Cortical thickness and hippocampal volume in adolescent children with obstructive sleep apnea

STUDY OBJECTIVES

Intermittent hypoxia and sleep fragmentation due to obstructive sleep apnea (OSA) may contribute to oxidative tissue damage and apoptotic neuronal cell death, inflammation, and intracellular edema in the brain. We examined whether OSA in overweight and obese adolescent children is associated with cortical thickness and hippocampal structure compared to overweight and obese controls and whether OSA severity is associated with measures of brain integrity.

METHODS

We calculated cortical thickness and hippocampal subfield volumes from T1-weighted images of 45 controls (age 15.43 ± 1.73 years, 21 male) and 53 adolescent children with OSA (age 15.26 ± 1.63 years, 32 male) to investigate the association of childhood OSA with the alteration of cortical structure and hippocampal subfield structural changes. In addition, we investigated the correlation between OSA severity and cortical thickness or hippocampal subfield volume using Pearson's correlation analysis.

RESULTS

We found cortical thinning in the right superior parietal area of adolescent children with OSA (cluster size 32.29 mm2, cluster-wise corrected p-value = .030) that was negatively correlated with apnea-hypopnea index (AHI) (R=-0.27, p-value = .009) and arousal index (R=-0.25, p-value = .014). In addition, the volume of the right subiculum-head area of the hippocampus of adolescent children with OSA was larger than controls (0.19 ± 0.02 ml vs. 0.18 ± 0.02 ml, β = 13.79, false discovery rate corrected p-value = .044), and it was positively correlated with AHI (R = 0.23, p-value = .026) and arousal index (R = 0.31, p-value = .002).

CONCLUSIONS

Our findings provide evidence for OSA-associated brain structure alterations in adolescent children prior to the onset of treatment that likely have important implications for timely intervention and continued monitoring of health outcomes.

Severe central sleep apnea in a child with biallelic variants in NALCN

The sodium leak channel, nonselective (NALCN), is necessary for the proper function of the neurons that play an important role in the sleep-wake cycle and regulation of breathing patterns during wakefulness and sleep. We report a 38-month-old male with developmental delay, hypotonia, and severe central sleep apnea with periodic breathing requiring noninvasive ventilation during sleep, who was found to have novel biallelic pathogenic variants in NALCN. A review of the literature illustrates 17 additional children with biallelic variants in the NALCN gene. The clinical and sleep manifestations of these children are discussed.

CITATION

Maselli K, Park H, Breilyn MS, Arens R. Severe central sleep apnea in a child with biallelic variants in NALCN. J Clin Sleep Med. 2022;18(10):2507-2513.

Respiratory Distress: Three Patient Cases

As mentioned in the January 2022 Pediatrics in Review Commentary, we now present three patients who have a common chief complaint followed by 5 questions for CME credit. All three cases have discussions on presentation, the differential diagnosis, and management that collectively serve as a Review article. The common theme here is that all three patients have difficulty breathing. We hope you will enjoy this review format.

Altered cortical structure network in children with obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is characterized by recurrent airway collapse during sleep, resulting in intermittent hypoxia and sleep fragmentation that may contribute to alternations in brain structure and function. We hypothesized that OSA in children reorganizes and alters cortical structure, which can cause changes in cortical thickness correlation between brain regions across subjects.

METHODS

We constructed cortical structure networks based on cortical thickness measurements from 41 controls (age 15.54 ± 1.66 years, male 19) and 50 children with OSA (age 15.32 ± 1.65 years, male 29). The global (clustering coefficient [CC], path length, and small-worldness) and regional (nodal betweenness centrality, NBC) network properties and hub region distributions were examined between groups.

RESULTS

We found increased CCs in OSA compared to controls across a wide range of network densities (p-value < .05) and lower NBC area under the curve in left caudal anterior cingulate, left caudal middle frontal, left fusiform, left transverse temporal, right pars opercularis, and right precentral gyri (p-value < .05). In addition, while most of the hub regions were the same between groups, the OSA group had fewer hub regions and a different hub distribution compared to controls.

CONCLUSIONS

Our findings suggest that children with OSA exhibit altered global and regional network characteristics compared to healthy controls. Our approach to the investigation of cortical structure in children with OSA could prove useful in understanding the etiology of OSA-related brain functional disorders.

Insulin sensitivity and obstructive sleep apnea in adolescents with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) in adults is linked with insulin resistance (IR) and obstructive sleep apnea (OSA). However, less is known about these associations in adolescents.

METHODS

We studied 3 groups of adolescents: 27 obese PCOS (OPCOS) (ages 13-21)11 normal-weight PCOS (NPCOS) (ages 13-21 years), and 8 healthy controls (ages 18-21 years). A hyperinsulinemic euglycemic clamp study was performed in all groups to determine IR by insulin sensitivity (M/I). Polysomnography was performed to assess for OSA in OPCOS and NPCOS groups. We compared indices of IR among all groups and OSA among OPCOS, and NPCOS.

RESULTS

We noted that OPCOS and NPCOS and controls differed significantly in their IR. M/I was significantly lower in OPCOS vs. controls (p=0.0061), and also lower for NPCOS vs control but this approached but did not reach statistical significance (p=0.084). In addition, none of the NPCOS subjects had OSA compared to 42% of OPCOS (p=0.03).

CONCLUSIONS

Our study suggests OPCOS adolescents have increased IR compared to controls and NPCOS subjects. Higher IR for NPCOS vs controls approached but did not reach statistical significance. Larger studies are needed. In addition, adolescents with OPCOS are at a high risk for OSA.

Automatic upper airway segmentation in static and dynamic MRI via anatomy-guided convolutional neural networks

PURPOSE

Upper airway segmentation on MR images is a prerequisite step for quantitatively studying the anatomical structure and function of the upper airway and surrounding tissues. However, the complex variability of intensity and shape of anatomical structures and different modes of image acquisition commonly used in this application makes automatic upper airway segmentation challenging. In this paper, we develop and test a comprehensive deep learning-based segmentation system for use on MR images to address this problem.

MATERIALS AND METHODS

In our study, both static and dynamic MRI data sets are utilized, including 58 axial static 3D MRI studies, 22 mid-retropalatal dynamic 2D MRI studies, 21 mid-retroglossal dynamic 2D MRI studies, 36 mid-sagittal dynamic 2D MRI studies, and 23 isotropic dynamic 3D MRI studies, involving a total of 160 subjects and over 20 000 MRI slices. Samples of static and 2D dynamic MRI data sets were randomly divided into training, validation, and test sets by an approximate ratio of 5:2:3. Considering that the variability of annotation data among 3D dynamic MRIs was greater than for other MRI data sets, we increased the ratio of training data for these data to improve the robustness of the model. We designed a unified framework consisting of the following procedures. For static MRI, a generalized region-of-interest (GROI) strategy is applied to localize the partitions of nasal cavity and other portions of upper airway in axial data sets as two separate subobjects. Subsequently, the two subobjects are segmented by two separate 2D U-Nets. The two segmentation results are combined as the whole upper airway structure. The GROI strategy is also applied to other MRI modes. To minimize false-positive and false-negative rates in the segmentation results, we employed a novel loss function based explicitly on these rates to train the segmentation networks. An inter-reader study is conducted to test the performance of our system in comparison to human variability in ground truth (GT) segmentation of these challenging structures.

RESULTS

The proposed approach yielded mean Dice coefficients of 0.84±0.03, 0.89±0.13, 0.84±0.07, and 0.86±0.05 for static 3D MRI, mid-retropalatal/mid-retroglossal 2D dynamic MRI, mid-sagittal 2D dynamic MRI, and isotropic dynamic 3D MRI, respectively. The quantitative results show excellent agreement with manual delineation results. The inter-reader study results demonstrate that the segmentation performance of our approach is statistically indistinguishable from manual segmentations considering the inter-reader variability in GT.

CONCLUSIONS

The proposed method can be utilized for routine upper airway segmentation from static and dynamic MR images with high accuracy and efficiency. The proposed approach has the potential to be employed in other dynamic MRI-related applications, such as lung or heart segmentation.

Upper airway effective compliance during wakefulness and sleep in obese adolescents studied via two-dimensional dynamic MRI and semiautomated image segmentation

Novel biomarkers of upper airway biomechanics may improve diagnosis of obstructive sleep apnea syndrome (OSAS). Upper airway effective compliance (EC), the slope of cross-sectional area versus pressure estimated using computational fluid dynamics (CFD), correlates with apnea-hypopnea index (AHI) and critical closing pressure (P_crit). The study objectives are to develop a fast, simplified method for estimating EC using dynamic MRI and physiological measurements and to explore the hypothesis that OSAS severity correlates with mechanical compliance during wakefulness and sleep. Five obese children with OSAS and five control subjects with obesity aged 12-17 yr underwent anterior rhinomanometry, polysomnography, and dynamic MRI with synchronized airflow measurement during wakefulness and sleep. Airway cross section in retropalatal and retroglossal section images was segmented using a novel semiautomated method that uses optimized singular value decomposition (SVD) image filtering and k-means clustering combined with morphological operations. Pressure was estimated using rhinomanometry Rohrer's coefficients and flow rate, and EC was calculated from the area-pressure slope during five normal breaths. Correlations between apnea-hypopnea index (AHI), EC, and cross-sectional area (CSA) change were calculated using Spearman's rank correlation. The semiautomated method efficiently segmented the airway with average Dice Coefficient above 89% compared with expert manual segmentation. AHI correlated positively with EC at the retroglossal site during sleep (r_s = 0.74, P = 0.014) and with change of EC from wake to sleep at the retroglossal site (r_s = 0.77, P = 0.01). CSA change alone did not correlate significantly with AHI. EC, a mechanical biomarker which includes both CSA change and pressure variation, is a potential diagnostic biomarker for studying and managing OSAS.NEW & NOTEWORTHY This study investigated the dynamics of the upper airway at retropalatal and retroglossal sites during wakefulness and sleep by evaluating the effective compliance (EC) of each site and its correlation with apnea-hypopnea index (AHI) using novel semiautomated image processing. AHI correlated significantly with retroglossal EC during sleep and change of retroglossal EC from wake to sleep. The results suggest EC as a promising noninvasive diagnostic marker for estimating the mechanical properties of various upper airway regions in patients with OSAS.

Prevalence of elevated right ventricular pressure in children with obstructive sleep apnea syndrome undergoing pulmonary hypertension screening

STUDY OBJECTIVES

Our objective was to determine the prevalence of elevated right ventricular pressure (RVP) as a surrogate marker for pulmonary hypertension (PH) in children with obstructive sleep apnea syndrome (OSAS) undergoing echocardiography.

METHODS

Retrospective chart review of children age 2-21 years diagnosed with OSAS by an overnight polysomnogram (PSG) who underwent cardiac echocardiogram to screen for PH within 6 months of PSG in a tertiary inner-city pediatric hospital. The primary outcome was elevated RVP defined by estimated RVP ≥ 25 mm Hg above right atrial pressure or ventricular septal configuration consistent with elevated RVP.

RESULTS

A total of 174 children were included. The median (interquartile range [IQR]) age was 8.9 (5.5-13.1) years with 59.2% male, 41.4% Hispanic, and 25.9% non-Hispanic Black. The prevalence of obesity was 72.0% and severe or very severe OSAS was present in 93.1%. The median (IQR) apnea-hypopnea index was 28.3 events/h (18.8-52.7 events/h). Seven children (4.0%) had elevated RVP. There was no association between elevated RVP and age, sex, race, BMI percentile, apnea-hypopnea index (AHI), oxygen nadir, or severe (AHI ≥ 10) OSAS.

CONCLUSIONS

Elevated RVP was rare and was not associated with OSAS severity. The prevalence in this cohort is higher than the prevalence of PH noted in similar studies (0-1.8%), which may be related to differences in methodology or unassessed cohort characteristics. Further effort to determine the optimal role for PH screening in pediatric OSAS is needed.

Effect of sleep on upper airway dynamics in obese adolescents with obstructive sleep apnea syndrome

STUDY OBJECTIVES

The biomechanical basis of obstructive sleep apnea syndrome (OSAS) may influence upper airway dynamics. In this study, we investigate dynamic changes during respiration in wakefulness and sleep in obese adolescents with and without OSAS.

METHODS

Respiratory-gated dynamic magnetic resonance imaging (MRI) at the retropalatal and retroglossal regions was performed with simultaneous measurement of SpO2 and nasal-oral mask airflow and pressure. Airway cross-sectional area (CSA) was determined using AMIRA. Percent change in CSA was calculated from five continuous tidal breaths in states of wakefulness and sleep. Mixed effects models were used to evaluate interactions between group (OSAS/control), site (retropalatal/retroglossal), and stage (wake/sleep).

RESULTS

We studied 24 children with OSAS (mean age 15.49 ± 2.00 years, mean apnea-hypopnea index [AHI] 16.53 ± 8.72 events/h) and 19 controls (mean age 14.86 ± 1.75 years, mean AHI 2.12 ± 1.69 events/h). Groups were similar in age, sex, height, weight, and BMI Z-score. Participants with OSAS had a 48.17% greater increase in percent change of airway CSA during sleep than controls (p < 0.0001), while there was no difference between groups during wakefulness (p = 0.6589). Additionally, participants with OSAS had a 48.80% increase in percent change of airway CSA during sleep as compared with wakefulness (p < 0.0001), whereas no such relationship was observed in controls (p = 0.5513).

CONCLUSIONS

This study demonstrates significant effects of sleep on upper airway dynamics in obese children with OSAS. Dynamic MRI with physiological data can potentially provide further insight into the biomechanical basis of OSAS and assist in more effective management.

Segmentation of 4D images via space-time neural networks

Medical imaging techniques currently produce 4D images that portray the dynamic behaviors and phenomena associated with internal structures. The segmentation of 4D images poses challenges different from those arising in segmenting 3D static images due to different patterns of variation of object shape and appearance in the space and time dimensions. In this paper, different network models are designed to learn the pattern of slice-to-slice change in the space and time dimensions independently. The two models then allow a gamut of strategies to actually segment the 4D image, such as segmentation following just the space or time dimension only, or following first the space dimension for one time instance and then following all time instances, or vice versa, etc. This paper investigates these strategies in the context of the obstructive sleep apnea (OSA) application and presents a unified deep learning framework to segment 4D images. Because of the sparse tubular nature of the upper airway and the surrounding low-contrast structures, inadequate contrast resolution obtainable in the magnetic resonance (MR) images leaves many challenges for effective segmentation of the dynamic airway in 4D MR images. Given that these upper airway structures are sparse, a Dice coefficient (DC) of ~0.88 for their segmentation based on our preferred strategy is similar to a DC of >0.95 for large non-sparse objects like liver, lungs, etc., constituting excellent accuracy.

Evaluation and Management of Children with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is a common pediatric disorder characterized by recurrent events of partial or complete upper airway obstruction during sleep which result in abnormal ventilation and sleep pattern. OSAS in children is associated with neurobehavioral deficits and cardiovascular morbidity which highlights the need for prompt recognition, diagnosis, and treatment. The purpose of this state-of-the-art review is to provide an update on the evaluation and management of children with OSAS with emphasis on children with complex medical comorbidities and those with residual OSAS following first-line treatment. Proposed treatment strategies reflecting recommendations from a variety of professional societies are presented. All children should be screened for OSAS and those with typical symptoms (e.g., snoring, restless sleep, and daytime hyperactivity) or risk factors (e.g., neurologic, genetic, and craniofacial disorders) should undergo further evaluation including referral to a sleep specialist or pediatric otolaryngologist and overnight polysomnography, which provides a definitive diagnosis. A cardiology and/or endocrinology evaluation should be considered in high-risk children. For the majority of children, first-line treatment is tonsillectomy with or without adenoidectomy; however, some children exhibit multiple levels of airway obstruction and may require additional evaluation and management. Anti-inflammatory medications, weight loss, and oral appliances may be appropriate in select cases, particularly for mild OSAS. Following initial treatment, all children should be monitored for residual symptoms and polysomnography may be repeated to identify persistent disease, which can be managed with positive airway pressure ventilation and additional surgical approaches if required.

The relationship of hypertension with obesity and obstructive sleep apnea in adolescents

OBJECTIVES

To assess the independent relationships of obesity and obstructive sleep apnea (OSA) with hypertension/elevated blood pressure (EBP) in adolescent patients.

STUDY DESIGN

A retrospective cohort analysis was performed on 501 patients (age 13-21 years) with three separate blood pressure measurements within 6 months of polysomnography. EBP was defined as average systolic blood pressure (SBP) ≤120 mm Hg; obesity as body mass index Z-score ≤1.65; and OSA as obstructive apnea-hypopnea index <1. Pearson correlations and multivariable analyses were performed to assess the independent effects of the apnea-hypopnea index and body mass index Z-score on SBP.

RESULTS

Of 501 patients (mean age 16 ± 2 years), 246 (49%) were male. OSA was present in 329 (66%) patients, obesity in 337 (67%), and EBP in 262 (52%). EBP was present in 70% of obese adolescents and 60% of adolescents with OSA. Univariable correlation showed a significant relationship between SBP, body mass index Z-score, and apnea-hypopnea index. Multivariable linear regression analysis showed blood pressure was significantly associated with body mass index Z-score (β = .46; P < .01), age (β = .25; P < .01), and height Z-score (β = .14; P < .01), but not apnea-hypopnea index (β = .01; P = .72).

CONCLUSIONS

The relationship between OSA and EBP in adolescents is most closely associated with the degree of obesity. Further studies are needed to assess the effect of the treatment of obesity and OSA on blood pressure in adolescents.

Depressive symptomatology in school-aged children with obstructive sleep apnea syndrome: incidence, demographic factors, and changes following a randomized controlled trial of adenotonsillectomy

Study Objectives

Depressive symptoms following adenotonsillectomy (AT) relative to controls were examined in children with obstructive sleep apnea syndrome (OSAS).

Methods

The Childhood Adenotonsillectomy Trial (CHAT) multisite study examined the impact of AT in 453 children aged 5 to 9.9 years with polysomnographic evidence of OSAS without prolonged desaturation, randomized to early adenotonsillectomy (eAT) or watchful waiting with supportive care (WWSC). One hundred seventy-six children (eAT n = 83; WWSC n = 93) with complete evaluations for depressive symptomatology between baseline and after a 7-month intervention period were included in this secondary analysis.

Results

Exact binomial test assessed proportion of depressive symptomatology relative to norms, while effects of AT and OSAS resolution were assessed through linear quantile mixed-models. Treatment group assignment did not significantly impact depression symptoms, although self-reported depression symptoms improved over time (p < 0.001). Resolution of OSAS symptoms demonstrated a small interaction effect in an unexpected direction, with more improvement in parent ratings of anxious/depressed symptoms for children without resolution (p = 0.030). Black children reported more severe depressive symptoms (p = 0.026) and parents of overweight/obese children reported more withdrawn/depressed symptoms (p = 0.004). Desaturation nadir during sleep was associated with self-report depressed (r = -0.17, p = 0.028), parent-reported anxious/depressed (r = -0.15, p = 0.049), and withdrawn/depressed (r = -0.24, p = 0.002) symptoms.

Conclusions

Increased risk for depressed and withdrawn/depressed symptoms was detected among children with OSAS, and different demographic variables contributed to risk in self-reported and parent-reported depression symptoms. Arterial oxygen desaturation nadir during sleep was strongly associated with depressed symptoms. However, despite improvements in child-reported depressed symptoms over time, changes were unrelated to either treatment group or OSAS resolution status.

Trials Registration

Childhood Adenotonsillectomy Study for Children with OSAS (CHAT), https://clinicaltrials.gov/show/NCT00560859, NCT00560859.

Association Between Periodic Limb Movements in Sleep and Cerebrovascular Changes in Children With Sickle Cell Disease

STUDY OBJECTIVES

Periodic limb movements (PLMs) have been associated with increased risk of stroke, but there is currently scarce research exploring this relationship in the setting of sickle cell disease (SCD). The aim of this study was to explore whether increased PLMs in children with SCD are associated with increased risk of cerebrovascular disease and to determine if there are any clinical or laboratory differences between children with SCD with elevated periodic limb movement index (PLMI) versus those with normal PLMI.

METHODS

This study is a comprehensive review of medical records of 129 children with SCD (aged ≤ 18 years) who had undergone polysomnography for evaluation of sleep-disordered breathing.

RESULTS

Elevated PLMI (PLMI > 5 events/h) was present in 42% (54/129) of children with SCD. Children with elevated PLMI were found to have higher percentage of hemoglobin S, lower total iron, higher arousal index and tendency toward elevated transcranial Doppler velocity (P = .063, odds ratio = 3.9, 95% CI 0.93-16.22). While association between elevated PLMI and isolated cerebrovascular stenosis (P = .050, odds ratio 5.6, 95% CI 1.0-31.10) trended toward significance, there was significantly greater proportion of children with elevated PLMI who had cerebrovascular stenosis with Moyamoya disease (P = .046) as demonstrated by magnetic resonance imaging (MRI).

CONCLUSIONS

The prevalence of elevated PLMI in children with SCD was higher than in previously published data. Elevated PLMI was significantly associated with greater rates of cerebrovascular disease as detected by MRI.

Admixture mapping identifies novel loci for obstructive sleep apnea in Hispanic/Latino Americans

Obstructive sleep apnea (OSA) is a common disorder associated with increased risk of cardiovascular disease and mortality. Its prevalence and severity vary across ancestral background. Although OSA traits are heritable, few genetic associations have been identified. To identify genetic regions associated with OSA and improve statistical power, we applied admixture mapping on three primary OSA traits [the apnea hypopnea index (AHI), overnight average oxyhemoglobin saturation (SaO2) and percentage time SaO2 < 90%] and a secondary trait (respiratory event duration) in a Hispanic/Latino American population study of 11 575 individuals with significant variation in ancestral background. Linear mixed models were performed using previously inferred African, European and Amerindian local genetic ancestry markers. Global African ancestry was associated with a lower AHI, higher SaO2 and shorter event duration. Admixture mapping analysis of the primary OSA traits identified local African ancestry at the chromosomal region 2q37 as genome-wide significantly associated with AHI (P < 5.7 × 10-5), and European and Amerindian ancestries at 18q21 suggestively associated with both AHI and percentage time SaO2 < 90% (P < 10-3). Follow-up joint ancestry-SNP association analyses identified novel variants in ferrochelatase (FECH), significantly associated with AHI and percentage time SaO2 < 90% after adjusting for multiple tests (P < 8 × 10-6). These signals contributed to the admixture mapping associations and were replicated in independent cohorts. In this first admixture mapping study of OSA, novel associations with variants in the iron/heme metabolism pathway suggest a role for iron in influencing respiratory traits underlying OSA.

Associations of variants In the hexokinase 1 and interleukin 18 receptor regions with oxyhemoglobin saturation during sleep

Sleep disordered breathing (SDB)-related overnight hypoxemia is associated with cardiometabolic disease and other comorbidities. Understanding the genetic bases for variations in nocturnal hypoxemia may help understand mechanisms influencing oxygenation and SDB-related mortality. We conducted genome-wide association tests across 10 cohorts and 4 populations to identify genetic variants associated with three correlated measures of overnight oxyhemoglobin saturation: average and minimum oxyhemoglobin saturation during sleep and the percent of sleep with oxyhemoglobin saturation under 90%. The discovery sample consisted of 8,326 individuals. Variants with p < 1 × 10(-6) were analyzed in a replication group of 14,410 individuals. We identified 3 significantly associated regions, including 2 regions in multi-ethnic analyses (2q12, 10q22). SNPs in the 2q12 region associated with minimum SpO2 (rs78136548 p = 2.70 × 10(-10)). SNPs at 10q22 were associated with all three traits including average SpO2 (rs72805692 p = 4.58 × 10(-8)). SNPs in both regions were associated in over 20,000 individuals and are supported by prior associations or functional evidence. Four additional significant regions were detected in secondary sex-stratified and combined discovery and replication analyses, including a region overlapping Reelin, a known marker of respiratory complex neurons.These are the first genome-wide significant findings reported for oxyhemoglobin saturation during sleep, a phenotype of high clinical interest. Our replicated associations with HK1 and IL18R1 suggest that variants in inflammatory pathways, such as the biologically-plausible NLRP3 inflammasome, may contribute to nocturnal hypoxemia.

The role of CD27-CD70-mediated T cell co-stimulation in vasculogenesis, arteriogenesis and angiogenesis

BACKGROUND

T cells have a distinctive role in neovascularization, which consists of arteriogenesis and angiogenesis under pathological conditions and vasculogenesis under physiological conditions. However, the role of co-stimulation in T cell activation in neovascularization has yet to be established. The aim of this study was to investigate the role T cell co-stimulation and inhibition in angiogenesis, arteriogenesis and vasculogenesis.

METHODS AND RESULTS

Hind limb ischemia was induced by double ligation of the left femoral artery in mice and blood flow recovery was measured with Laser Doppler Perfusion Imaging in control, CD70^-/-, CD80/86^-/-, CD70/80/86^-/- and CTLA4^+/- mice. Blood flow recovery was significantly impaired in mice lacking CD70 compared to control mice, but was similar in CD80/86^-/-, CTLA4^+/- and control mice. Mice lacking CD70 showed impaired vasculogenesis, since the number of pre-existing collaterals was reduced as observed in the pia mater compared to control mice. In vitro an impaired capability of vascular smooth muscle cells (VSMC) to activate T cells was observed in VSMC lacking CD70. Furthermore, CD70^-/-, CD80/86^-/- and CD70/80/86^-/- mice showed reduced angiogenesis in the soleus muscle 10 days after ligation. Arteriogenesis was also decreased in CD70^-/- compared to control mice 10 and 28 days after surgery.

CONCLUSIONS

The present study is the first to describe an important role for T cell activation via co-stimulation in angiogenesis, arteriogenesis and vasculogenesis, where the CD27-CD70 T cell co-stimulation pathway appears to be the most important co-stimulation pathway in pre-existing collateral formation and post-ischemic blood flow recovery, by arteriogenesis and angiogenesis.

Biomechanics of the soft-palate in sleep apnea patients with polycystic ovarian syndrome

Highly compliant tissue supporting the pharynx and low muscle tone enhance the possibility of upper airway occlusion in children with obstructive sleep apnea (OSA). The present study describes subject-specific computational modeling of flow-induced velopharyngeal narrowing in a female child with polycystic ovarian syndrome (PCOS) with OSA and a non-OSA control. Anatomically accurate three-dimensional geometries of the upper airway and soft-palate were reconstructed for both subjects using magnetic resonance (MR) images. A fluid-structure interaction (FSI) shape registration analysis was performed using subject-specific values of flow rate to iteratively compute the biomechanical properties of the soft-palate. The optimized shear modulus for the control was 38 percent higher than the corresponding value for the OSA patient. The proposed computational FSI model was then employed for planning surgical treatment for the apneic subject. A virtual surgery comprising of a combined adenoidectomy, palatoplasty and genioglossus advancement was performed to estimate the resulting post-operative patterns of airflow and tissue displacement. Maximum flow velocity and velopharyngeal resistance decreased by 80 percent and 66 percent respectively following surgery. Post-operative flow-induced forces on the anterior and posterior faces of the soft-palate were equilibrated and the resulting magnitude of tissue displacement was 63 percent lower compared to the pre-operative case. Results from this pilot study indicate that FSI computational modeling can be employed to characterize the mechanical properties of pharyngeal tissue and evaluate the effectiveness of various upper airway surgeries prior to their application.

Multiethnic Meta-Analysis Identifies RAI1 as a Possible Obstructive Sleep Apnea-related Quantitative Trait Locus in Men

Obstructive sleep apnea (OSA) is a common heritable disorder displaying marked sexual dimorphism in disease prevalence and progression. Previous genetic association studies have identified a few genetic loci associated with OSA and related quantitative traits, but they have only focused on single ethnic groups, and a large proportion of the heritability remains unexplained. The apnea-hypopnea index (AHI) is a commonly used quantitative measure characterizing OSA severity. Because OSA differs by sex, and the pathophysiology of obstructive events differ in rapid eye movement (REM) and non-REM (NREM) sleep, we hypothesized that additional genetic association signals would be identified by analyzing the NREM/REM-specific AHI and by conducting sex-specific analyses in multiethnic samples. We performed genome-wide association tests for up to 19,733 participants of African, Asian, European, and Hispanic/Latino American ancestry in 7 studies. We identified rs12936587 on chromosome 17 as a possible quantitative trait locus for NREM AHI in men (N = 6,737; P = 1.7 × 10-8) but not in women (P = 0.77). The association with NREM AHI was replicated in a physiological research study (N = 67; P = 0.047). This locus overlapping the RAI1 gene and encompassing genes PEMT1, SREBF1, and RASD1 was previously reported to be associated with coronary artery disease, lipid metabolism, and implicated in Potocki-Lupski syndrome and Smith-Magenis syndrome, which are characterized by abnormal sleep phenotypes. We also identified gene-by-sex interactions in suggestive association regions, suggesting that genetic variants for AHI appear to vary by sex, consistent with the clinical observations of strong sexual dimorphism.

Effects of Adenotonsillectomy on Parent-Reported Behavior in Children With Obstructive Sleep Apnea

Objectives

The childhood obstructive sleep apnea syndrome (OSAS) is associated with behavioral abnormalities. Studies on the effects of OSAS treatment on behavior are conflicting, with few studies using a randomized design. Further, studies may be confounded by the inclusion of behavioral outcome measures directly related to sleep. The objective of this study was to determine the effect of adenotonsillectomy on behavior in children with OSAS. We hypothesized that surgery would improve behavioral ratings, even when sleep symptom items were excluded from the analysis.

Methods

This was a secondary analysis of Child Behavior Checklist (CBCL) data, with and without exclusion of sleep-specific items, from the Childhood Adenotonsillectomy Trial (CHAT). CBCL was completed by caregivers of 380 children (7.0+1.4 [range 5-9] years) with OSAS randomized to early adenotonsillectomy (eAT) versus 7 months of watchful waiting with supportive care (WWSC).

Results

There was a high prevalence of behavioral problems at baseline; 16.6% of children had a Total Problems score in the clinically abnormal range. At follow-up, there were significant improvements in Total Problems (p < .001), Internalizing Behaviors (p = .04), Somatic Complaints (p = .01), and Thought Problems (p = .01) in eAT vs. WWSC participants. When specific sleep-related question items were removed from the analysis, eAT showed an overall improvement in Total (p = .02) and Other (p = .01) problems. Black children had less improvement in behavior following eAT than white children, but this difference attenuated when sleep-related items were excluded.

Conclusions

This large, randomized trial showed that adenotonsillectomy for OSAS improved parent-rated behavioral problems, even when sleep-specific behavioral issues were excluded from the analysis.

Sleep and Breathing the First Night After Adenotonsillectomy in Obese Children With Obstructive Sleep Apnea

STUDY OBJECTIVES

There are few studies measuring postoperative respiratory complications in obese children with obstructive sleep apnea (OSA) undergoing adenotonsillectomy (AT). These complications are further compounded by perioperative medications. Our objective was to study obese children with OSA for their respiratory characteristics and sleep architecture on the night of AT.

METHODS

This was a prospective study at a tertiary pediatric hospital between January 2009-February 2012. Twenty obese children between 8-17 years of age with OSA and adenotonsillar hypertrophy were recruited. Patients underwent baseline polysomnography (PSG) and AT with or without additional debulking procedures, followed by a second PSG on the night of surgery. Demographic and clinical variables, surgical details, perioperative anesthetics and analgesics, and PSG respiratory and sleep architecture parameters were recorded. Statistical tests included Pearson correlation coefficient for correlation between continuous variables and chi-square and Wilcoxon rank-sum tests for differences between groups.

RESULTS

Baseline PSG showed OSA with mean obstructive apnea-hypopnea index (oAHI) 27.1 ± 22.9, SpO₂ nadir 80.1 ± 7.9%, and sleep fragmentation-arousal index 25.5 ± 22.0. Postoperatively, 85% of patients had abnormal sleep studies similar to baseline, with postoperative oAHI 27.0 ± 34.3 (P = .204), SpO₂ nadir, 82.0 ± 8.7% (P = .462), and arousal index, 24.3 ± 24.0 (P = .295). Sleep architecture was abnormal after surgery, showing a significant decrease in REM sleep (P = .003), and a corresponding increase in N2 (P = .017).

CONCLUSIONS

Obese children undergoing AT for OSA are at increased risk for residual OSA on the night of surgery. Special considerations should be taken for postoperative monitoring and treatment of these children.

COMMENTARY

A commentary on this article appears in this issue on page 775.

Genetic Associations with Obstructive Sleep Apnea Traits in Hispanic/Latino Americans

RATIONALE

Obstructive sleep apnea is a common disorder associated with increased risk for cardiovascular disease, diabetes, and premature mortality. Although there is strong clinical and epidemiologic evidence supporting the importance of genetic factors in influencing obstructive sleep apnea, its genetic basis is still largely unknown. Prior genetic studies focused on traits defined using the apnea-hypopnea index, which contains limited information on potentially important genetically determined physiologic factors, such as propensity for hypoxemia and respiratory arousability.

OBJECTIVES

To define novel obstructive sleep apnea genetic risk loci for obstructive sleep apnea, we conducted genome-wide association studies of quantitative traits in Hispanic/Latino Americans from three cohorts.

METHODS

Genome-wide data from as many as 12,558 participants in the Hispanic Community Health Study/Study of Latinos, Multi-Ethnic Study of Atherosclerosis, and Starr County Health Studies population-based cohorts were metaanalyzed for association with the apnea-hypopnea index, average oxygen saturation during sleep, and average respiratory event duration.

MEASUREMENTS AND MAIN RESULTS

Two novel loci were identified at genome-level significance (rs11691765, GPR83, P = 1.90 × 10-8 for the apnea-hypopnea index, and rs35424364; C6ORF183/CCDC162P, P = 4.88 × 10-8 for respiratory event duration) and seven additional loci were identified with suggestive significance (P < 5 × 10-7). Secondary sex-stratified analyses also identified one significant and several suggestive associations. Multiple loci overlapped genes with biologic plausibility.

CONCLUSIONS

These are the first genome-level significant findings reported for obstructive sleep apnea-related physiologic traits in any population. These findings identify novel associations in inflammatory, hypoxia signaling, and sleep pathways.

An Official American Thoracic Society Clinical Practice Guideline: Pediatric Chronic Home Invasive Ventilation

BACKGROUND

Children with chronic invasive ventilator dependence living at home are a diverse group of children with special health care needs. Medical oversight, equipment management, and community resources vary widely. There are no clinical practice guidelines available to health care professionals for the safe hospital discharge and home management of these complex children.

PURPOSE

To develop evidence-based clinical practice guidelines for the hospital discharge and home/community management of children requiring chronic invasive ventilation.

METHODS

The Pediatric Assembly of the American Thoracic Society assembled an interdisciplinary workgroup with expertise in the care of children requiring chronic invasive ventilation. The experts developed four questions of clinical importance and used an evidence-based strategy to identify relevant medical evidence. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology was used to formulate and grade recommendations.

RESULTS

Clinical practice recommendations for the management of children with chronic ventilator dependence at home are provided, and the evidence supporting each recommendation is discussed.

CONCLUSIONS

Collaborative generalist and subspecialist comanagement is the Medical Home model most likely to be successful for the care of children requiring chronic invasive ventilation. Standardized hospital discharge criteria are suggested. An awake, trained caregiver should be present at all times, and at least two family caregivers should be trained specifically for the child's care. Standardized equipment for monitoring, emergency preparedness, and airway clearance are outlined. The recommendations presented are based on the current evidence and expert opinion and will require an update as new evidence and/or technologies become available.

MR Image Analytics to Characterize the Upper Airway Structure in Obese Children with Obstructive Sleep Apnea Syndrome

Purpose

Quantitative image analysis in previous research in obstructive sleep apnea syndrome (OSAS) has focused on the upper airway or several objects in its immediate vicinity and measures of object size. In this paper, we take a more general approach of considering all major objects in the upper airway region and measures pertaining to their individual morphological properties, their tissue characteristics revealed by image intensities, and the 3D architecture of the object assembly. We propose a novel methodology to select a small set of salient features from this large collection of measures and demonstrate the ability of these features to discriminate with very high prediction accuracy between obese OSAS and obese non-OSAS groups.

Materials and Methods

Thirty children were involved in this study with 15 in the obese OSAS group with an apnea-hypopnea index (AHI) = 14.4 ± 10.7) and 15 in the obese non-OSAS group with an AHI = 1.0 ± 1.0 (p<0.001). Subjects were between 8–17 years and underwent T1- and T2-weighted magnetic resonance imaging (MRI) of the upper airway during wakefulness. Fourteen objects in the vicinity of the upper airways were segmented in these images and a total of 159 measurements were derived from each subject image which included object size, surface area, volume, sphericity, standardized T2-weighted image intensity value, and inter-object distances. A small set of discriminating features was identified from this set in several steps. First, a subset of measures that have a low level of correlation among the measures was determined. A heat map visualization technique that allows grouping of parameters based on correlations among them was used for this purpose. Then, through T-tests, another subset of measures which are capable of separating the two groups was identified. The intersection of these subsets yielded the final feature set. The accuracy of these features to perform classification of unseen images into the two patient groups was tested by using logistic regression and multi-fold cross validation.

Results

A set of 16 features identified with low inter-feature correlation (< 0.36) yielded a high classification accuracy of 96% with sensitivity and specificity of 97.8% and 94.4%, respectively. In addition to the previously observed increase in linear size, surface area, and volume of adenoid, tonsils, and fat pad in OSAS, the following new markers have been found. Standardized T2-weighted image intensities differed between the two groups for the entire neck body region, pharynx, and nasopharynx, possibly indicating changes in object tissue characteristics. Fat pad and oropharynx become less round or more complex in shape in OSAS. Fat pad and tongue move closer in OSAS, and so also oropharynx and tonsils and fat pad and tonsils. In contrast, fat pad and oropharynx move farther apart from the skin object.

Conclusions

The study has found several new anatomic bio-markers of OSAS. Changes in standardized T2-weighted image intensities in objects may imply that intrinsic tissue composition undergoes changes in OSAS. The results on inter-object distances imply that treatment methods should respect the relationships that exist among objects and not just their size. The proposed method of analysis may lead to an improved understanding of the mechanisms underlying OSAS.

Cognitive Effects of Adenotonsillectomy for Obstructive Sleep Apnea

OBJECTIVE

Research reveals mixed evidence for the effects of adenotonsillectomy (AT) on cognitive tests in children with obstructive sleep apnea syndrome (OSAS). The primary aim of the study was to investigate effects of AT on cognitive test scores in the randomized Childhood Adenotonsillectomy Trial.

METHODS

Children ages 5 to 9 years with OSAS without prolonged oxyhemoglobin desaturation were randomly assigned to watchful waiting with supportive care (n = 227) or early AT (eAT, n = 226). Neuropsychological tests were administered before the intervention and 7 months after the intervention. Mixed model analysis compared the groups on changes in test scores across follow-up, and regression analysis examined associations of these changes in the eAT group with changes in sleep measures.

RESULTS

Mean test scores were within the average range for both groups. Scores improved significantly (P < .05) more across follow-up for the eAT group than for the watchful waiting group. These differences were found only on measures of nonverbal reasoning, fine motor skills, and selective attention and had small effects sizes (Cohen's d, 0.20-0.24). As additional evidence for AT-related effects on scores, gains in test scores for the eAT group were associated with improvements in sleep measures.

CONCLUSIONS

Small and selective effects of AT were observed on cognitive tests in children with OSAS without prolonged desaturation. Relative to evidence from Childhood Adenotonsillectomy Trial for larger effects of surgery on sleep, behavior, and quality of life, AT may have limited benefits in reversing any cognitive effects of OSAS, or these benefits may require more extended follow-up to become manifest.

Computational fluid dynamics upper airway effective compliance, critical closing pressure, and obstructive sleep apnea severity in obese adolescent girls

Obstructive sleep apnea syndrome (OSAS) is associated with anatomical abnormalities restricting upper airway size and functional factors decreasing pharyngeal dilator activity in sleep. In this study we hypothesized that OSAS is also associated with altered pharyngeal mechanical compliance during wakefulness. Five OSAS and six control obese girls between 14 and 18 years of age were studied. All underwent polysomnography, critical closing pressure (P_crit) studies, and dynamic MRI of the upper airway during awake tidal breathing. Effective airway compliance was defined as the slope of cross-sectional area vs. average pressure between maximum inspiration and maximum expiration along the pharyngeal airway. Pharyngeal pressure fields were calculated by using image-based computational fluid dynamics and nasal resistance. Spearman correlations were calculated to test associations between apnea-hypopnea index (AHI), P_crit, and airway compliance. Effective compliances in the nasopharynx (C_NP) and velopharynx (C_VP) were lower and negative in OSAS compared with controls: -4.4 vs. 1.9 (mm²/cmH₂O, P = 0.012) and -2.1 vs. 3.9 (mm²/cmH₂O, P = 0.021), respectively, suggesting a strong phasic pharyngeal dilator activity during inspiration in OSAS compared with controls. For all subjects, C_NP and AHI correlated negatively (r_S = -0.69, P = 0.02), and passive P_crit correlated with C_NP (r_S = -0.76, P = 0.006) and with AHI (r_S = 0.86, P = 0.0006). Pharyngeal mechanics obtained during wakefulness could be used to characterize subjects with OSAS. Moreover, negative effective compliance during wakefulness and its correlation to AHI and P_crit suggest that phasic dilator activity of the upper pharynx compensates for negative pressure loads in these subjects.

Intracapsular and Extracapsular Tonsillectomy and Adenoidectomy in Pediatric Obstructive Sleep Apnea

IMPORTANCE

Limited information exists regarding clinical outcomes of children undergoing extracapsular tonsillectomy and adenoidectomy (ETA) or intracapsular tonsillectomy and adenoidectomy (ITA) for treatment of obstructive sleep apnea syndrome (OSAS).

OBJECTIVES

To quantify polysomnography (PSG) and clinical outcomes of ETA and ITA in children with OSAS and to assess the contribution of comorbid conditions of asthma and obesity.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study using medical records at a tertiary pediatrics inner-city hospital. Medical records from 89 children who underwent ETA or ITA between October 1, 2008, and December 31, 2013, were analyzed. The dates of our analysis were January 6, 2014, to April 11, 2014. Inclusion criteria required no evidence of craniofacial or neurological disorders, confirmation of OSAS by PSG within the 2 years before surgery, and a second PSG within the 2 years after surgery.

INTERVENTIONS

Each child underwent ETA or ITA after being evaluated by a pediatric otolaryngologist and obtaining written parental informed consent.

MAIN OUTCOMES AND MEASURES

Main primary outcomes were derived from PSG. Secondary outcomes included treatment failure, defined as residual OSAS with an obstructive apnea-hypopnea index of at least 5 events per hour. Comparisons were made between and within groups. Logistic regression was used to identify factors associated with treatment failure.

RESULTS

Fifty-two children underwent ETA, and 37 children underwent ITA. Children in the ETA group were older (7.5 vs 5.2 years, P = .001) and more obese (60% [31 of 52] vs 30% [11 of 37], P = .004). However, both groups had similar severity of OSAS, with median preoperative obstructive apnea-hypopnea indexes of 17.0 in the ETA group and 24.1 in the ITA group (P = .21), and similar prevalences of asthma (38% [20 of 52] vs 38% [14 of 37]). After surgery, significant improvement was noted on PSG in both groups, with no differences in any clinical outcomes. There was no association between procedure type, age, or body mass index z score and treatment failure. However, in a subset of patients with asthma and obesity, ITA was associated with residual OSAS (odds ratio, 16.5; 95% CI, 1.1-250.2; P = .04).

CONCLUSIONS AND RELEVANCE

Both ETA and ITA are effective modalities to treat OSAS, with comparable surgical outcomes on short-term follow-up. However, when comorbid diagnoses of both asthma and obesity exist, OSAS is likely to be refractory to treatment with ITA compared with ETA.

Minimally interactive segmentation of 4D dynamic upper airway MR images via fuzzy connectedness

PURPOSE

There are several disease conditions that lead to upper airway restrictive disorders. In the study of these conditions, it is important to take into account the dynamic nature of the upper airway. Currently, dynamic magnetic resonance imaging is the modality of choice for studying these diseases. Unfortunately, the contrast resolution obtainable in the images poses many challenges for an effective segmentation of the upper airway structures. No viable methods have been developed to date to solve this problem. In this paper, the authors demonstrate a practical solution by employing an iterative relative fuzzy connectedness delineation algorithm as a tool.

METHODS

3D dynamic images were collected at ten equally spaced instances over the respiratory cycle (i.e., 4D) in 20 female subjects with obstructive sleep apnea syndrome. The proposed segmentation approach consists of the following steps. First, image background nonuniformities are corrected which is then followed by a process to correct for the nonstandardness of MR image intensities. Next, standardized image intensity statistics are gathered for the nasopharynx and oropharynx portions of the upper airway as well as the surrounding soft tissue structures including air outside the body region, hard palate, soft palate, tongue, and other soft structures around the airway including tonsils (left and right) and adenoid. The affinity functions needed for fuzzy connectedness computation are derived based on these tissue intensity statistics. In the next step, seeds for fuzzy connectedness computation are specified for the airway and the background tissue components. Seed specification is needed in only the 3D image corresponding to the first time instance of the 4D volume; from this information, the 3D volume corresponding to the first time point is segmented. Seeds are automatically generated for the next time point from the segmentation of the 3D volume corresponding to the previous time point, and the process continues and runs without human interaction and completes in 10 s for segmenting the airway structure in the whole 4D volume.

RESULTS

Qualitative evaluations performed to examine smoothness and continuity of motions of the entire upper airway as well as its transverse sections at critical anatomic locations indicate that the segmentations are consistent. Quantitative evaluations of the separate 200 3D volumes and the 20 4D volumes yielded true positive and false positive volume fractions around 95% and 0.1%, respectively, and mean boundary placement errors under 0.5 mm. The method is robust to variations in the subjective action of seed specification. Compared with a segmentation approach based on a registration technique to propagate segmentations, the proposed method is more efficient, accurate, and less prone to error propagation from one respiratory time point to the next.

CONCLUSIONS

The proposed method is the first demonstration of a viable and practical approach for segmenting the upper airway structures in dynamic MR images. Compared to registration-based methods, it effectively reduces error propagation and consequently achieves not only more accurate segmentations but also more consistent motion representation in the segmentations. The method is practical, requiring minimal user interaction and computational time.

Association of glucose homeostasis measures with heart rate variability among Hispanic/Latino adults without diabetes: the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

Background

Reduced heart rate variability (HRV), a measure of cardiac autonomic function, is associated with an increased risk of cardiovascular disease (CVD) and mortality. Glucose homeostasis measures are associated with reduced cardiac autonomic function among those with diabetes, but inconsistent associations have been reported among those without diabetes. This study aimed to examine the association of glucose homeostasis measures with cardiac autonomic function among diverse Hispanic/Latino adults without diabetes.

Methods

The Hispanic community Health Study/Study of Latinos (HCHS/SOL; 2008–2011) used two-stage area probability sampling of households to enroll 16,415 self-identified Hispanics/Latinos aged 18–74 years from four USA communities. Resting, standard 12-lead electrocardiogram recordings were used to estimate the following ultrashort-term measures of HRV: RR interval (RR), standard deviation of all normal to normal RR (SDNN) and root mean square of successive differences in RR intervals (RMSSD). Multivariable regression analysis was used to estimate associations between glucose homeostasis measures with HRV using data from 11,994 adults without diabetes (mean age 39 years; 52 % women).

Results

Higher fasting glucose was associated with lower RR, SDNN, and RMSSD. Fasting insulin and the homeostasis model assessment of insulin resistance was negatively associated with RR, SDNN, and RMSSD, and the association was stronger among men compared with women. RMSSD was, on average, 26 % lower in men with higher fasting insulin and 29 % lower in men with lower insulin resistance; for women, the corresponding estimates were smaller at 4 and 9 %, respectively. Higher glycated hemoglobin was associated with lower RR, SDNN, and RMSSD in those with abdominal adiposity, defined by sex-specific cut-points for waist circumference, after adjusting for demographics and medication use. There were no associations between glycated hemoglobin and HRV measures among those without abdominal adiposity.

Conclusions

Impairment in glucose homeostasis was associated with lower HRV in Hispanic/Latino adults without diabetes, most prominently in men and individuals with abdominal adiposity. These results suggest that reduced cardiac autonomic function is associated with metabolic impairments before onset of overt diabetes in certain subgroups, offering clues for the pathophysiologic processes involved as well as opportunity for identification of those at high risk before autonomic control is manifestly impaired.

Prognosis for Spontaneous Resolution of OSA in Children

BACKGROUND

Adenotonsillectomy (AT) is commonly performed for childhood OSA syndrome (OSAS), but little is known about prognosis without treatment.

METHODS

The Childhood Adenotonsillectomy Trial (CHAT) randomized 50% of eligible children with OSAS to a control arm (watchful waiting), with 7-month follow-up symptom inventories, physical examinations, and polysomnography. Polysomnographic and symptomatic resolution were defined respectively by an apnea/hypopnea index (AHI) <2 and obstructive apnea index (OAI) <1 and by an OSAS symptom score (Pediatric Sleep Questionnaire [PSQ]) < 0.33 with ≥ 25% improvement from baseline.

RESULTS

After 194 children aged 5 to 9 years underwent 7 months of watchful waiting, 82 (42%) no longer met polysomnographic criteria for OSAS. Baseline predictors of resolution included lower AHI, better oxygen saturation, smaller waist circumference or percentile, higher-positioned soft palate, smaller neck circumference, and non-black race (each P < .05). Among these, the independent predictors were lower AHI and waist circumference percentile < 90%. Among 167 children with baseline PSQ scores ≥ 0.33, only 25 (15%) experienced symptomatic resolution. Baseline predictors were low PSQ and PSQ snoring subscale scores; absence of habitual snoring, loud snoring, observed apneas, or a household smoker; higher quality of life; fewer attention-deficit/hyperactivity disorder symptoms; and female sex. Only lower PSQ and snoring scores were independent predictors.

CONCLUSIONS

Many candidates for AT no longer have OSAS on polysomnography after 7 months of watchful waiting, whereas meaningful improvement in symptoms is not common. In practice, a baseline low AHI and normal waist circumference, or low PSQ and snoring score, may help identify an opportunity to avoid AT.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00560859; URL: www.clinicaltrials.gov.

Clinical utility of magnetic resonance imaging and ultrasonography for diagnosis of polycystic ovary syndrome in adolescent girls

OBJECTIVE

To evaluate ovarian morphology using three-dimensional magnetic resonance imaging (MRI) in adolescent girls with and without polycystic ovary syndrome (PCOS). Also compare the utility of MRI versus ultrasonography (US) for diagnosis of PCOS.

DESIGN

Cross-sectional study.

SETTING

Urban academic tertiary-care children's hospital.

PATIENT(S)

Thirty-nine adolescent girls with untreated PCOS and 22 age/body mass index (BMI)-matched controls.

INTERVENTION(S)

Magnetic resonance imaging and/or transvaginal/transabdominal US.

MAIN OUTCOME MEASURE(S)

Ovarian volume (OV); follicle number per section (FNPS); correlation between OV on MRI and US; proportion of subjects with features of polycystic ovaries (PCOs) on MRI and US.

RESULT(S)

Magnetic resonance imaging demonstrated larger OV and higher FNPS in subjects with PCOS compared with controls. Within the PCOS group, median OV was 11.9 (7.7) cm(3) by MRI compared with 8.8 (7.8) cm(3) by US. Correlation coefficient between OV by MRI and US was 0.701. Due to poor resolution, FNPS could not be determined by US or compared with MRI. The receiver operating characteristic curve analysis for MRI demonstrated that increasing volume cutoffs for PCOs from 10-14 cm(3) increased specificity from 77%-95%. For FNPS on MRI, specificity increased from 82%-98% by increasing cutoffs from ≥ 12 to ≥ 17. Using Rotterdam cutoffs, 91% of subjects with PCOS met PCO criteria on MRI, whereas only 52% met criteria by US.

CONCLUSION(S)

Ultrasonography measures smaller OV than MRI, cannot accurately detect follicle number, and is a poor imaging modality for characterizing PCOs in adolescents with suspected PCOS. For adolescents in whom diagnosis of PCOS remains uncertain after clinical and laboratory evaluation, MRI should be considered as a diagnostic imaging modality.

The Effect of Adenotonsillectomy for Childhood Sleep Apnea on Cardiometabolic Measures

STUDY OBJECTIVES

Obstructive sleep apnea syndrome (OSAS) has been associated with cardiometabolic disease in adults. In children, this association is unclear. We evaluated the effect of early adenotonsillectomy (eAT) for treatment of OSAS on blood pressure, heart rate, lipids, glucose, insulin, and C-reactive protein. We also analyzed whether these parameters at baseline and changes at follow-up correlated with polysomnographic indices.

DESIGN

Data collected at baseline and 7-mo follow-up were analyzed from a randomized controlled trial, the Childhood Adenotonsillectomy Trial (CHAT).

SETTING

Clinical referral setting from multiple centers.

PARTICIPANTS

There were 464 children, ages 5 to 9.9 y with OSAS without severe hypoxemia.

INTERVENTIONS

Randomization to eAT or Watchful Waiting with Supportive Care (WWSC).

MEASUREMENTS AND RESULTS

There was no significant change of cardiometabolic parameters over the 7-mo interval in the eAT group compared to WWSC group. However, overnight heart rate was incrementally higher in association with baseline OSAS severity (average heart rate increase of 3 beats per minute [bpm] for apnea-hypopnea index [AHI] of 2 versus 10; [standard error = 0.60]). Each 5-unit improvement in AHI and 5 mmHg improvement in peak end-tidal CO2 were estimated to reduce heart rate by 1 and 1.5 bpm, respectively. An increase in N3 sleep also was associated with small reductions in systolic blood pressure percentile.

CONCLUSIONS

There is little variation in standard cardiometabolic parameters in children with obstructive sleep apnea syndrome (OSAS) but without severe hypoxemia at baseline or after intervention. Of all measures, overnight heart rate emerged as the most sensitive parameter of pediatric OSAS severity.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov (#NCT00560859).

Eating behavior by sleep duration in the Hispanic Community Health Study/Study of Latinos

Sleep is an important pillar of health and a modifiable risk factor for diabetes, stroke and obesity. Little is known of diet and sleep patterns of Hispanics/Latinos in the US. Here we examine eating behavior as a function of sleep duration in a sub-sample of 11,888 participants from the Hispanic Community Health Study/Study of Latinos, a community-based cohort study of Hispanics aged 18-74 years in four US cities. Using a cross-sectional probability sample with self-report data on habitual sleep duration and up to two 24-h dietary recalls, we quantified the Alternative Healthy Eating Index (AHEI-2010) score, a measure of diet quality, and intake of selected nutrients related to cardiovascular health. Linear regression models were fit to estimate least-square means of usual nutrient intake of saturated fats, potassium density, fiber, calcium, caffeine and the AHEI-2010 score by sleep duration adjusting for age, sex, Hispanic/Latino background, income, employment status, education, depressive symptomology, and years lived in the US. Distribution of calories over the day and association with sleep duration and BMI were also examined. Short sleepers (≤6 h) had significantly lower intake of potassium, fiber and calcium and long sleepers (≥9 h) had significantly lower intake of caffeine compared to others sleepers after adjusting for covariates. However no difference in the AHEI-2010 score was seen by sleep duration. Significantly more long sleepers, compared to intermediate and short sleepers, reported having ≥30% total daily calories before bedtime. Not consuming a snack or meal within 3 h before bedtime was associated with higher AHEI-2010 scores. These findings identify novel differences in dietary patterns by sleep duration in a Hispanic/Latino cohort in the U.S. CLINICALTRIALS.

GOV IDENTIFIER

NCT02060344.

Pediatric sleep-related breathing disorders: advances in imaging and computational modeling

We understand now that sleep of sufficient length and quality is required for good health. This is particularly true for infants and children, who have the added physiologic task of growth and development, as compared to their adult counterparts. Sleep-related breathing disorders (SRBDs) are common in childhood and if unrecognized and not treated can result in significant morbidity. For example, children with obstructive sleep apnea (OSA) can exhibit behavioral, mood, and learning difficulties. If left untreated, alterations in the function of the autonomic nervous system and a chronic inflammatory state result, contributing to the risk of heart disease, stroke, glucose intolerance, and hypertension in adulthood.

The use of clinical parameters to predict obstructive sleep apnea syndrome severity in children: the Childhood Adenotonsillectomy (CHAT) study randomized clinical trial

IMPORTANCE

It is important to distinguish children with different levels of severity of obstructive sleep apnea syndrome (OSAS) preoperatively using clinical parameters. This can identify children who most need polysomnography (PSG) prior to adenotonsillectomy (AT).

OBJECTIVE

To assess whether a combination of factors, including demographics, physical examination findings, and caregiver reports from questionnaires, can predict different levels of OSAS severity in children.

DESIGN, SETTING, AND PARTICIPANTS

Baseline data from 453 children from the Childhood Adenotonsillectomy (CHAT) study were analyzed. Children 5.0 to 9.9 years of age with PSG-diagnosed OSAS, who were considered candidates for AT, were included.

INTERVENTIONS

Polysomnography for diagnosis of OSAS.

MAIN OUTCOMES AND MEASURES

Linear or logistic regression models were fitted to identify which demographic, clinical, and caregiver reports were significantly associated with the apnea hypopnea index (AHI) and oxygen desaturation index (ODI).

RESULTS

Race (African American), obesity (body mass index z score > 2), and the Pediatric Sleep Questionnaire (PSQ) total score were associated with higher levels of AHI and ODI (P = .05). A multivariable model that included the most significant variables explained less than 3% of the variance in OSAS severity as measured by PSG outcomes. Tonsillar size and Friedman palate position were not associated with increased AHI or ODI. Models that tested for potential effect modification by race or obesity showed no evidence of interactions with any clinical measure, AHI, or ODI (P > .20 for all comparisons).

CONCLUSIONS AND RELEVANCE

This study of more than 450 children with OSAS identifies a number of clinical parameters that are associated with OSAS severity. However, information on demographics, physical findings, and questionnaire responses does not robustly discriminate different levels of OSAS severity.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00560859.

Utility of symptoms to predict treatment outcomes in obstructive sleep apnea syndrome

BACKGROUND AND OBJECTIVES

Polysomnography defines the pathophysiology of obstructive sleep apnea syndrome (OSAS) but does not predict some important comorbidities or their response to adenotonsillectomy. We assessed whether OSAS symptoms, as reflected on the Sleep-Related Breathing Disorders Scale of the Pediatric Sleep Questionnaire (PSQ), may offer clinical predictive value.

METHODS

Baseline and 7-month follow-up data were analyzed from 185 participants (aged 5-9 years with polysomnographically confirmed OSAS) in the surgical treatment arm of the multicenter Childhood Adenotonsillectomy Trial. Associations were assessed between baseline PSQ or polysomnographic data and baseline morbidity (executive dysfunction, behavior, quality of life, sleepiness) or postsurgical improvement.

RESULTS

At baseline, each 1-SD increase in baseline PSQ score was associated with an adjusted odds ratio that was ∼3 to 4 times higher for behavioral morbidity, 2 times higher for reduced global quality of life, 6 times higher for reduced disease-specific quality of life, and 2 times higher for sleepiness. Higher baseline PSQ scores (greater symptom burden) also predicted postsurgical improvement in parent ratings of executive functioning, behavior, quality of life, and sleepiness. In contrast, baseline polysomnographic data did not independently predict these morbidities or their postsurgical improvement. Neither PSQ nor polysomnographic data were associated with objectively assessed executive dysfunction or improvement at follow-up.

CONCLUSIONS

PSQ symptom items, in contrast to polysomnographic results, reflect subjective measures of OSAS-related impairment of behavior, quality of life, and sleepiness and predict their improvement after adenotonsillectomy. Although objective polysomnography is needed to diagnose OSAS, the symptoms obtained during an office visit can offer adjunctive insight into important comorbidities and likely surgical responses.

Complications of adenotonsillectomy for obstructive sleep apnea in school-aged children

INTRODUCTION

Adenotonsillectomy is the treatment of choice for most children with obstructive sleep apnea syndrome, but can lead to complications. Current guidelines recommend that high-risk children be hospitalized after adenotonsillectomy, but it is unclear which otherwise-healthy children will develop post-operative complications. We hypothesized that polysomnographic parameters would predict post-operative complications in children who participated in the Childhood AdenoTonsillectomy (CHAT) study.

METHODS

Children in the CHAT study aged 5-9 years with apnea hypopnea index 2-30/h or obstructive apnea index 1-20/h without comorbidities other than obesity/asthma underwent adenotonsillectomy. Associations between demographic variables and surgical complications were examined with Chi square and Fisher's exact tests. Polysomnographic parameters between subjects with/without complications were compared using Mann-Whitney tests.

RESULTS

Of the 221 children (median apnea hypopnea index 4.7/h, range 1.2-27.7/h; 31% obese), 16 (7%) children experienced complications. 3 (1.4%) children had respiratory complications including pulmonary edema, hypoxemia and bronchospasm. Thirteen (5.9%) had non-respiratory complications, including dehydration (4.5%), hemorrhage (2.3%) and fever (0.5%). There were no statistically significant associations between demographic parameters (gender, race, and obesity) or polysomnographic parameters (apnea hypopnea index, % total sleep time with SpO2<92%, SpO2 nadir, % sleep time with end-tidal CO2>50Torr) and complications.

CONCLUSIONS

This study showed a low risk of post-adenotonsillectomy complications in school-aged healthy children with obstructive apnea although many children met published criteria for admission due to obesity, or polysomnographic severity. In this specific population, none of the polysomnographic or demographic parameters predicted post-operative complications. Further research could identify the patients at greatest risk of post-operative complications.

Obstructive sleep apnea and neurocognitive function in a Hispanic/Latino population

OBJECTIVE

We evaluated the association between obstructive sleep apnea (OSA) and neurocognitive function among community-dwelling Hispanic/Latino individuals in the United States.

METHODS

Cross-sectional analysis of the Hispanic Community Health Study/Study of Latinos middle-aged and older adults, aged 45 to 74 years, with neurocognitive test scores at baseline measurements from 2008 to 2011. Neurocognitive scores were measured using the Word Fluency (WF) Test, the Brief-Spanish English Verbal Learning Test (SEVLT), and the Digit Symbol Substitution (DSS) Test. OSA was defined by the apnea-hypopnea index (AHI). Multivariable linear regression models were fit to evaluate relations between OSA and neurocognitive scores.

RESULTS

The analysis consisted of 8,059 participants, mean age of 56 years, 55% women, and 41% with less than high school education. The mean AHI was 9.0 (range 0-142; normal AHI <5/h). There was an association between the AHI and all 4 neurocognitive test scores: Brief-SEVLT-sum (β = -0.022) and -recall (β = -0.010), WF (β = -0.023), and DSS (β = -0.050) at p < 0.01 that was fully attenuated by age. In the fully adjusted regression model, female sex was a moderating factor between the AHI and WF (β = -0.027, p < 0.10), SVELT-sum (β = -0.37), SVELT-recall (β = -0.010), and DSS (β = -0.061) at p < 0.01.

CONCLUSION

OSA was associated with worse neurocognitive function in a representative sample of Hispanic/Latino women in the United States.

Growth after adenotonsillectomy for obstructive sleep apnea: an RCT

BACKGROUND AND OBJECTIVES

Adenotonsillectomy for obstructive sleep apnea syndrome (OSAS) may lead to weight gain, which can have deleterious health effects when leading to obesity. However, previous data have been from nonrandomized uncontrolled studies, limiting inferences. This study examined the anthropometric changes over a 7-month interval in a randomized controlled trial of adenotonsillectomy for OSAS, the Childhood Adenotonsillectomy Trial.

METHODS

A total of 464 children who had OSAS (average apnea/hypopnea index [AHI] 5.1/hour), aged 5 to 9.9 years, were randomized to Early Adenotonsillectomy (eAT) or Watchful Waiting and Supportive Care (WWSC). Polysomnography and anthropometry were performed at baseline and 7-month follow-up. Multivariable regression modeling was used to predict the change in weight and growth indices.

RESULTS

Interval increases in the BMI z score (0.13 vs. 0.31) was observed in both the WWSC and eAT intervention arms, respectively, but were greater with eAT (P < .0001). Statistical modeling showed that BMI z score increased significantly more in association with eAT after considering the influences of baseline weight and AHI. A greater proportion of overweight children randomized to eAT compared with WWSC developed obesity over the 7-month interval (52% vs. 21%; P < .05). Race, gender, and follow-up AHI were not significantly associated with BMI z score change.

CONCLUSIONS

eAT for OSAS in children results in clinically significant greater than expected weight gain, even in children overweight at baseline. The increase in adiposity in overweight children places them at further risk for OSAS and the adverse consequences of obesity. Monitoring weight, nutritional counseling, and encouragement of physical activity should be considered after eAT for OSAS.

Anterior nasal resistance in obese children with obstructive sleep apnea syndrome

OBJECTIVES/HYPOTHESIS

To evaluate nasal resistance in obese children with and without obstructive sleep apnea syndrome (OSAS), study the correlation between nasal resistance and severity of OSAS using the apnea-hypopnea index (AHI), and examine the association of gender and body mass index (BMI) with this measurement.

STUDY DESIGN

Retrospective analysis.

METHODS

Active anterior rhinomanometry was used to determine anterior nasal resistance (aNR) during wakefulness in the supine position during tidal breathing. Thirty obese children with OSAS (aged 13.8 ± 2.6 years, BMI z score 2.6 ± 0.4) and 32 matched obese controls (aged 13.6 ± 2.3 years, BMI z score 2.4 ± 0.4), were studied. Unpaired t tests and Spearman correlation were performed.

RESULTS

The OSAS group had significantly higher aNR than the non-OSAS group during inspiration (P = .012) and expiration (P = .003). A significant correlation between inspiratory aNR and AHI was found for the OSAS group (r = 0.39, P = .04). The aNR did not correlate with BMI z score or with either gender.

CONCLUSIONS

We noted a higher aNR in obese children with OSAS as compared to obese controls, and the aNR on inspiration correlated significantly with AHI. These findings suggest that a causal or augmentative effect of high inspiratory aNR may exist for obese children who exhibit OSAS.

LEVEL OF EVIDENCE

3b.

Body-wide hierarchical fuzzy modeling, recognition, and delineation of anatomy in medical images

To make Quantitative Radiology (QR) a reality in radiological practice, computerized body-wide Automatic Anatomy Recognition (AAR) becomes essential. With the goal of building a general AAR system that is not tied to any specific organ system, body region, or image modality, this paper presents an AAR methodology for localizing and delineating all major organs in different body regions based on fuzzy modeling ideas and a tight integration of fuzzy models with an Iterative Relative Fuzzy Connectedness (IRFC) delineation algorithm. The methodology consists of five main steps: (a) gathering image data for both building models and testing the AAR algorithms from patient image sets existing in our health system; (b) formulating precise definitions of each body region and organ and delineating them following these definitions; (c) building hierarchical fuzzy anatomy models of organs for each body region; (d) recognizing and locating organs in given images by employing the hierarchical models; and (e) delineating the organs following the hierarchy. In Step (c), we explicitly encode object size and positional relationships into the hierarchy and subsequently exploit this information in object recognition in Step (d) and delineation in Step (e). Modality-independent and dependent aspects are carefully separated in model encoding. At the model building stage, a learning process is carried out for rehearsing an optimal threshold-based object recognition method. The recognition process in Step (d) starts from large, well-defined objects and proceeds down the hierarchy in a global to local manner. A fuzzy model-based version of the IRFC algorithm is created by naturally integrating the fuzzy model constraints into the delineation algorithm. The AAR system is tested on three body regions - thorax (on CT), abdomen (on CT and MRI), and neck (on MRI and CT) - involving a total of over 35 organs and 130 data sets (the total used for model building and testing). The training and testing data sets are divided into equal size in all cases except for the neck. Overall the AAR method achieves a mean accuracy of about 2 voxels in localizing non-sparse blob-like objects and most sparse tubular objects. The delineation accuracy in terms of mean false positive and negative volume fractions is 2% and 8%, respectively, for non-sparse objects, and 5% and 15%, respectively, for sparse objects. The two object groups achieve mean boundary distance relative to ground truth of 0.9 and 1.5 voxels, respectively. Some sparse objects - venous system (in the thorax on CT), inferior vena cava (in the abdomen on CT), and mandible and naso-pharynx (in neck on MRI, but not on CT) - pose challenges at all levels, leading to poor recognition and/or delineation results. The AAR method fares quite favorably when compared with methods from the recent literature for liver, kidneys, and spleen on CT images. We conclude that separation of modality-independent from dependent aspects, organization of objects in a hierarchy, encoding of object relationship information explicitly into the hierarchy, optimal threshold-based recognition learning, and fuzzy model-based IRFC are effective concepts which allowed us to demonstrate the feasibility of a general AAR system that works in different body regions on a variety of organs and on different modalities.

Sleep-disordered breathing in Hispanic/Latino individuals of diverse backgrounds. The Hispanic Community Health Study/Study of Latinos

RATIONALE

Hispanic/Latino populations have a high prevalence of cardiovascular risk factors and may be at risk for sleep-disordered breathing (SDB). An understanding of SDB among these populations is needed given evidence that SDB increases cardiovascular risk.

OBJECTIVES

To quantify SDB prevalence in the U.S. Hispanic/Latino population and its association with symptoms, risk factors, diabetes, and hypertension; and to explore variation by sex and Hispanic/Latino background.

METHODS

Cross-sectional analysis from the baseline examination of the Hispanic Community Health Study/Study of Latinos.

MEASUREMENTS AND MAIN RESULTS

The apnea-hypopnea index (AHI) was derived from standardized sleep tests; diabetes and hypertension were based on measurement and history. The sample of 14,440 individuals had an age-adjusted prevalence of minimal SDB (AHI ≥ 5), moderate SDB (AHI ≥ 15), and severe SDB (AHI ≥ 30) of 25.8, 9.8, and 3.9%, respectively. Only 1.3% of participants reported a sleep apnea diagnosis. Moderate SDB was associated with being male (adjusted odds ratio, 2.7; 95% confidence interval, 2.3-3.1), obese (16.8; 11.6-24.4), and older. SDB was associated with an increased adjusted odds of impaired glucose tolerance (1.7; 1.3-2.1), diabetes (2.3; 1.8-2.9), and hypertension. The association with hypertension varied across background groups with the strongest associations among individuals of Puerto Rican and Central American background.

CONCLUSIONS

SDB is prevalent in U.S. Latinos but rarely associated with a clinical diagnosis. Associations with diabetes and hypertension suggest a large burden of disease may be attributed to untreated SDB, supporting the development and evaluation of culturally relevant detection and treatment approaches.

Computational fluid dynamics endpoints for assessment of adenotonsillectomy outcome in obese children with obstructive sleep apnea syndrome

BACKGROUND

Improvements in obstructive sleep apnea syndrome (OSAS) severity may be associated with improved pharyngeal fluid mechanics following adenotonsillectomy (AT). The study objective is to use image-based computational fluid dynamics (CFD) to model changes in pharyngeal pressures after AT, in obese children with OSAS and adenotonsillar hypertrophy.

METHODS

Three-dimensional models of the upper airway from nares to trachea, before and after AT, were derived from magnetic resonance images obtained during wakefulness, in a cohort of 10 obese children with OSAS. Velocity, pressure, and turbulence fields during peak tidal inspiratory flow were computed using commercial software. CFD endpoints were correlated with polysomnography endpoints before and after AT using Spearman׳s rank correlation (rs).

RESULTS

Apnea hypopnea index (AHI) decreases after AT was strongly correlated with reduction in maximum pressure drop (dPTAmax) in the region where tonsils and adenoid constrict the pharynx (rs=0.78, P=0.011), and with decrease of the ratio of dPTAmax to flow rate (rs=0.82, P=0.006). Correlations of AHI decrease to anatomy, negative pressure in the overlap region (including nasal flow resistance), or pressure drop through the entire pharynx, were not significant. In a subgroup of subjects with more than 10% improvement in AHI, correlations between flow variables and AHI decrease were stronger than in all subjects.

CONCLUSIONS

The correlation between change in dPTAmax and improved AHI suggests that dPTAmax may be a useful index for internal airway loading due to anatomical narrowing, and may be better correlated with AHI than direct airway anatomic measurements.

Predictors of obstructive sleep apnea severity in adenotonsillectomy candidates

STUDY OBJECTIVES

There is uncertainty over which characteristics increase obstructive sleep apnea syndrome (OSAS) severity in children. In candidates for adenotonsillectomy (AT), we evaluated the relationship of OSAS severity and age, sex, race, body mass index (BMI), environmental tobacco smoke (ETS), prematurity, socioeconomic variables, and comorbidities.

DESIGN

Cross-sectional screening and baseline data were analyzed from the Childhood Adenotonsillectomy Trial, a randomized, controlled, multicenter study evaluating AT versus medical management. Regression analysis assessed the relationship between the apnea hypopnea index (AHI) and risk factors obtained by direct measurement or questionnaire.

SETTING

Clinical referral setting.

PARTICIPANTS

Children, ages 5 to 9.9 y with OSAS.

MEASUREMENTS AND RESULTS

Of the 1,244 children undergoing screening polysomnography, 464 (37%) were eligible (2 ≤ AHI < 30 or 1 ≤ obstructive apnea index [OAI] < 20 and without severe oxygen desaturation) and randomized; 129 (10%) were eligible but were not randomized; 608 (49%) had AHI/OAI levels below entry criteria; and 43 (3%) had levels of OSAS that exceeded entry criteria. Among the randomized children, univariate analyses showed significant associations of AHI with race, BMI z score, environmental tobacco smoke (ETS), family income, and referral source, but not with other variables. After adjusting for potential confounders, African American race (P = 0.003) and ETS (P = 0.026) were each associated with an approximately 20% increase in AHI. After adjusting for these factors, obesity and other factors were not significant.

CONCLUSIONS

Apnea hypopnea index level was significantly associated with race and environmental tobacco smoke, highlighting the potential effect of environmental factors, and possibly genetic factors, on pediatric obstructive sleep apnea syndrome severity. Efforts to reduce environmental tobacco smoke exposure may help reduce obstructive sleep apnea syndrome severity.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov (#NCT00560859).

Severe obstructive sleep apnea in a child with melanocortin-4 receptor deficiency

Obstructive sleep apnea (OSA) is a highly prevalent medical condition in obese children and is associated with significant neurocognitive, cardiovascular and metabolic derangements. Monogenic forms of obesity resulting from disruption of the leptin-melanocortin pathways have become more notable in recent years and distinguish between various obese phenotypes. However, the association of such disorders with OSA is not well established in children or adults. In this report, we describe a 23-month-old female with morbid obesity and OSA, who was found to carry a defect in the melanocortin-4 receptor (MC4R) pathway. This report emphasizes the genetic basis of obesity related to MC4R deficiency and OSA in children.

Computational fluid dynamics endpoints to characterize obstructive sleep apnea syndrome in children

Computational fluid dynamics (CFD) analysis may quantify the severity of anatomical airway restriction in obstructive sleep apnea syndrome (OSAS) better than anatomical measurements alone. However, optimal CFD model endpoints to characterize or assess OSAS have not been determined. To model upper airway fluid dynamics using CFD and investigate the strength of correlation between various CFD endpoints, anatomical endpoints, and OSAS severity, in obese children with OSAS and controls. CFD models derived from magnetic resonance images were solved at subject-specific peak tidal inspiratory flow; pressure at the choanae was set by nasal resistance. Model endpoints included airway wall minimum pressure (Pmin), flow resistance in the pharynx (Rpharynx), and pressure drop from choanae to a minimum cross section where tonsils and adenoids constrict the pharynx (dPTAmax). Significance of endpoints was analyzed using paired comparisons (t-test or Wilcoxon signed rank test) and Spearman correlation. Fifteen subject pairs were analyzed. Rpharynx and dPTAmax were higher in OSAS than control and most significantly correlated to obstructive apnea-hypopnea index (oAHI), r = 0.48 and r = 0.49, respectively (P < 0.01). Airway minimum cross-sectional correlation to oAHI was weaker (r = -0.39); Pmin was not significantly correlated. CFD model endpoints based on pressure drops in the pharynx were more closely associated with the presence and severity of OSAS than pressures including nasal resistance, or anatomical endpoints. This study supports the usefulness of CFD to characterize anatomical restriction of the pharynx and as an additional tool to evaluate subjects with OSAS.