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

Frequent hypoxemia found in infants with bronchopulmonary dysplasia after weaning home oxygen

OBJECTIVE

Parental reports and brief clinical examinations are the primary information used to assist clinicians in weaning home supplemental oxygen in infants with bronchopulmonary dysplasia (BPD). Recorded nocturnal oximetry provides an objective assessment of hypoxemia; however, it is unknown if it identifies clinically undetected hypoxemia in the home setting. Our objective was to determine if nocturnal oximetry can identify unreported hypoxemia in infants with BPD who appear ready to wean from supplemental oxygen.

STUDY DESIGN

We conducted a retrospective chart review of infants born <32 weeks gestation with BPD who were discharged to home receiving supplemental oxygen and completed recorded nocturnal oximetry in room air during an 18-month period. Abnormal oximetry was defined as >5 min with SpO₂  < 90% and/or an oxyhemoglobin desaturation index (ODI4) >5. Comparative analysis of patients with normal and abnormal overnight oximetry was performed using Fisher Exact and Wilcoxon signed-rank test.

RESULTS

Thirty-five former premature infants completed nocturnal oximetry at 5.8 (3.4-8.3) months corrected age. Nocturnal oximetry was abnormal as defined in 67% of the cohort (n = 21). Five percent of patients were hypoxemic, 52% had frequent desaturation events, and 43% had both. No significant differences existed in neonatal characteristics between patients with normal and abnormal studies.

CONCLUSIONS

Nocturnal oximetry was abnormal in the majority of infants with BPD who were otherwise clinically ready to wean from oxygen support, suggesting that recorded home oximetry could be a feasible and useful tool to evaluate for otherwise clinically unapparent nocturnal hypoxemia in patients with BPD.

Blood pressure variability in children with obesity and sleep-disordered breathing following positive airway pressure treatment

Obese youth with sleep-disordered breathing are treated with positive airway pressure to improve sleep and cardiovascular status. While improvements in sleep parameters have been confirmed, a study by Katz et al. showed no major improvement in ambulatory blood pressure. The aim of this ancillary study was to analyze short-term blood pressure variability, following positive airway pressure treatment, as a more sensitive marker of cardiovascular health. We analyzed 24-h blood pressure variability data in 17 children, taken at baseline and after 12 months of treatment. These data were derived from an already published prospective, multicenter cohort study conducted in 27 youth (8-16 years) with obesity who were prescribed 1-year of positive airway pressure for moderate-severe sleep-disordered breathing. Significant decreases were found in 24 h systolic blood pressure (p = 0.040) and nighttime diastolic blood pressure (p = 0.041) average real variability, and diastolic blood pressure (p = 0.035) weighted standard deviation. Significant decreases were noted in nighttime diastolic blood pressure time rate variability (p = 0.007). Positive airway pressure treatment resulted in a significant decrease in blood pressure variability, suggesting a clinically significant improvement of sympathetic nerve activity in youth with obesity and sleep-disordered breathing. IMPACT: Cardiovascular variability, as measured by blood pressure variability, is improved in children following positive airway pressure treatment. Our novel findings of improved blood pressure time rate variability are the first described in the pediatric literature. Future studies aimed at analyzing target organ damage in this patient population will allow for a better understanding as to whether alterations in blood pressure variability translate to decreasing target organ damage in children, as seen in adults.

The impact of obstructive sleep apnea on endothelial function during weight loss in an obese pediatric population

BACKGROUND

Childhood obesity is an increasing problem with substantial comorbidities such as obstructive sleep apnea (OSA) and increased cardiovascular morbidity. Endothelial dysfunction is an underlying mechanism related to both obesity and OSA.

RESEARCH QUESTION

To investigate the effect of weight loss on endothelial function and OSA in obese children and to determine whether a change in endothelial function can be linked to an improvement in OSA.

METHODS

Obese children between 8 and 18 years of age were recruited while entering a 12-month inpatient weight loss program. Patients were followed at 3 study visits: baseline, after 10 months of weight loss, and 6 months after ending the program (18 months). Anthropometry and endothelial function (EndoPAT) were determined at all study visits. At baseline, sleep screening with a portable device (ApneaLink) was performed. This was repeated after 10 months if OSA was diagnosed at baseline.

RESULTS

At baseline, 130 children were included, of which 87 had OSA (67%). Seventy-two patients attended the follow-up visit at 10 months, and 28 patients attended the follow-up visit at 18 months. The BMI z-score decreased after 10 months (from 2.7 (1.4-3.4) to 1.7 (0.5-2.7); p < 0.001) and remained stable at 18 months. Endothelial function improved significantly after weight loss, evidenced by a shorter time to peak response (TPR) and higher reactive hyperemia index (p = 0.02 and p < 0.001), and remained improved after 18 months (p < 0.001 and p = 0.007). After 10 months of weight loss, 10 patients had residual OSA. These patients had a higher TPR at 10 months (225 (75-285)s) than those without OSA (135 (45-225)s) and patients with a normalized sleep study (105 (45-285)s; p = 0.02). Linear mixed models showed that more severe OSA was associated with a worse TPR at baseline and less improvement after weight loss.

CONCLUSION

Weight loss improves endothelial function in an obese pediatric population. However, even after weight loss, endothelial function improved less in the presence of OSA.

The Different Facets of Heart Rate Variability in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), a heterogeneous and multifactorial sleep related breathing disorder with high prevalence, is a recognized risk factor for cardiovascular morbidity and mortality. Autonomic dysfunction leads to adverse cardiovascular outcomes in diverse pathways. Heart rate is a complex physiological process involving neurovisceral networks and relative regulatory mechanisms such as thermoregulation, renin-angiotensin-aldosterone mechanisms, and metabolic mechanisms. Heart rate variability (HRV) is considered as a reliable and non-invasive measure of autonomic modulation response and adaptation to endogenous and exogenous stimuli. HRV measures may add a new dimension to help understand the interplay between cardiac and nervous system involvement in OSA. The aim of this review is to introduce the various applications of HRV in different aspects of OSA to examine the impaired neuro-cardiac modulation. More specifically, the topics covered include: HRV time windows, sleep staging, arousal, sleepiness, hypoxia, mental illness, and mortality and morbidity. All of these aspects show pathways in the clinical implementation of HRV to screen, diagnose, classify, and predict patients as a reasonable and more convenient alternative to current measures.

Heart rate variability spectrum characteristics in children with sleep apnea

BACKGROUND

Classic spectral analysis of heart rate variability (HRV) in pediatric sleep apnea-hypopnea syndrome (SAHS) traditionally evaluates the very low frequency (VLF: 0-0.04 Hz), low frequency (LF: 0.04-0.15 Hz), and high frequency (HF: 0.15-0.40 Hz) bands. However, specific SAHS-related frequency bands have not been explored.

METHODS

One thousand seven hundred and thirty-eight HRV overnight recordings from two pediatric databases (0-13 years) were evaluated. The first one (981 children) served as training set to define new HRV pediatric SAHS-related frequency bands. The associated relative power (RP) were computed in the test set, the Childhood Adenotonsillectomy Trial database (CHAT, 757 children). Their relationships with polysomnographic variables and diagnostic ability were assessed.

RESULTS

Two new specific spectral bands of pediatric SAHS within 0-0.15 Hz were related to duration of apneic events, number of awakenings, and wakefulness after sleep onset (WASO), while an adaptive individual-specific new band from HF was related to oxyhemoglobin desaturations, arousals, and WASO. Furthermore, these new spectral bands showed improved diagnostic ability than classic HRV.

CONCLUSIONS

Novel spectral bands provide improved characterization of pediatric SAHS. These findings may pioneer a better understanding of the effects of SAHS on cardiac function and potentially serve as detection biomarkers.

IMPACT

New specific heart rate variability (HRV) spectral bands are identified and characterized as potential biomarkers in pediatric sleep apnea. Spectral band BW1 (0.001-0.005 Hz) is related to macro sleep disruptions. Spectral band BW2 (0.028-0.074 Hz) is related to the duration of apneic events. An adaptive spectral band within the respiratory range, termed ABW3, is related to oxygen desaturations. The individual and collective diagnostic ability of these novel spectral bands outperforms classic HRV bands.

Perioperative complications of pediatric otorhinolaryngological operations

BACKGROUND

The identification of risk factors for the development of perioperative complications is one of the most important problems of pediatric anesthesiology.

PURPOSE

To identify risk factors for the development of perioperative complications in children undergoing ambulatory surgical interventions on ENT organs.

METHODS

Total of 141 patients were examined at the age from 7 to 17 years. Depending on the presence of complications all patients were divided into three groups: «No complications» (n = 64), «One complication» (n = 55) and «Two or more complications» (n = 22). The study was carried out in the following areas: Preoperative clinical status, intraoperative and postoperative complications. The severity of nasal breathing disorders was determined rhinomanometrically. 31 children underwent somnography. In the study of heart rate variability was evaluated. Intraoperative complications included: Cardiac arrhythmias, arterial hypertension and desaturation less than 90%. Postoperative complications included: Cardiorespiratory complications, pain, delirium, postoperative nausea and vomiting.

RESULTS

The most significant complication in the intraoperative period is desaturation below 90%, in the postoperative period they are pain, nausea and vomiting. Risk factors for the development of complications in the perioperative period are a decrease in the thyromental distance, hyperplasia of the tonsils of the third degree, Malampati score ≥ to 2 points, parents' bad habits, combined neurological and respiratory pathologies in a child, an assessment of the class «allergology» of the ASPOND scale is not less than 180 points and the prevalence of vagal influences.

CONCLUSIONS

The obtained results indicate that the presence of risk factors for perioperative complications during operations on ENT organs in children are associated with the initial autonomic status and the predominance of the parasympathetic nervous system as well as with clinical markers.

Leptin: Master Regulator of Biological Functions that Affects Breathing

Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleep-disordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin's actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesity-induced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO₂ sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, "leptin resistance" in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. © 2020 American Physiological Society. Compr Physiol 10:1047-1083, 2020.

[Adolescent obstructive sleep apnoea syndrome: Characteristics and treatment]

Although the prevalence of the obstructive sleep apnoea syndrome (OSAS) is high in adolescents, studies pertaining to adolescent OSAS are less numerous than childhood studies. Cases of adolescent OSAS may consist of residual OSAS after adenotonsillectomy, but most often are de novo cases. Major pathophysiological factors are weight excess or even high-grade obesity, and the association of upper airway narrowing and tonsillar hypertrophy (pharyngeal, palatal or even lingual). ENT and systematic orthodontic assessments are the main points. In case of predisposing factors such as dental, occlusal or dento-facial abnormalities, a specific orthodontic treatment can be discussed. First line treatment is surgical adenotonsillectomy; surgical reduction of the lingual tonsils is seldom required. CPAP treatment may be indicated in the case of severe comorbidities (craniofacial malformations, neuromuscular diseases…) or in obese adolescents with severe residual OSAS. Treatment of adolescent OSAS has to be comprehensive and multidisciplinary, taking into account the specific treatments of obesity and abnormal sleep/wake rhythms.

Abnormalities in autonomic function in obese boys at-risk for insulin resistance and obstructive sleep apnea

STUDY OBJECTIVES

Current evidence in adults suggests that, independent of obesity, obstructive sleep apnea (OSA) can lead to autonomic dysfunction and impaired glucose metabolism, but these relationships are less clear in children. The purpose of this study was to investigate the associations among OSA, glucose metabolism, and daytime autonomic function in obese pediatric subjects.

METHODS

Twenty-three obese boys participated in: overnight polysomnography; a frequently sampled intravenous glucose tolerance test; and recordings of spontaneous cardiorespiratory data in both the supine (baseline) and standing (sympathetic stimulus) postures.

RESULTS

Baseline systolic blood pressure and reactivity of low-frequency heart rate variability to postural stress correlated with insulin resistance, increased fasting glucose, and reduced beta-cell function, but not OSA severity. Baroreflex sensitivity reactivity was reduced with sleep fragmentation, but only for subjects with low insulin sensitivity and/or low first-phase insulin response to glucose.

CONCLUSIONS

These findings suggest that vascular sympathetic activity impairment is more strongly affected by metabolic dysfunction than by OSA severity, while blunted vagal autonomic function associated with sleep fragmentation in OSA is enhanced when metabolic dysfunction is also present.

OSA and Cardiovascular Risk in Pediatrics

OSA occurs in approximately 1% to 5% of children in the United States. Long-term cardiovascular risks associated with OSA in the adult population are well documented. Although changes in BP regulation occur in children with OSA, the pathways leading to chronic cardiovascular risks of OSA in children are less clear. Risk factors associated with cardiovascular disease in adult populations could carry the same future risk for children. It is imperative to determine whether known mechanisms of cardiovascular diseases in adults are like those that lead to pediatric disease. Early pathophysiologic changes may lead to a lifetime burden of cardiovascular disease and early mortality. With this perspective in mind, our review discusses pathways leading to cardiovascular pathology in children with OSA and provides a comprehensive overview of recent research findings related to cardiovascular sequelae in the pediatric population.

Prothrombotic state in children with obstructive sleep apnea

OBJECTIVE

Increased blood coagulation might be one important mechanism linking obstructive sleep apnea (OSA) with cardiovascular diseases. We tested the association between several hemostatic parameters and sleep breathing-related variables in a representative pediatric population with a clinical suspicion of OSA.

METHODS

Polysomnography was performed in 152 snoring children to diagnose OSA. Anthropometric and clinical data were registered and venous blood samples were collected for the measurement of platelet count, plateletcrit, platelet distribution width (PDW), mean platelet volume (MPV), prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and C-reactive protein.

RESULTS

Children with OSA had significantly higher platelet count, plateletcrit and PDW compared with those without OSA. After controlling for the anthropometric characteristics (age, gender, body mass index (BMI) z-score), platelet count negatively correlated with minimum SaO₂ while the plateletcrit correlated with time with SaO₂ <90% and MPV correlated with apnea-hypopnea index. PT and PT international normalized ratio correlated with mean SaO₂ and aPTT correlated with the oxygen desaturation index.

CONCLUSION

Our findings suggest that different OSA-related effects may be factors contributing to an enhanced coagulability in pediatric OSA. Measures reflecting apnea severity and disrupted sleep were associated with clotting factor changes independent of covariates affecting hemostatic function.

Electrocardiographic variables in children with syndromic craniosynostosis and primary snoring to mild obstructive sleep apnea: significance of identifying respiratory arrhythmia during sleep

BACKGROUND

In the spectrum of children with symptomatic sleep disordered breathing (SDB), some individuals - such as those with upper airway resistance syndrome (UARS) - do not have abnormalities on polysomnography (PSG). In this study we have assessed whether assessment of respiratory arrhythmia (RA) and heart rate variability (HRV) analysis helps in management of children with syndromic craniosynostosis and none-to-mild obstructive sleep apnea (OSA).

METHODS

Prospective cohort study in children aged 1-18 years old with syndromic craniosynostosis. Children were selected for HRV analysis from the ECG if their obstructive apnea-hypopnea index (oAHI) was between zero and five per hour (ie, oAHI ≤5/hour). Subjects were divided into groups based on the presence or absence of respiratory arrhythmia (with or without RA respectively) using the electrocardiogram (ECG). The main analysis included studying the relationship between RA and HRV, symptoms, interventions, and sleep architecture.

RESULTS

We identified 42 patients with, at worst, mild OSA. We found higher parasympathetic control and higher total power in children with RA during the non-rapid eye movement (non-REM) sleep. Children with RA also have a relatively higher percentage of paradoxical breathing during non-REM sleep (P = 0.042). Intracranial hypertension was distributed equally between groups. Last, RA patients showed increased parasympathetic activity that further increased in non-REM sleep.

CONCLUSION

In syndromic craniosynostosis cases with SDB and PSG showing oAHI ≤5/hour, the presence of RA may indicate subsequent need for treatment interventions, and a trend toward higher occurrence of clinical symptoms. ECG analyses of HRV variables in subjects with RA demonstrate increased parasympathetic activity and total power. Such findings may add to the diagnosis of apparently asymptomatic children.