRR was inversely correlated with AHI (r = -0.190, P < 0.01). Moreover, multivariable linear regression analyses showed the association between HRR and AHI was significant (β = 0.174, P < 0.01).

CONCLUSIONS

HRR was closely associated with OSAS severity, which suggested that HRR might be a promising index for risk stratification and clinical management in children and adolescents with OSAS.

IMPACT

Heart rate recovery (HRR), a noninvasive and reliable index of automatic nervous system, is closely associated with the severity of obstructive sleep apnea syndrome (OSAS) in children and adolescents. To our knowledge, our study was the first study in China focusing on evaluating the role of HRR in children with OSAS. We found HRR was closely associated with OSAS severity in children and adolescents, and it suggested that HRR might be a promising index for risk stratification and clinical management in children and adolescents with OSAS.

Neural crest-specific deletion of Bmp7 leads to midfacial hypoplasia, nasal airway obstruction, and disordered breathing modelling Obstructive Sleep Apnea

Pediatric obstructive sleep apnea (OSA), a relatively common sleep-related breathing disorder (SRBD) affecting approximately 1-5% of children, is often caused by anatomical obstruction and/or collapse of the nasal and/or pharyngeal airways. The resulting sleep disruption and intermittent hypoxia lead to various systemic morbidities. Predicting the development of OSA from craniofacial features alone is currently not possible and a controversy remains if upper airway obstruction facilitates reduced midfacial growth or vice-versa. Currently, there is no rodent model that recapitulates both the development of craniofacial abnormalities and upper airway obstruction to address these questions. Here, we describe that mice with a neural crest-specific deletion of Bmp7 (Bmp7ncko) present with shorter, more acute angled cranial base, midfacial hypoplasia, nasal septum deviation, turbinate swelling and branching defects, and nasal airway obstruction. Interestingly, several of these craniofacial features develop after birth during periods of rapid midfacial growth and precede the development of an upper airway obstruction. We identified that in this rodent model, no single feature appeared to predict upper airway obstruction, but the sum of those features resulted in a reduced breathing frequency, apneas and overall reduced oxygen consumption. Metabolomics analysis of serum from peripheral blood identified increased levels of hydroxyproline, a metabolite upregulated under hypoxic conditions. As this model recapitulates many features observed in OSA, it offers unique opportunities for studying how upper airway obstruction affects breathing physiology and leads to systemic morbidities.

Consequences of paediatric sleep disordered breathing: contributions from Australian and New Zealand investigators

AIMS

To highlight the contributions of Australian and New Zealand researchers to the identification of the consequences of paediatric sleep disordered breathing (SDB).

METHODS

A search was conducted in PubMed using the terms "sleep disordered breathing" "child" and "Australia or New Zealand". All abstracts were reviewed and those which focused on the consequences of SDB have been included.

RESULTS

Australasian research into the consequences of SDB has grown exponentially over the last 35 years. SDB has significant adverse consequences for quality of life, behaviour, neurocognition and the cardiovascular system and the Australasian research studies investigating these are summarised.

CONCLUSIONS

Australian and New Zealand researchers have played a significant role in understanding the consequences of paediatric SDB and the mechanisms which underpin these. The research conducted "Downunder" has led the world in this field of research and will continue to provide evidence to improve the lives of children not only in Australasia but around the world.

TcCO2 changes correlate with partial obstruction in children suspected of sleep disordered breathing

INTRODUCTION

Pediatric sleep disordered breathing (SDB) is characterized by long periods of partial upper airway obstruction (UAO) with low apnea-hypopnea indices (AHI). By measuring snoring and stertor, Sonomat studies allow quantification of these periods of partial UAO.

AIM

To determine whether transcutaneous CO₂ (TcCO₂ ) levels correlate with increasing levels of partial UAO and to examine patterns of ΔTcCo₂ in the transitions from (a) wakefulness to sleep and (b) non-rapid eye movement (NREM) to rapid eye movement (REM) sleep.

METHODS

This was a retrospective review of sleep studies in seven asymptomatic controls aged 7 to 12 years and 62 symptomatic children with suspected SDB and no comorbidities, aged 2 to 13 years. Both groups underwent overnight polysomnography, including continuous TcCO₂ , at one of two pediatric hospitals in Sydney. Changes in carbon dioxide levels between wake to NREM (sleep onset) and NREM to REM sleep were evaluated using an all-night TcCO₂ trace time-linked to a hypnogram. Paired Sonomat recordings were used to quantify periods of UAO in the symptomatic group.

RESULTS

The ΔTcCO₂ at sleep onset was greater in SDB children than controls and ΔTcCO₂ with sleep onset correlated with the duration of partial obstruction (r = .60; P < .0001). Children with an increase in TcCO₂ from NREM to REM had a higher number of snoring and stertor events compared to those in whom TcCO₂ decreased from NREM to REM (91 vs 30 events/h; P = < .0001).

CONCLUSIONS

In children without comorbidities, the measurement of TcCO₂ during sleep correlates with indicators of partial obstruction.

Diagnosis and management of childhood sleep-disordered breathing. Clinical approach

Sleep-disordered breathing (SDB) includes disorders of breathing that affect airway patency, which impair children's sleep and lead to negative consequences. Obstructive sleep apnea, hypoventilation and upper airway resistance syndrome are common causes of morbidity and mortality in childhood. These clinical practice guidelines, intended for use by pediatricians and primary care clinicians, provide a clear recommendation for the diagnosis and management of sleep-disordered breathing, focusing on the most serious disorder, obstructive sleep apnea syndrome (OSAS). These clinical guidelines formulate clear recommendations to identify patients with suspected OSAS. Further, the manuscript will highlight the potential consequences of SBD in children, and how to overcome such difficulties, what could be the therapeutic options, a 12 recommendations and what are the future direction for pediatric sleep medicine.

Nocturnal enuresis in obese children: a nation-wide epidemiological study from China

Childhood obesity increases the risk of obstructive sleep apnea syndrome, type 2 diabetes mellitus, cardiovascular abnormalities, and psychological and behavioral disorders. But it is unclear whether obesity is associated with childhood nocturnal enuresis (NE). This study aimed to assess the relationship between childhood obesity and NE in a nationally representative large sample in China. Subjects were enrolled from Urumqi, Chengdu, Xi'an, Hohhot, Wuhan, Canton, Shanghai, and Harbin cities in China in November and December 2005. The survey included 20,987 children aged 5-12 years and they and their caregivers completed questionnaires. Height and weight were measured by school teachers trained in healthcare. According to the WHO child growth standards, obesity was defined as a body mass index >95th percentile of peers with the same age and gender. NE was defined as bed wetting for more than twice a week for 3 consecutive months. Demographic variables were compared among different groups. The prevalence of obesity, asthma, attention-deficit/hyperactivity disorder (ADHD), depressive moods, and snoring were different between the NE and without-NE groups (P < 0.05). The raw odds ratio (OR) for NE and obesity was 1.36 (95%CI = 1.07-1.74; P = 0.013) and the adjusted OR was 1.42 (95%CI = 1.11-1.82; P = 0.005) in the multivariable analysis. When adjusting for co-occurring conditions, the results showed that asthma did not affect the risk of NE (OR = 1.42, 95%CI = 1.11-1.82; P = 0.005), but ADHD (OR = 1.41; 95%CI = 1.10-1.81; P = 0.006) and depressive moods (OR = 1.34; 95%CI = 1.07-1.76; P = 0.012) slightly weakens the association between NE in children and obesity, while snoring weakens the association between obesity and NE and the risk became non-significant (OR = 1.21; 95%CI = 0.94-1.56; P = 0.138). In conclusion, obese children were at a higher risk of incurring NE compared to non-obese children. This association was weaker in children who either snored, had ADHD, or had depressive mood.

Obesity Affects Submaximal Oxygen Uptake-Heart Rate Relationship and Exercise Economy Differently in Pre- and Post-pubescent Boys and Girls

The purpose of this study was to develop regression equations for estimating the intensity of the exercise work rate (relative peak oxygen uptake-heart rate [%VO₂-HR]) and the metabolic energy expenditure (MEE) for exercise prescription and rehabilitation medicine that are specific to children. This study took into account that the specific data in terms of obesity, sex, and pubertal status are currently unavailable. Our hypothesis was that obesity would affect the submaximal exercise the oxygen uptake (VO₂), heart rate (HR), and metabolic energy expenditure (MEE), and exercise economy (ExEco). In this retrospective study, the regression analysis was performed on 126 children, matching groups for Tanner pubertal status (prepubertal: 1.8±0.7; postpubertal: 4.1±0.7), BMI-for-age percentile (lean: 50±26; obese: 96±4), and sex (girls: 48%; boys: 52%). Percent peakVO₂ was regressed against HR, MEE against work rate (watt), and exercise economy (ExEco, mLO₂·kg lean body mass^-1·min^-1) against work rate. Additionally, stepwise linear regression was used to identify predictors for exercise peak work rate. Prepubertal and postpubertal boys exercise at lower work rates than obese (%peakVO2-HR slope; P=0.01). The reverse was true in girls, lean prepubertal work at lower compared lean postpubertal (%peakVO2-HR slope; P=0.03). Boys expend more calories during exercise compared to girls (MEE-slope; P=0.01), with no effect of puberty or obesity. Obese prepubertal children have poor ExEco compared to lean prepubertal children (ExEco-work rate slopes; P<0.01) but not in postpubertal children. Strong correlations (r=0.92-0.94) for %peakVO₂-HR and MEE regressions for boys and girls accounted for 85-92% variation. Height, lean leg, and leg fat mass accounted for 83% of the variance for predicting peak work rate. Obesity, sex, and puberty affect exercise characteristics in children and should be considered for an individualized approach to exercise prescription in children.

The shifting relationship between weight and pediatric obstructive sleep apnea: A historical review

OBJECTIVES

For more than a century, pediatric obstructive sleep apnea (OSA) was associated with failure to thrive. However, that association has faded over the last few decades. A 21st century child with OSA is much more likely to be overweight than underweight. This raises the question: Has pediatric OSA changed over time, or has the rise of childhood obesity in the United States created a new, separate disease? This literature review explores the historical shift in the relationship between weight and OSA, and the associated changes in treatment.

RESULTS

We demonstrate a clear transition in the prevalence of failure to thrive and obesity in the OSA literature in the mid-2000s. What is less clear is whether these two clinical phenotypes should be considered two distinct diseases, or whether subtle differences in one set of pathophysiologic pathways-adenotonsillar hypertrophy, altered inflammation, and increased energy expenditure-can lead to divergent metabolic outcomes. More research is needed to fully elucidate the pathophysiology of OSA in children with obesity.

CONCLUSIONS

We may need new and different treatments for obesity-associated OSA as adenotonsillectomy-which is effective at reversing failure to thrive in OSA-is not as effective at treating OSA in children with obesity. One option is drug-induced sleep endoscopy, which could personalize and improve surgical treatment of OSA. There is some evidence that therapies used for OSA in adults (e.g., weight loss and positive airway pressure) are also helpful for overweight/obese children with OSA. Laryngoscope, 129:2414-2419, 2019.

[Exercise capacity in children with mild sleep-disordered breathing]

INTRODUCTION

While the association between sleep-disordered breathing (SDB) and low physical activity has been reported in children, little information is available on the impact of SDB on exercise capacity. The aim of this study was to assess exercise capacity in children with SDB in order to estimate the relevance of exercise training intervention.

METHODS

Twelve young patients with suspected SDB matched with 11 presumably healthy subjects of same age range (aged 13±0.5yr) were investigated. Both groups underwent physical activity assessment, full night polysomnography, incremental and all-out exercise tests.

RESULTS

The respiratory disturbance index was higher in the patient group (4.6±4.7 vs 0.8±0.6; P=0.02). Children with SDB had lower VO₂max (32.0±9.9 vs 42.3±5.7mL.kg^-1.min^-1, P=0.007) and lower peak power (8.6±3.4 vs 11.8±1.9W.kg^-1, P=0.009). A significant correlation between VO₂max and weekly physical activity only was found in the SDB group (P=0.005).

CONCLUSION

Mild SDB may be associated with impairment of both aerobic and anaerobic exercise capacity in children, related to poor physical activity. Exercise training could bring clinical benefit in this population.

The effects of obesity on pulmonary function in children

The prevalence of obesity has risen rapidly in the United States in the past 20 years. Up to 25% of US children are obese, and obesity can be directly correlated with immediate and long-term health consequences. Pediatric obesity can harm multiple body systems and is a public health issue. This article focuses on how obesity affects a child's respiratory system, including pulmonary function, exercise intolerance, gas exchange, and airway musculature.

The weighty issue of obesity in paediatric respiratory medicine

Some have observed that developed world is fat and getting fatter. This is even extending into the developing world, and it is important to appreciate that the consequences of childhood obesity last into adulthood and are associated with premature death. From the paediatric respiratory perspective, the deposition of excess adipose tissue in the thoraco-abdominal region begins early in life and is believed to alter diaphragm mobility and chest wall expansion, reduce lung compliance, and result in a rapid shallow breathing pattern with an increased work of breathing and reduction in maximum ventilatory capacity. This results in respiratory symptoms of exertional dyspnoea related to deconditioning which may present as exercise limitation, leading to confusion with common lung diseases such as asthma. The manifestations of the increasingly prevalent problems of overweight and obesity in young people and their interaction with common conditions of asthma and obstructive sleep apnoea will be discussed.

Prevalence of Sleep Disorders in Thai Children

OBJECTIVE

To evaluate the prevalence of sleep disorders in Thai children who underwent polysomnography at a single institution.

METHODS

A retrospective analysis of pediatric polysomnographic studies was performed from January 2011 through December 2014.

RESULTS

One hundred sixty-six studies were conducted; 142, 7, and 17 were diagnostic, split-night, and positive airway pressure (PAP) titration studies, respectively. In total, 136 diagnostic/split-night studies were performed to diagnose sleep disorders with presentation of snoring (92.6 %), heavy breathing (0.7 %), witnessed apnea (14.7 %), excessive daytime sleepiness (10.3 %), hyperactivity (2.2 %), restless sleep (11.0 %), enuresis/nocturia (5.9 %), abnormal behavior (4.4 %) and poor weight gain (0.7 %). Eleven diagnostic studies and one split-night study were performed to follow-up obstructive sleep apnea (OSA) after adenoidectomy and/or tonsillectomy. One diagnostic study was conducted to follow-up OSA after postmandibular distraction. OSA was the most common diagnosis with a prevalence of 92.7 %; 40.4 % of patients were diagnosed with severe OSA. The prevalence of sleep-related hypoventilation was 15.4 %. The second most common diagnosis was periodic limb movement disorder with a prevalence of 20.6 %. Seventeen PAP titration studies were performed. Four CPAP titration studies were conducted for OSA treatment. Twelve bi-level (BiPAP) titration studies were performed in eight children with hypoventilation. One BiPAP/average volume-assured pressure support titration was conducted in a patient with congenital central hypoventilation syndrome (CCHS).

CONCLUSIONS

The prevalence of sleep disorders in Thai children who underwent polysomnography at a tertiary-care hospital is very high. The factors that contribute are the limited availability and high costs of polysomnography in Thailand. This information will encourage pediatricians to look for sleep disorders in children.

Update on paediatric obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is one of the most common causes of sleep-disordered breathing (SDB) in children. It is associated with significant morbidity, potentially impacting on long-term neurocognitive and behavioural development, as well as cardiovascular outcomes and metabolic homeostasis. The low grade systemic inflammation and increased oxidative stress seen in this condition are believed to underpin the development of these OSA-related morbidities. The significant variance in degree of end organ morbidity in patients with the same severity of OSA highlights the importance of the interplay of genetic and environmental factors in determining the overall OSA phenotype. This review seeks to summarize the current understanding of the aetiology and mechanisms underlying OSA, its risk factors, diagnosis and treatment.

Viewpoint article: Childhood obesity--looking back over 50 years to begin to look forward

The last 50 years have seen the emergence of childhood obesity as a major public health concern and a condition now regularly encountered in routine general paediatric practice. Causes are extremely complex, bringing together multifactorial environmental factors and individual genetics, and we still do not have a clear understanding of why some children appear predisposed to exaggerated and sometimes extreme weight gain. Overweight and obese children of today face an uncertain future. They are likely to experience higher rates of type 2 diabetes and heart disease, as well as many other health problems. However, while the prevalence of childhood obesity has progressively increased over the last few decades, so has research into its underlying causes. This has led to large-scale trials aimed at improving prevention or treatment. As data have emerged from such studies, we have begun to accept that the heterogeneity of obesity means that broad 'common sense' strategies to address diet and activity will not lead to success on their own. Now is the time to begin to build on this information, dispelling myths and beliefs, in order to focus research efforts and take first steps towards more sophisticated strategies that go beyond the surface behaviours that simply potentiate obesity. Through carefully designed studies, aimed at tackling fundamental questions missed in the hasty development of 'common sense' approaches, will come answers that can lead to the development of more effective community- and health-care-orientated prevention and treatment programmes.

Obesity and its impact on the respiratory system

Obesity has complex and incompletely understood effects upon the respiratory system in childhood, which differs in some aspects to those seen in adults. There is increasing evidence that excess adiposity will impact negatively upon static and dynamic respiratory function as measured through lung volumes, lung compartment mechanics, measures of airway function and exercise capability to varying degrees. Further information is needed to better understand the effects in children, and the importance of onset and duration of obesity on subsequent outcomes. Consensus about how best to express adiposity is also an essential part of this process and fat distribution is another important factor. From a clinical standpoint this creates challenges in distinguishing a deconditioned obese young person from a non-atopic asthmatic because of symptom overlap and lung function testing results, including responses seen during airway challenges. There is evidence to support the role of weight loss in achieving normalisation of lung function parameters, but as always with obesity there are enormous challenges in realising this goal for many subjects.

Cross-regional analysis of multiple factors associated with childhood obesity in India: a national or local challenge?

OBJECTIVE

To investigate obesogenic co-causing factors, promoting rise of weight in children, associated to local differences in India.

METHODS

Overall 1,680 children, aged 3-11 and balanced by gender, were recruited in school contexts distributed in seven major Indian cities. All children were weighted and measured in order to calculate their BMI. A validated cultural specific questionnaire was administered to children's parents for assessing socio-demographic data, eating habits, physical activity, etc. Furthermore children's brand awareness scores were computed in order to analyze their affiliation towards food-based advertisement. Descriptive statistics of frequencies, duration and intensity of the various factors were performed. Chi-square tests or Wilcoxon signed rank test were used for evaluating significance of differences in factors distribution across Indian cities.

RESULTS

Four factors, promoting rise of children's weight, were individuated as associated to urban differences, namely meal times consumed in the family, parents' BMI, brand awareness and physical activity. These aspects exercised a significant impact on children's body size in Kolkata and Chennai. Hyderabad and Mumbai, instead, were the cities where religion played some role in influencing children's weight gain.

CONCLUSIONS

Such findings underline the need to frame obesity as a situated phenomenon rather than a national problem. Health policies, implemented in treating and preventing obesity, should be therefore specifically focused on locally situated peculiarities.