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.

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.

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.

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.

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.

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.

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.

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.

Adenotonsillectomy in obese children with obstructive sleep apnea syndrome: magnetic resonance imaging findings and considerations.

OBJECTIVE: The reasons why adenotonsillectomy (AT) is less effective treating obese children with obstructive sleep apnea syndrome (OSAS) are not understood. Thus, the aim of the study was to evaluate how anatomical factors contributing to airway obstruction are affected by AT in these children. METHODS: Twenty-seven obese children with OSAS (age 13.0 ± 2.3 y, body mass index Z-score 2.5 ± 0.3) underwent polysomnography and magnetic resonance imaging of the head during wakefulness before and after AT. Volumetric analysis of the upper airway and surrounding tissues was performed using commercial software (AMIRA®). RESULTS: Patients were followed for 6.1 ± 3.6 mo after AT. AT improved mean obstructive apnea-hypopnea index (AHI) from 23.7 ± 21.4 to 5.6 ± 8.7 (P < 0.001). Resolution of OSAS was noted in 44% (12 of 27), but only in 22% (4 of 18) of those with severe OSAS (AHI > 10). AT increased the volume of the nasopharynx and oropharynx (2.9 ± 1.3 versus 4.4 ± 0.9 cm(3), P < 0.001, and 3.2 ± 1.2 versus 4.3 ± 2.0 cm(3), P < 0.01, respectively), reduced tonsils (11.3 ± 4.3 versus 1.3 ± 1.4 cm(3), P < 0.001), but had no effect on the adenoid, lingual tonsil, or retropharyngeal nodes. A small significant increase in the volume of the soft palate and tongue was also noted (7.3 ± 2.5 versus 8.0 ± 1.9 cm(3), P = 0.02, and 88.2 ± 18.3 versus 89.3 ± 24.4 cm(3), P = 0.005, respectively). CONCLUSIONS: This is the first report to quantify volumetric changes in the upper airway in obese children with OSAS after adenotonsillectomy showing significant residual adenoid tissue and an increase in the volume of the tongue and soft palate. These findings could explain the low success rate of AT reported in obese children with OSAS and are important considerations for clinicians treating these children.

Deep cervical lymph node hypertrophy: a new paradigm in the understanding of pediatric obstructive sleep apnea.

OBJECTIVES/HYPOTHESIS: To determine if adenotonsillar hypertrophy is an isolated factor in pediatric obstructive sleep apnea (OSA), or if it is part of larger spectrum of cervical lymphoid hypertrophy. STUDY DESIGN: Prospective case control study. METHODS: A total of 70 screened patients (mean age 7.47 years) underwent polysomnography to confirm OSA, and then underwent MRI of the upper airway. Seventy-six matched controls (mean age 8.00 years) who already had an MRI underwent polysomnography. Volumetric analysis of lymphoid tissue volumes was carried out. Chi-square analysis and Student's t test were used to compare demographic data and lymph node volumes between cohorts. Fisher's Exact test and Chi-square analysis were used to compare sleep data. RESULTS: Patients and controls demonstrated no significant difference in mean age (7.47 vs. 8.00 yrs), weight (44.87 vs. 38.71 kg), height (124.68 vs. 127.65 cm), or body-mass index (23.63 vs. 20.87 kg/m(2)). OSA patients demonstrated poorer sleep measures than controls (P < 0.05) in all polysomnography categories (sleep efficiency, apnea index, apnea-hypopnea index, baseline SpO2, SpO2 nadir, baseline ETCO2, peak ETCO2 , and arousal awakening index). Children with OSA had higher lymphoid tissue volumes than controls in the retropharyngeal region (3316 vs. 2403 mm(3), P < 0.001), upper jugular region (22202 vs. 16819 mm(3), P < 0.005), and adenotonsillar region (18994 vs. 12675 mm(3), P < 0.0001). CONCLUSIONS: Children with OSA have larger volumes of deep cervical lymph nodes and adenotonsillar tissue than controls. This finding suggests a new paradigm in the understanding of pediatric OSA, and has ramifications for future research and clinical care.

Sleep and cardiometabolic function in obese adolescent girls with polycystic ovary syndrome.

OBJECTIVE: To compare the polysomnography findings and cardiometabolic function among adolescent girls with polycystic ovary syndrome (PCOS) and matched female and male controls. METHOD: Retrospective chart review of electronic medical records of 28 girls with PCOS (age: 16.8±1.9 years, body mass index (BMI) Z-score 2.4±0.4), 28 control females (age: 17.1±1.8, BMI Z-score 2.4±0.3) and 28 control males (age: 16.6±1.6, BMI Z-score 2.5±0.5) in a tertiary care centre. RESULTS: The prevalence of obstructive sleep apnoea (OSA) was higher in girls with PCOS compared to control females (16/28 (57%) vs. 4/28(14.3%), p<0.01); however, it was comparable to that of the control males (16/28(57%) vs. 21/28(75%), p=0.4). Girls with PCOS had a significantly higher prevalence of insulin resistance compared to control females and control males (20/28 (71.4%) vs. 9/22 (41.0%) (p=0.04) vs. 8/23 (34.8%) (p=0.01). Among girls with PCOS, those with OSA had significantly higher proportions of metabolic syndrome (MetS) (9/16 (56.3%) vs. 1/12 (8.3%) p=0.03), higher insulin resistance (14/16 (87.5%) vs. 6/12 (50%), p=0.04), elevated daytime systolic blood pressure (128.4±12.8 vs. 115.6±11.4, p<0.01), lower high-density lipoprotein (HDL) (38.6±8.7 vs. 49±10.9, p=0.01) and elevated triglycerides (TG) (149.7±87.7 vs. 93.3±25.8, p=0.03) compared to those without OSA. CONCLUSIONS: We report a higher prevalence of OSA and metabolic dysfunction in a selected group of obese girls with PCOS referred with sleep-related complaints compared to BMI-matched control girls without PCOS. We also report higher prevalence of cardiometabolic dysfunction in girls with PCOS and OSA compared to girls with PCOS without OSA.

Upper airway lymphoid tissue size in children with sickle cell disease.

BACKGROUND: The prevalence of obstructive sleep apnea syndrome (OSAS) is higher in children with sickle cell disease (SCD) as compared with the general pediatric population. It has been speculated that overgrowth of the adenoid and tonsils is an important contributor. METHODS: The current study used MRI to evaluate such an association. We studied 36 subjects with SCD (aged 6.9 ± 4.3 years) and 36 control subjects (aged 6.6 ± 3.4 years). RESULTS: Compared with control subjects, children with SCD had a significantly smaller upper airway (2.8 ± 1.2 cm(3) vs 3.7 ± 1.6 cm(3), P < .01), and significantly larger adenoid (8.4 ± 4.1 cm(3) vs 6.0 ± 2.2 cm(3), P < .01), tonsils (7.0 ± 4.3 cm(3) vs 5.1 ± 1.9 cm(3), P < .01), retropharyngeal nodes (3.0 ± 1.9 cm(3) vs 2.2 ± 0.9 cm(3), P < .05), and deep cervical nodes (15.7 ± 5.7 cm(3) vs 12.7 ± 4.0 cm(3), P < .05). Polysomnography showed that 19.4% (seven of 36) of children with SCD had OSAS compared with 0% (zero of 20) of control subjects (P < .05) and that in children with SCD the apnea-hypopnea index correlated positively with upper airway lymphoid tissues size (r = 0.57, P < 001). In addition, children with SCD had lower arterial oxygen saturation nadir (84.3% ± 12.3% vs 91.2% ± 4.2%, P < .05), increased peak end-tidal CO(2) (53.4 ± 8.5 mm Hg vs 42.3 ± 5.3 mm Hg, P < .001), and increased arousals (13.7 ± 4.7 events/h vs 10.8 ± 3.8 events/h, P < .05). CONCLUSIONS: Children with SCD have reduced upper airway size due to overgrowth of the surrounding lymphoid tissues, which may explain their predisposition to OSAS.

Screening for sleep-disordered breathing and excessive daytime sleepiness in adolescent girls with polycystic ovarian syndrome.

OBJECTIVE: To determine the prevalence and clinical and metabolic correlates of sleep-disordered breathing (SDB) and excessive daytime sleepiness (EDS) in adolescent girls with polycystic ovarian syndrome (PCOS). STUDY DESIGN: Standardized questionnaires were administered to participants with PCOS and age-, sex-, ethnicity-, and body mass index (BMI) z score-matched controls. Medical records were reviewed for anthropometric and metabolic data. RESULTS: We studied 103 participants with PCOS (16.9 ± 1.5 years) and 90 controls (16.8 ± 1.7 years). Compared with controls, girls with PCOS had a higher prevalence of SDB (45.6% vs 27.8%; P = .01) and EDS (54.4% vs 35.6%; P < .01). Within PCOS, those with SDB had higher BMI z score (2.1 ± 0.5 vs 1.7 ± 0.6; P < .01), higher homeostatic model assessment index (5.1 ± 2.3 vs 4.1 ± 3.5; P < .01), and higher prevalence of the metabolic syndrome (MetS) (42.6% vs 16.1%; P = .003) compared with those without SDB. Similarly, participants with PCOS and EDS had a higher BMI z score (2.0 ± 0.6 vs 1.7 ± 0.6; P = .03), higher homeostatic model assessment index (5.1 ± 2.9 vs 3.8 ± 3.1; P = .01), and higher rate of MetS (39.3% vs. 14.9%; P < .01) compared with those without EDS. MetS was independently associated with SDB (OR, 3.2; 95% CI, 1.0-10.1) and EDS (OR, 4.5; 95% CI, 1.2-16). CONCLUSIONS: SDB and EDS are highly prevalent in adolescent girls with PCOS compared with matched controls. The MetS is independently associated with SDB and EDS in this group.

Upper airway structure and body fat composition in obese children with obstructive sleep apnea syndrome.

RATIONALE: Mechanisms leading to obstructive sleep apnea syndrome (OSAS) in obese children are not well understood. OBJECTIVES: The aim of the study was to determine anatomical risk factors associated with OSAS in obese children as compared with obese control subjects without OSAS. METHODS: Magnetic resonance imaging was used to determine the size of upper airway structure, and body fat composition. Paired analysis was used to compare between groups. Mixed effects regression models and conditional multiple logistic regression models were used to determine whether body mass index (BMI) Z-score was an effect modifier of each anatomic characteristic as it relates to OSAS. MEASUREMENTS AND MAIN RESULTS: We studied 22 obese subjects with OSAS (12.5 ± 2.8 yr; BMI Z-score, 2.4 ± 0.4) and 22 obese control subjects (12.3 ± 2.9 yr; BMI Z-score, 2.3 ± 0.3). As compared with control subjects, subjects with OSAS had a smaller oropharynx (P < 0.05) and larger adenoid (P < 0.01), tonsils (P < 0.05), and retropharyngeal nodes (P < 0.05). The size of lymphoid tissues correlated with severity of OSAS whereas BMI Z-score did not have a modifier effect on these tissues. Subjects with OSAS demonstrated increased size of parapharyngeal fat pads (P < 0.05) and abdominal visceral fat (P < 0.05). The size of these tissues did not correlate with severity of OSAS and BMI Z-score did not have a modifier effect on these tissues. CONCLUSIONS: Upper airway lymphoid hypertrophy is significant in obese children with OSAS. The lack of correlation of lymphoid tissue size with obesity suggests that this hypertrophy is caused by other mechanisms. Although the parapharyngeal fat pads and abdominal visceral fat are larger in obese children with OSAS we could not find a direct association with severity of OSAS or with obesity.

Changes in heart rate variability after adenotonsillectomy in children with obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular morbidity and mortality, and increased sympathetic activity is considered to be a causative link in this association. Higher levels of sympathetic activity have been reported in children with OSAS. Sympathetic predominance is indicated on heart rate variability (HRV) analysis by increased heart rate (HR) and a higher ratio of low-frequency to high-frequency band power (LF/HF). Improvement in OSAS after adenotonsillectomy (AT) in children with OSAS could, therefore, be associated with reduced HR and reduced LF/HF. METHODS: Changes in HR and time and frequency components of HRV were retrospectively analyzed in 2-min epochs free of respiratory events during light, deep, and rapid-eye-movement (REM) sleep in children with OSAS who underwent polysomnography before and after AT. RESULTS: Eighteen children with OSAS, aged 4.9 ± 2.4 years (mean ± SD) were studied. After AT, the apnea-hypopnea index decreased from 31.9 ± 24.8 events/h to 4.1 ± 3.7 events/h. The HR decreased after AT in all stages of sleep (99.8 ± 16.9 beats/min to 80.7 ± 12.9 beats/min [light sleep]; 100.2 ± 15.4 beats/min to 80.5 ± 12.4 beats/min [deep sleep)]; and 106.9 ± 16.4 beats/min to 87.0 ± 12.1 beats/min [REM sleep]), as did the LF/HF (1.6 ± 2.7 to 0.6 ± 0.5 [light sleep]; 1.2 ± 1.6 to 0.5 ± 0.6 [deep sleep]; and 3.0 ± 5.4 to 1.4 ± 1.7 [REM sleep]). CONCLUSIONS: The proportion of sympathetic activity of the autonomic nervous system declines in children with OSAS after AT in association with improvement in sleep-disordered breathing.

Rhino-sinus involvement in children with obstructive sleep apnea syndrome.

OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) is commonly associated with adenotonsillar hypertrophy. We hypothesized that respiratory perturbations extend to other regions of the upper respiratory tract in such children, particularly to rhino-sinus regions. STUDY DESIGN: A prospective case control study using Magnetic Resonance Imaging (MRI) of the upper airway and surrounding tissues of OSAS and controls. Magnetic resonance imaging was used to evaluate radiographic changes within the: paranasal sinuses, middle ear and mastoid air cells, and the nasal passages. RESULTS: We studied 54 OSAS (age 5.7 ± 3.0 years) and 54 controls (age 6.2 ± 2.0 years, P = NS). Children with OSAS had significantly more opacification of: maxillary sinuses (P < 0.05), sphenoid sinuses (P < 0.01), and mastoid air cells (P < 0.01). They also had significantly more: middle ear effusions, (P < 0.001), prominence of inferior nasal turbinate(s) (P < 0.05), and deviation of the nasal septum (P < 0.05). CONCLUSIONS: Childhood OSAS is associated with a wide range of upper respiratory tract perturbations and is not limited to adenoid and tonsillar hypertrophy.

Adenotonsillectomy outcomes in treatment of obstructive sleep apnea in children: a multicenter retrospective study.

RATIONALE: The overall efficacy of adenotonsillectomy (AT) in treatment of obstructive sleep apnea syndrome (OSAS) in children is unknown. Although success rates are likely lower than previously estimated, factors that promote incomplete resolution of OSAS after AT remain undefined. OBJECTIVES: To quantify the effect of demographic and clinical confounders known to impact the success of AT in treating OSAS. METHODS: A multicenter collaborative retrospective review of all nocturnal polysomnograms performed both preoperatively and postoperatively on otherwise healthy children undergoing AT for the diagnosis of OSAS was conducted at six pediatric sleep centers in the United States and two in Europe. Multivariate generalized linear modeling was used to assess contributions of specific demographic factors on the post-AT obstructive apnea-hypopnea index (AHI). MEASUREMENTS AND MAIN RESULTS: Data from 578 children (mean age, 6.9 +/- 3.8 yr) were analyzed, of which approximately 50% of included children were obese. AT resulted in a significant AHI reduction from 18.2 +/- 21.4 to 4.1 +/- 6.4/hour total sleep time (P < 0.001). Of the 578 children, only 157 (27.2%) had complete resolution of OSAS (i.e., post-AT AHI <1/h total sleep time). Age and body mass index z-score emerged as the two principal factors contributing to post-AT AHI (P < 0.001), with modest contributions by the presence of asthma and magnitude of pre-AT AHI (P < 0.05) among nonobese children. CONCLUSIONS: AT leads to significant improvements in indices of sleep-disordered breathing in children. However, residual disease is present in a large proportion of children after AT, particularly among older (>7 yr) or obese children. In addition, the presence of severe OSAS in nonobese children or of chronic asthma warrants post-AT nocturnal polysomnography, in view of the higher risk for residual OSAS.

Computational fluid dynamics modeling of the upper airway of children with obstructive sleep apnea syndrome in steady flow.

Computational fluid dynamic (CFD) analysis was used to model the effect of airway geometry on internal pressure in the upper airway of three children with obstructive sleep apnea syndrome (OSAS), and three controls. Model geometry was reconstructed from magnetic resonance images obtained during quiet tidal breathing, meshed with an unstructured grid, and solved at normative peak resting flow. The unsteady Reynolds-averaged Navier-Stokes equations were solved with steady flow boundary conditions in inspiration and expiration, using a two-equation low-Reynolds number turbulence model. Model results were validated using an in-vitro scale model, unsteady flow simulation, and reported nasal resistance measurements in children. Pharynx pressure drop strongly correlated to airway area restriction. Inspiratory pressure drop was primarily proportional to the square of flow, consistent with pressure losses due to convective acceleration caused by area restriction. On inspiration, in OSAS pressure drop occurred primarily between the choanae and the region where the adenoids overlap the tonsils (overlap region) due to airway narrowing, rather than in the nasal passages; in controls the majority of pressure drop was in the nasal passages. On expiration, in OSAS the majority of pressure drop occurred between the oropharynx (posterior to the tongue) and overlap region, and local minimum pressure in the overlap region was near atmospheric due to pressure recovery in the anterior nasopharynx. The results suggest that pharyngeal airway shape in children with OSAS significantly affects internal pressure distribution compared to nasal resistance. The model may also help explain regional dynamic airway narrowing during expiration.