The effect of posture on airflow distribution, airway geometry and air velocity in healthy subjects.

BACKGROUND: Gravity, and thus body position, can affect the regional distribution of lung ventilation and blood flow. Therefore, body positioning is a potential tool to improve regional ventilation, thereby possibly enhancing the effect of respiratory physiotherapy interventions. In this proof-of-concept study, functional respiratory imaging (FRI) was used to objectively assess effects of body position on regional airflow distribution in the lungs. METHODS: Five healthy volunteers were recruited. The participants were asked during FRI first to lie in supine position, afterwards in standardized right lateral position. RESULTS: In right lateral position there was significantly more regional ventilation also described as Imaging Airflow Distribution in the right lung than in the left lung (P < 0.001). Air velocity was significantly higher in the left lung (P < 0.05). In right lateral position there was significantly more airflow distribution in the right lung than in the left lung (P < 0.001). Significant changes were observed in airway geometry resulting in a decrease in imaged airway volume (P = 0.024) and a higher imaged airway resistance (P = 0.029) in the dependent lung. In general, the effect of right lateral position caused a significant increase in regional ventilation (P < 0.001) in the dependent lung when compared with the supine position. CONCLUSIONS: Changing body position leads to significant changes in regional lung ventilation, objectively assessed by FRI The volume based on the imaging parameters in the dependent lung is smaller in the lateral position than in the supine position. In right lateral decubitus position, airflow distribution is greater in dependent lung compared to the nondependent lung. TRIAL REGISTRATION: The trial has been submitted to www. CLINICALTRIALS: gov with identification number NCT01893697 on 07/02/2013.

Functional imaging improves patient selection for mandibular advancement device treatment outcome in sleep-disordered breathing: a prospective study.

STUDY OBJECTIVES: Mandibular advancement devices (MADs) are a noninvasive treatment option for patients with obstructive sleep apnea (OSA) and act by increasing the upper airway volume. However, the exact therapeutic mechanism of action remains unclear. The aim of this study was to assess MAD mechanisms using functional imaging that combines imaging techniques and computational fluid dynamics and assess associations with treatment outcome. METHODS: One hundred patients with OSA were prospectively included and treated with a custom-made MAD at a fixed 75% protrusion. A low-dose computed tomography scan was made with and without MADs for computational fluid dynamics analysis. Patients underwent a baseline and 3-month follow-up polysomnography to evaluate treatment efficacy. A reduction in apnea-hypopnea index ≥ 50% defined treatment response. RESULTS: Overall, 71 patients completed both 3-month follow-up polysomnography and low-dose computed tomography scan with computational fluid dynamics analysis. MAD treatment significantly reduced the apnea-hypopnea index (16.5 [10.4-23.6] events/h to 9.1 [3.9-16.4] events/h; P < .001, median [quartile 1-quartile 3]) and significantly increased the total upper airway volume (8.6 [5.4-12.8] cm3 vs 10.7 [6.4-15.4] cm3; P = .003), especially the velopharyngeal volume (2.1 [0.5-4.1] cm3 vs 3.3 [1.8-6.0] cm3; P < .001). However, subanalyses in responders and nonresponders only showed a significant increase in the total upper airway volume in responders, not in nonresponders. CONCLUSIONS: MAD acts by increasing the total upper airway volume, predominantly due to an increase in the velopharyngeal volume. Responders showed a significant increase in the total upper airway volume with MAD treatment, while there was no significant increase in nonresponders. Findings add evidence to implement functional imaging using computational fluid dynamics in routine MAD outcome prediction. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Predicting Therapeutic Outcome of Mandibular Advancement Device Treatment in Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT01532050; Identifier: NCT01532050. CITATION: Van Gaver H, Op de Beeck S, Dieltjens M, et al. Functional imaging improves patient selection for mandibular advancement device treatment outcome in sleep-disordered breathing: a prospective study. J Clin Sleep Med. 2022;18(3):739-750.

Phenotypic Labelling Using Drug-Induced Sleep Endoscopy Improves Patient Selection for Mandibular Advancement Device Outcome: A Prospective Study.

STUDY OBJECTIVES: Mandibular advancement device (MAD) outcome varies between patients. We hypothesized that upper airway collapse sites, patterns, and degrees assessed during baseline drug-induced sleep endoscopy (DISE) affect MAD outcome. METHODS: One hundred patients with obstructive sleep apnea (OSA) were included and underwent baseline type 1 polysomnography. MAD was fitted intraorally at fixed 75% maximal protrusion. A total of 72 patients completed 3-month follow-up polysomnography and baseline DISE. Response was defined as apnea-hypopnea index (AHI) reduction ≥ 50%, deterioration as AHI increases during MAD treatment compared to baseline. RESULTS: Adjusting for baseline AHI and body mass index, patients with tongue base collapse showed 3.69 higher odds (1.27-10.73; P = .0128) for response. Complete concentric collapse at the level of the palate (5.32 [1.21-23.28]; P = .0234) and complete laterolateral oropharyngeal collapse (6.62 [1.14-38.34]; P = .0330) related to deterioration. Results for tongue base collapse and complete concentric collapse at the level of the palate were confirmed in the moderate to severe OSA subgroup. Applying these results to this selected subgroup increased response rate with 54% and decreased deterioration rate with 53%. These results were confirmed using other response and deterioration definitions. CONCLUSIONS: Three baseline DISE phenotypes identified during drug-induced sleep were significantly related to MAD treatment outcome: one beneficial, tongue base collapse, and two adverse, complete concentric collapse at the level of the palate and complete laterolateral oropharyngeal collapse. If confirmed in future prospective studies, these results could guide patient selection for MAD outcome. CLINICAL TRIAL REGISTRATION: This prospective clinical trial (PROMAD) was registered on Clinicaltrials.gov with identifier: NCT01532050. CITATION: Op de Beeck S, Dieltjens M, Verbruggen AE, Vroegop AV, Wouters K, Hamans E, Willemen M, Verbraecken J, De Backer WA, Van de Heyning PH, Braem MJ, Vanderveken OM. Phenotypic labelling using drug-induced sleep endoscopy improves patient selection for mandibular advancement device outcome: a prospective study. J Clin Sleep Med. 2019;15(8):1089-1099.

Evaluation of a Trial Period With a Sleep Position Trainer in Patients With Positional Sleep Apnea.

STUDY OBJECTIVES: To assess the overall clinical effectiveness of a sleep position trainer (SPT) in patients with positional obstructive sleep apnea (POSA) and to evaluate how many patients were willing to continue treatment after a 1-month trial period. METHODS: Patients in whom POSA was diagnosed underwent a 1-month trial period with the SPT. Home sleep apnea tests were used to measure baseline data and data following the trial period with the SPT. RESULTS: The 79 patients who completed the study protocol were 81% male, had a mean age of 52 ± 12 years, and a median baseline respiratory event index (REI) of 11 (8, 16) events/h. A significant reduction in overall REI to 5 (3, 10) events/h was observed with the SPT as compared to baseline (P < .001). The median percentage of sleep time in the supine position decreased significantly from 27 (20, 48) to 7 (2, 20) with the SPT (P < .001). Adherence was found to be 95 ± 8%. Of the 44 patients who decided to continue treatment, 27 were categorized as responders (having a decrease in REI of at least 50%) and 17 were non-responders. The most important reasons for not purchasing the SPT were poor objective results, intolerance to the vibrations, cost of the device, persistent daytime sleepiness, or patient preference for other treatment options. CONCLUSIONS: Treatment with the SPT came with high adherence rates and was effective in reducing REI and supine sleep position. The trial period is in the patients' best interest, as it may prevent those who will not benefit from positional training from purchasing an SPT.

Development of a Clinical Pathway and Technical Aspects of Upper Airway Stimulation Therapy for Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is a common disease with high morbidity and related mortality. Narrowing and collapse of the pharyngeal airway during sleep characterize the disease, resulting in a decrease (hypopnea) or a complete cessation (apnea) of oronasal airflow. Upper airway stimulation (UAS), using electrical neurostimulation of the hypoglossal nerve (n. XII) synchronized with ventilation, is a novel, evolving treatment option. UAS was found to be an effective treatment in CPAP-intolerant patients. The treatment success is partly due to the strict selection of the patients, based on previous findings. Furthermore, post-operative follow-up is needed in order to maintain or improve treatment outcome. Therefore, a clinical pathway, which provides structure and standardization, is crucial. In this paper, the aim is to discuss the technical aspects of UAS therapy and to describe a clinical pathway to organize the care process of UAS for OSA in a structured and standardized way.

Determinants of Objective Compliance During Oral Appliance Therapy in Patients With Sleep-Disordered Breathing: A Prospective Clinical Trial.

IMPORTANCE: The main reported reasons for discontinuation of oral appliance therapy for sleep-disordered breathing (SDB) are the presence of self-perceived adverse effects and self-appreciated lack of efficacy. However, these conclusions rely only on subjective compliance data. OBJECTIVE: To determine which parameters are correlated with objectively measured data on compliance with oral appliance therapy. DESIGN, SETTING, AND PARTICIPANTS: For 51 outpatients with SDB, a prospective clinical trial using oral appliance therapy was conducted at Antwerp University Hospital from February 7, 2011, to October 8, 2013 (38 [75%] males; mean [SD] age, 49.3 [9.0] years; mean [SD] apnea-hypopnea index, 14.9 [9.3] events per hour of sleep; mean [SD] body mass index [calculated as weight in kilograms divided by height in meters squared], 26.3 [2.8]). Analysis was performed November 5, 2014. INTERVENTION: Oral appliance therapy with a custom-made, titratrable mandibular advancement device (OAm). MAIN OUTCOMES AND MEASURES: Possible correlations were assessed between objective compliance and patients' anthropometric characteristics, polysomnographic parameters, and answers to 3 subjective questionnaires (the visual analog scale for snoring, the Epworth Sleepiness Scale, and an adverse effects questionnaire). RESULTS: Median oral appliance use was 6.4 hours per night (range, 4.7-7.2 hours per night) at the 3-month follow-up. None of the anthropometric and polysomnographic parameters were correlated with compliance. No correlation was found between objective compliance and reports of excessive daytime sleepiness. However, a significant inverse correlation was found between objective compliance and posttreatment visual analog scale values for snoring (P = .006; ρ = ­.40). In addition, objective compliance was correlated significantly with a more pronounced decrease in socially disturbing snoring (P = .005; ρ = 0.39). The presence of dry mouth was the only adverse effect that was negatively correlated with objective compliance at the 3-month follow-up (P < .05; ρ = ­.31). CONCLUSIONS AND RELEVANCE: Neither the anthropometric and polysomnographic parameters nor reports of excessive daytime sleepiness correlated with compliance during oral appliance therapy. The 2 parameters that were correlated with higher objective compliance during oral appliance therapy were a more pronounced decrease in snoring and the presence of dry mouth during treatment. TRIAL REGISTRATION: clinicaltrials.gov Identifiers: NCT01284881 and NCT01532050.

A promising concept of combination therapy for positional obstructive sleep apnea.

PURPOSE: The objective of this randomized controlled trial was to assess the additional effect of a chest-worn sleep position trainer (SPT) in patients with residual supine-dependent obstructive sleep apnea (sdOSA) under mandibular advancement device (MAD) therapy. METHODS: Baseline and follow-up polysomnography with MAD were performed. Twenty patients with sdOSA under MAD therapy underwent two consecutive randomized polysomnographies: one with SPT and one with combination of SPT + MAD. Data are presented as median (quartile 1, quartile 3). RESULTS: The SPT reduced the time spent in supine sleeping position compared to baseline and MAD therapy. Both MAD and SPT were individually effective in reducing the overall apnea/hypopnea index (AHI) significantly when compared to baseline from 20.8 (15.1; 33.6)/h at baseline to 11.0 (6.7; 13.8)/h and to 11.1 (3.5; 17.7)/h with MAD or SPT, respectively. The combination of SPT + MAD further reduced the overall AHI to 5.7 (3.6; 7.4), which was significantly lower than with MAD alone (p < 0.001) and SPT alone (p < 0.008), respectively. CONCLUSIONS: The results of this study indicate that combination of SPT + MAD leads to a higher therapeutic efficacy in patients with sdOSA under MAD therapy when compared to one of the treatment modalities alone.

Functional respiratory imaging as a tool to personalize respiratory treatment in patients with unilateral diaphragmatic paralysis.

A completely different treatment approach was chosen for 2 patients with unilateral diaphragmatic paralysis and complaints of dyspnea despite similar anatomic and physiologic abnormalities. These decisions were supported by results obtained by functional respiratory imaging (FRI). FRI generated functional information on lobar ventilation and local drug deposition. In the first patient, some lobes were poorly ventilated, and drug deposition simulation showed that some regions were undertreated. This patient underwent diaphragmatic plication to restore ventilation. In the second patient, all lobes were still ventilated. A conservative approach with regular follow-ups was chosen to wait for spontaneous recovery of the diaphragmatic function. Both patients improved subjectively and objectively. These cases demonstrate how novel medical imaging techniques such as FRI can be used to personalize respiratory treatment in patients with unilateral diaphragmatic paralysis.

Change in upper airway geometry between upright and supine position during tidal nasal breathing.

BACKGROUND: As the upper airway is the most important limiting factor for the deposition of inhalation medication in the lower airways, it is interesting to assess how its morphology varies between different postures. The goal of this study is to compare the upper airway morphology and functionality of healthy volunteers in the upright and supine positions during tidal nasal breathing and to search for baseline indicators for these changes. This is done by performing three-dimensional measurements on computed tomography (CT) and cone beam computed tomography (CBCT) scans. METHODS: This prospective study was approved by all relevant institutional review boards. All patients gave their signed informed consent. In this study, 20 healthy volunteers (mean age, 62 years; age range, 37-78 years; mean body mass index, 29.26; body mass index range, 21.63-42.17; 16 men, 4 women) underwent a supine low-dose CT scan and an upright CBCT scan of the upper airway. The (local) average (Savg) and minimal (Smin) cross-sectional area, the position of the latter, the concavity, and the airway resistance were examined to determine if they changed from the upright to the supine position. If changes were found, baseline parameters were sought that were indicators for these differences. RESULTS: There were five dropouts due to movement artifacts in the CBCT scans. Savg and Smin were 9.76% and 26.90% larger, respectively, in the CBCT scan than in the CT scan, whereas the resistance decreased by 26.15% in the upright position. The Savg of the region between the hard palate and the bottom of the uvula increased the most (49.85%). In people with a high body mass index, this value changed the least. The airway resistance in men decreased more than in women. CONCLUSIONS: This study demonstrated that there are differences in upper airway morphology and functionality between the supine and upright positions and that there are baseline indicators for these differences.

Objectively measured vs self-reported compliance during oral appliance therapy for sleep-disordered breathing.

BACKGROUND: Assessment of the overall therapeutic effectiveness of oral appliance therapy can only be realized through objectively measured compliance. The aims of this study were to assess objectively measured compliance during oral appliance therapy at 1-year follow-up and to compare these data with self-reported use. METHODS: Fifty-one eligible patients were enrolled in this 1-year prospective clinical study (men, 61%; mean age, 49 ± 10 years; apnea-hypopnea index, 18.0 ± 11.9 events/h sleep; BMI, 26.6 ± 4.1 kg/m²). Objective compliance during oral appliance therapy at 1-year follow-up was assessed with a microsensor thermometer. Subjective compliance was assessed by self-report. Patients with a mean objectively measured use of ≥ 4 h/night on 70% of nights monitored were considered regular users. The mean disease alleviation was calculated as a measure of overall therapeutic effectiveness. RESULTS: High agreement between objective and subjective compliance data at 1-year follow-up was reported (intraclass correlation coefficient, 0.8; 95% CI, 0.5-0.9), showing a mean subjective overestimation of 30 min (95% CI, -3.1 to 1.9; P = .02). The discontinuation rate at 1-year follow-up was 9.8%. The objective mean use rate was 6.4 ± 1.7 h/night at 1-year follow-up in continuing users, with a regular use rate of 83%. The mean disease alleviation was 54.9%. CONCLUSIONS: This study is the first to our knowledge to report the 1-year results of objectively measured compliance during oral appliance therapy. In addition, a high agreement between objective and subjective compliance data were reported, with a mean subjective overestimation of 30 min. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01284881; URL: www.clinicaltrials.gov.

Objective measurement of compliance during oral appliance therapy for sleep-disordered breathing.

BACKGROUND: Oral appliance (OA) therapy is increasingly prescribed as a non-continuous positive airway pressure treatment modality for sleep-disordered breathing (SDB). Although OA therapy is reported to be efficacious for the treatment of SDB, data on compliance remain limited to self-report. METHODS: In this 3-month prospective clinical trial, the main outcome was to assess the safety and feasibility of an objective measurement of compliance during OA therapy using an embedded microsensor thermometer with on-chip integrated readout electronics in 51 consecutive patients with an established diagnosis of SDB (AHI 18.0 ± 11.9/h; age 47 ± 10 y; BMI 26.6 ± 4.0 kg/m(2); men/women: 31/20). Patients were unaware of the purpose of the study. RESULTS: No microsensor-related adverse events were recorded. In addition, no problems were encountered during the readout of the compliance data. Out of 51 microsensors, one had a technical defect and was lost to follow-up. In this study, the overall objective mean rate of OA use was 6.6 ± 1.3 h per day with a regular OA users' rate of 82% at the 3-month follow-up. Statistical analysis revealed no significant differences between objective and self-reported OA compliance data in this study. Measurement of the objective OA compliance allowed us to calculate the mean disease alleviation (MDA) as the product of objective compliance and therapeutic efficacy. MDA serves as a measure of the overall therapeutic effectiveness, and turned out to be 51.1%. CONCLUSIONS: The results illustrate the safety and feasibility of objective measurement of OA compliance. The objective measurement of OA compliance allows for calculation of the MDA.

Implanted upper airway stimulation device for obstructive sleep apnea.

OBJECTIVES/HYPOTHESIS: Previous feasibility studies have shown that electrical stimulation of the hypoglossal nerve can improve obstructive sleep apnea (OSA). The current study examined the safety and preliminary effectiveness of a second generation device, the Upper Airway Stimulation (UAS) system, and identified baseline predictors for therapy success. STUDY DESIGN: Two consecutive open prospective studies. METHODS: UAS systems were implanted in patients with moderate to severe OSA who failed or were intolerant of continuous positive airway pressure (CPAP). The study was conducted in 2 parts. In part 1, patients were enrolled with broad selection criteria. Apnea hypopnea index (AHI) was collected using laboratory-based polysomnography at preimplant and postimplant visits. Epworth Sleepiness Scale (ESS) and Functional Outcomes of Sleep Questionnaire (FOSQ) were also collected. In part 2, patients were enrolled using selection criteria derived from the experience in part 1. RESULTS: In part 1, 20 of 22 enrolled patients (two exited the study) were examined for factors predictive of therapy response. Responders had both a body mass index ≤32 and AHI ≤50 (P < .05) and did not have complete concentric palatal collapse. Part 2 patients (n = 8) were selected using responder criteria and showed an improvement on AHI from baseline, from 38.9 ± 9.8 to 10.0 ± 11.0 (P < .01) at 6 months postimplant. Both ESS and FOSQ improved significantly in part 1 and 2 subjects. CONCLUSIONS: The current study has demonstrated that therapy with upper airway stimulation is safe and efficacious in a select group of patients with moderate to severe OSA who cannot or will not use CPAP as primary treatment.

Weight loss and sleep-disordered breathing in childhood obesity: effects on inflammation and uric acid.

Sleep-disordered breathing (SDB) is prevalent in childhood obesity. It may be an independent risk factor for the metabolic syndrome. Possible mechanisms are inflammation and oxidative stress. Adenotonsillectomy in childhood obesity is associated with a high recurrence rate and risk of postoperative weight gain. Therefore, this study assessed the effects of SDB on inflammation and oxidative stress in childhood obesity before and after weight loss. We included 132 obese subjects between 10 and 18 years consecutively. Median age was 15.4 years (10.1-18.0). Mean BMI z-score was 2.72 ± 0.42. Leukocytes and differentiation, high sensitivity C-reactive protein (hs-CRP), and uric acid (UA) were determined at baseline and subjects underwent a sleep assessment. SDB was diagnosed in 39%. Linear regression analysis showed an association between UA(log) and oxygen desaturation index(log) (ODI(log)) (r = 0.20; P = 0.03), between leukocytes(log) and respiratory disturbance index(log) (RDI(log)) (r = 0.23; P = 0.01), and between lymphocytes(log) and RDI(log) (r = 0.19; P = 0.04). Follow-up was organized after 4-6 months of treatment. Median decrease in BMI z-score was 32%. Laboratory measurements were repeated. Subjects with SDB at baseline underwent a second sleep study. Of these 49 subjects, 12 showed residual SDB. This corresponds with a treatment success rate of 71%. Unlike changes in inflammatory markers, improvements in UA were associated with improvements in RDI and ODI (respectively: r = 0.44; P = 0.007, r = 0.41; P = 0.01). In conclusion, weight loss is effective in treating obese children with SDB. At baseline, a link exists between inflammation and SDB. Oxidative stress is reflected by UA at baseline and the concentration decreases after treatment according to improvements in SDB.

Electrical stimulation of the hypoglossal nerve in the treatment of obstructive sleep apnea.

Upper airway occlusion in obstructive sleep apnea has been attributed to a decline in pharyngeal neuromuscular activity occurring in a structurally narrowed airway. Surgical treatment focuses on the correction of anatomic abnormalities, but there is a potential role for activation of the upper airway musculature, especially with stimulation of the hypoglossal nerve and genioglossus muscle. We present evidence from research on upper airway neuromuscular electrical stimulation in animals and humans. We also present results from eight obstructive sleep apnea patients with a fully implanted system for hypoglossal nerve stimulation, demonstrating an improvement in upper airway collapsibility and obstructive sleep apnea severity. Future research, including optimization of device features and stimulation parameters as well as patient selection, is necessary to make hypoglossal nerve stimulation a viable alternative to positive airway pressure therapy and upper airway surgical procedures.

Correlation between the severity of sleep apnea and upper airway morphology in pediatric and adult patients.

PURPOSE OF REVIEW: Recent advances in upper airway imaging allow a better analysis of the upper airway morphology. With the increased accuracy of computed tomography, MRI and other imaging techniques, it becomes possible to identify very local changes in bony structure, soft tissues and lumen of the pharyngeal airway. These advances are able to provide new insights into obstructive sleep apnea (OSA) evaluation and treatment. RECENT FINDINGS: The present review intends to capture the current status of the research on the correlation between OSA severity and upper airway morphology. Morphological abnormalities that are responsible for OSA differ with age. Therefore, correlations between morphology and OSA in children and adults and the effects of puberty are discussed in different chapters. Literature provides several anatomical correlates that correlate with the severity of OSA but are not able to differentiate healthy individuals from OSA patients. SUMMARY: As anatomical correlates are not able to identify OSA in an individual, their main importance might lie in the selection of the ideal treatment on a patient-specific basis. Several sources report promising results in this use of morphological biomarkers. These, in combination with the new insights gained by the advances in imaging, should be the bases for additional research in the domain of treatment selection and result prediction.

Upper airway mechanics.

This review discusses the pathophysiological aspects of sleep-disordered breathing, with focus on upper airway mechanics in obstructive and central sleep apnoea, Cheyne-Stokes respiration and obesity hypoventilation syndrome. These disorders constitute the end points of a spectrum with distinct yet interrelated mechanisms that lead to substantial pathology, i.e. increased upper airway collapsibility, control of breathing instability, increased work of breathing, disturbed ventilatory system mechanics and neurohormonal changes. Concepts are changing. Although sleep apnoea is considered more and more to be an increased loop gain disorder, the central type of apnoea is now considered as an obstructive event, because it causes pharyngeal narrowing, associated with prolonged expiration. Although a unifying concept for the pathogenesis is lacking, it seems that these patients are in a vicious circle. Knowledge of common patterns of sleep-disordered breathing may help to identify these patients and guide therapy.

Sleep-disordered breathing: a new risk factor of suspected fatty liver disease in overweight children and adolescents?

INTRODUCTION: The aim of this retrospective study was to investigate if sleep-disordered breathing (SDB) was an independent predictor of suspected fatty liver disease in a clinical sample of overweight children and adolescents. MATERIALS AND METHODS: Consecutive overweight and obese children attending a pediatric obesity clinic underwent polysomnography, fasting blood sample, and abdominal ultrasound. RESULTS AND DISCUSSION: The respiratory disturbance index, percentage of total sleep time with SO2 < 90%, and SaO2nadir were associated with higher alanine amino-transferases (ALT) independent of abdominal obesity. Multiple logistic regression selected waist circumference (odds ratio = 1.05; p = 0.05) and SaO2nadir (odds ratio = 0.87; p = 0.03) as predictors of suggestive fatty liver disease, defined as ALT > 40 U/L and/or hyperechoic liver on abdominal ultrasound. This study supports the association between the severity of SDB and suspected fatty liver disease in a clinical sample of overweight children and adolescents. We recommend more research on the influence of SDB on the development of fatty liver disease and on the effect of treating sleep apnea on liver function parameters.

Sleep-disordered breathing, obesity, and airway inflammation in children and adolescents.

BACKGROUND: To investigate the relationship between obstructive sleep apnea syndrome (OSAS) and exhaled nitric oxide (eNO) in overweight children and adolescents without asthma or atopy and to assess whether obesity per se is associated with increased airway inflammation. METHODS: Consecutive overweight subjects without symptoms of asthma or allergy were recruited at a pediatric obesity clinic. A normal-weight control group without OSAS and asthma or allergy was also recruited. All subjects underwent polysomnography and two measurements of eNO (afternoon and morning after polysomnography). RESULTS: Controlling for age, the mean (+/- SD) afternoon eNO concentration was significantly higher in the snoring group (14.1 +/- 1.1 parts per billion [ppb]) compared with the normal-weight group (10.1 +/- 0.8 ppb; p = 0.03) and with the overweight group with normal polysomnography findings (8.9 +/- 0.8 ppb; p = 0.007). The afternoon eNO concentration was also different between the OSAS group (11.9 +/- 1.0 ppb) and the overweight group with normal polysomnography findings (p = 0.03). Morning eNO values were higher in the OSAS group (12.3 +/- 1.1 ppb) than in the normal weight group (9.9 +/- 0.8 ppb; p = 0.047) and in the overweight control group (9.7 +/- 0.7 ppb; p = 0.02). BMI z score was not significantly correlated with afternoon eNO concentration or with morning eNO concentration. CONCLUSION: This study illustrates that both habitual snoring and OSAS are associated with increased airway inflammation in overweight children as assessed by higher eNO levels. Furthermore, it was demonstrated that childhood obesity in the absence of sleep-disordered breathing is not associated with increased airway inflammation.

Comparison of a custom-made and a thermoplastic oral appliance for the treatment of mild sleep apnea.

RATIONALE: The efficacy of immediate adaptation of mandibular advancement devices made of thermoplastic material as a treatment option for sleep-disordered breathing (SDB) has been demonstrated in clinical studies. To date, there have been no studies comparing the efficacy of such prefabricated devices with custom-made devices. OBJECTIVES: Our purpose was to compare the efficacy of both types of devices in patients with SDB. METHODS: A randomized controlled cross-over trial, comprising 4 months of treatment with a thermoplastic and a custom-made device, with a 1-month washout interval. MEASUREMENTS AND MAIN RESULTS: A total of 35 patients (29 males; age, 49 +/- 9 yr; apnea-hypopnea index [AHI], 13 +/- 11 events/h; body mass index, 28 +/- 4 kg/m(2)) completed the protocol. AHI was only reduced with the custom-made device (P = 0.005). In addition, this device reduced snoring to a greater extent than the thermoplastic device. The success rate was higher with the custom-made device (60 vs. 31%; P = 0.02). One-third of the patients demonstrated compliance failure with the thermoplastic device, mainly because of insufficient overnight retention. Total failure rate with the thermoplastic device was 69%, whereas the majority (63%) of these were successfully treated with the custom-made device. At the end of the study, 82% of the patients preferred the custom-made device, and 9% had no preference (P < 0.0001). CONCLUSIONS: In this study, a custom-made device turned out to be more effective than a thermoplastic device in the treatment of SDB. Our results suggest that the thermoplastic device cannot be recommended as a therapeutic option nor can it be used as a screening tool to find good candidates for mandibular advancement therapy.