Risk Factors of Obstructive Sleep Apnea (OSA) in Pediatric Patients: A Systematic Review and Meta-analysis.

INTRODUCTION: This review aimed to assess the risk factors of Obstructive Sleep Apnea (OSA) in pediatric children, a common condition with serious long-term sequela. METHODS: PubMed, CENTRAL, Scopus, and Google Scholar were searched using the keywords "Apnea", "Obstructive Sleep" OR "Obstructive Sleep Apnea Syndrome" AND "Child" OR "Children" OR "Pediatrics". Data from 35 studies involving 497,688 pediatric patients diagnosed with OSA using polysomnography were reviewed. Risk factors examined included sex, obesity, neck circumference, tonsillar/adenoid hypertrophy, respiratory infections, nasal stenosis, parental OSA/smoking, ethnicity, preterm birth, and breastfeeding history. Relative Risk (RR) with 95% Confidence Intervals (95% CI) were calculated, using Cochrane Q and I² statistics to estimate heterogeneity. RESULTS: Tonsillar hypertrophy (RR = 3.55), adenoid hypertrophy (RR = 1.63), respiratory tract infection (RR = 2.59), obesity (RR = 1.74), and family history of OSA (RR = 3.03) were significantly associated with pediatric OSA. White ethnicity was protective (RR = 0.77). DISCUSSION: Recognizing these risk factors aids in early diagnosis and treatment of pediatric OSA.

A Relation between Obstructive Sleep Apnea in Pregnancy and Delivering Small for Gestational Age Infant-A Systematic Review.

Obstructive sleep apnea (OSA) during pregnancy can negatively affect both the mother and the baby. Our main goal is to show whether there is an association between OSA during pregnancy and delivering small for gestational age (SGA) infants. This systematic review was conducted according to the PRISMA 2020 statement using three databases: MEDLINE via PubMed, Scopus, and Cochrane Library. All databases were last accessed on 1 June 2023. The implemented systematic literature search identified 744 articles. After excluding reviews, meta-analyses, book chapters, case reports, and letters, 47 studies were analyzed, 18 of which finally met the inclusion criteria. The included studies mainly indicate that OSA during pregnancy may not significantly impact SGA, but some of them have shown the existence of this relation. Nevertheless, it is recommended that all pregnant women should be screened for symptoms of OSA and that sleep tests should be performed on those who show signs of it. Detecting and treating OSA early in pregnancy can help reduce the condition's negative effects. However, more extensive studies are still needed to gather clear evidence on the impact of an OSA diagnosis on mothers and babies.

Mechanical mechanism to induce inspiratory flow limitation in obstructive sleep apnea patients revealed from in-vitro studies.

Inspiratory flow limitation means that when the flowrate reaches a certain value, it no longer increases, or even decreases, which is called negative effort dependence flow limitation, even if the inspiration effort is increased. This occurs often in obstructive sleep apnea patients, but its mechanism remains unclear. To reveal the mechanism of inspiratory flow limitation, we constructed a unique partially collapsible in-vitro upper airway model of obstructive sleep apnea patients to observe the change of airway resistance with inspiratory driving pressure. The important findings demonstrate that with the increase of inspiratory effort, the driving pressure increases faster than the airway resistance in the early stages, and then the reverse occurs as the airway becomes narrower. The airway collapse caused by the transmural pressure can lead to a rapid increase in downstream resistance with the increase of inspiratory effort, which is the key reason causing the flow reduction and the formation of typical negative effort dependence flow limitation. The mechanical mechanism revealed in this study will lead to fully new insights into the study and treatment of obstructive sleep apnea.

Obstructive sleep apnoea and sleep disorders in pregnancy.

This review provides a summary for obstetricians, midwives, other health professionals and women contemplating pregnancy about the interactions between pregnancy and breathing during sleep. This review will first examine the normal physiological changes of pregnancy and their relationship to sleep-disordered breathing (SDB), and it will then summarise the current knowledge of SDB in pregnancy. Many changes in the respiratory system during pregnancy, particularly during the third trimester, can alter respiratory function during sleep, increasing the incidence and severity of SDB. These changes include increased ventilatory drive and metabolic rate, reduced functional residual capacity and residual volume, increased alveolar-arterial oxygen gradients and changes in the upper airway. The clinical importance of these changes during pregnancy is demonstrated by the increased incidence of snoring and obstructive sleep apnoea hypopnoea syndrome. As SDB is associated with obesity, the increasing incidence of obesity pre-pregnancy will likely increase SDB during pregnancy over the next decade. If a physician is asked to review a pregnant patient, they should always consider the possibility of SDB.

Effectiveness of functional orthodontic appliances in obstructive sleep apnea treatment in children: literature review / Eficácia dos aparelhos ortodônticos funcionais no tratamento da apneia obstrutiva do sono em crianças: revisão da literatura

Abstract Introduction: Obstructive sleep apnea syndrome is a common condition in childhood and if left untreated can result in many health problems. An accurate diagnosis of the etiology is crucial for obstructive sleep apnea treatment success. Functional orthodontic appliances that stimulate mandibular growth by forward mandibular positioning are an alternative therapeutic option in growing patients. Objective: To perform a literature review about the effects of functional orthodontic appliances used to correct the mandibular deficiency in obstructive sleep apnea treatment. Methods: The literature search was conducted in June 2020 using Cochrane Library; PubMed, EBSCO (Dentistry & Oral Sciences Source), LILACS Ovid; SciELO Web of Science; EMBASE Bireme and BBO Bireme electronic databases. The search included papers published in English, until June 2020, whose methodology referred to the types and effects of functional orthopedic appliances on obstructive sleep apnea treatment in children. Results: The search strategy identified thirteen articles; only four articles were randomized clinical studies. All studies using the oral appliances or functional orthopedic appliances for obstructive sleep apnea in children resulted in improvements in the apnea-hypopnea index score. The cephalometric (2D) and tomographic (3D) evaluations revealed enlargement of the upper airway and increase in the upper airspace, improving the respiratory function in the short term. Conclusion: Functional appliances may bean alternative treatment for obstructive sleep apnea, but it cannot be concluded that they are effective in treating pediatric obstructive sleep apnea. There are significant deficiencies in the existing evidence, mainly due to absence of control groups, small sample sizes, lack of randomization and no long-term results.

Resumo Introdução: A síndrome da apneia obstrutiva do sono é uma condição comum na infância e, se não tratada, pode resultar em muitos problemas de saúde. Um diagnóstico preciso da etiologia é crucial para o sucesso do tratamento dessa condição clínica. Aparelhos ortodônticos funcionais que estimulam o crescimento mandibular através do anteroposicionamento mandibular são uma opção terapêutica para pacientes em crescimento. Objetivo: Fazer uma revisão da literatura sobre os efeitos do aparelho ortodôntico funcional usado para corrigir a deficiência mandibular no tratamento da apneia obstrutiva do sono. Método: A pesquisa bibliográfica foi feita em junho de 2020 nos os bancos de dados eletrônicos da Cochrane Library; PubMed, EBSCO (Dentistry & Oral Sciences Source), Lilacs Ovid; SciELO Web of Science; Embase Bireme e BBO Bireme. A busca incluiu artigos publicados em inglês, até junho de 2020, cuja metodologia referia-se aos tipos e efeitos dos aparelhos ortopédicos funcionais no tratamento da apneia obstrutiva do sono em crianças. Resultados: A estratégia de busca identificou 19 artigos; apenas quatro eram estudos clínicos randomizados. Todos os estudos que usaram aparelhos orais ou aparelhos ortopédicos funcionais para apneia obstrutiva do sono em crianças resultaram em melhorias no índice de apneia-hipopneia. As avaliações cefalométrica (2D) e tomográfica (3D) mostraram alargamento das vias aéreas superiores e aumento do espaço das vias aéreas superiores, que melhoraram a função respiratória em curto prazo. Conclusão: Os aparelhos funcionais podem ser um tratamento opcional para apneia obstrutiva do sono, mas não é possível concluir que sejam eficazes na população pediátrica. Existem deficiências significativas nas evidências existentes, principalmente devido à ausência de grupos de controle, tamanho pequeno das amostras, falta de randomização e ausência de resultados em longo prazo.

Prevalence of upper airway resistance syndrome in the São Paulo Epidemiologic Sleep Study.

OBJECTIVE: To establish the prevalence of upper airway resistance syndrome (UARS) according to different diagnostic criteria and evaluate its epidemiological characteristics in a representative sample of a large urban center. METHODS: This was a single-center evaluation involving volunteers from EPISONO, an epidemiological study focused on sleep disturbances and related factors in adults from São Paulo, Brazil in 2007. RESULTS: Considering the diagnostic criteria for UARS to be an apnea-hypopnea index of <5 events/h, minimum SpO2 ≥ 92%, the presence of airflow limitation during sleep for ≥5% of total sleep time, and daytime symptoms (sleepiness and/or fatigue), we observed a prevalence of the condition of 3.1% (4.4% in women and 1.5% in men). CONCLUSIONS: Although the diagnostic criteria for UARS, or even its existence as a syndrome, are still a subject of debate in the literature, the findings from this epidemiological study highlights UARS as a non-hypoxic sleep-disordered breathing condition with a significant prevalence in the general population, being more frequent among female young adults.

Effectiveness of functional orthodontic appliances in obstructive sleep apnea treatment in children: literature review.

INTRODUCTION: Obstructive sleep apnea syndrome is a common condition in childhood and if left untreated can result in many health problems. An accurate diagnosis of the etiology is crucial for obstructive sleep apnea treatment success. Functional orthodontic appliances that stimulate mandibular growth by forward mandibular positioning are an alternative therapeutic option in growing patients. OBJECTIVE: To perform a literature review about the effects of functional orthodontic appliances used to correct the mandibular deficiency in obstructive sleep apnea treatment. METHODS: The literature search was conducted in June 2020 using Cochrane Library; PubMed, EBSCO (Dentistry & Oral Sciences Source), LILACS Ovid; SciELO Web of Science; EMBASE Bireme and BBO Bireme electronic databases. The search included papers published in English, until June 2020, whose methodology referred to the types and effects of functional orthopedic appliances on obstructive sleep apnea treatment in children. RESULTS: The search strategy identified thirteen articles; only four articles were randomized clinical studies. All studies using the oral appliances or functional orthopedic appliances for obstructive sleep apnea in children resulted in improvements in the apnea-hypopnea index score. The cephalometric (2D) and tomographic (3D) evaluations revealed enlargement of the upper airway and increase in the upper airspace, improving the respiratory function in the short term. CONCLUSION: Functional appliances may be an alternative treatment for obstructive sleep apnea, but it cannot be concluded that they are effective in treating pediatric obstructive sleep apnea. There are significant deficiencies in the existing evidence, mainly due to absence of control groups, small sample sizes, lack of randomization and no long-term results.

Endotyping Sleep Apnea One Breath at a Time: An Automated Approach for Separating Obstructive from Central Sleep-disordered Breathing.

Rationale: Determining whether an individual has obstructive or central sleep apnea is fundamental to selecting the appropriate treatment. Objectives: Here we derive an automated breath-by-breath probability of obstruction, as a surrogate of gold-standard upper airway resistance, using hallmarks of upper airway obstruction visible on clinical sleep studies. Methods: From five nocturnal polysomnography signals (airflow, thoracic and abdominal effort, oxygen saturation, and snore), nine features were extracted and weighted to derive the breath-by-breath probability of obstruction (Pobs). A development and initial test set of 29 subjects (development = 6, test = 23) (New York, NY) and a second test set of 39 subjects (Solingen, Germany), both with esophageal manometry, were used to develop Pobs and validate it against gold-standard upper airway resistance. A separate dataset of 114 subjects with 2 consecutive nocturnal polysomnographies (New York, NY) without esophageal manometry was used to assess the night-to-night variability of Pobs. Measurements and Main Results: A total of 1,962,229 breaths were analyzed. On a breath-by-breath level, Pobs was strongly correlated with normalized upper airway resistance in both test sets (set 1: cubic adjusted [adj.] R2 = 0.87, P < 0.001, area under the receiver operating characteristic curve = 0.74; set 2: cubic adj. R2 = 0.83, P < 0.001, area under the receiver operating characteristic curve = 0.7). On a subject level, median Pobs was associated with the median normalized upper airway resistance (set 1: linear adj. R2 = 0.59, P < 0.001; set 2: linear adj. R2 = 0.45, P < 0.001). Median Pobs exhibited low night-to-night variability [intraclass correlation(2, 1) = 0.93]. Conclusions: Using nearly 2 million breaths from 182 subjects, we show that breath-by-breath probability of obstruction can reliably predict the overall burden of obstructed breaths in individual subjects and can aid in determining the type of sleep apnea.

Frequency of flow limitation using airflow shape.

STUDY OBJECTIVES: The presence of flow limitation during sleep is associated with adverse health consequences independent of obstructive sleep apnea (OSA) severity (apnea-hypopnea index, AHI), but remains extremely challenging to quantify. Here we present a unique library and an accompanying automated method that we apply to investigate flow limitation during sleep. METHODS: A library of 117,871 breaths (N = 40 participants) were visually classified (certain flow limitation, possible flow limitation, normal) using airflow shape and physiological signals (ventilatory drive per intra-esophageal diaphragm EMG). An ordinal regression model was developed to quantify flow limitation certainty using flow-shape features (e.g. flattening, scooping); breath-by-breath agreement (Cohen's ƙ); and overnight flow limitation frequency (R2, %breaths in certain or possible categories during sleep) were compared against visual scoring. Subsequent application examined flow limitation frequency during arousals and stable breathing, and associations with ventilatory drive. RESULTS: The model (23 features) assessed flow limitation with good agreement (breath-by-breath ƙ = 0.572, p < 0.001) and minimal error (overnight flow limitation frequency R2 = 0.86, error = 7.2%). Flow limitation frequency was largely independent of AHI (R2 = 0.16) and varied widely within individuals with OSA (74[32-95]%breaths, mean[range], AHI > 15/h, N = 22). Flow limitation was unexpectedly frequent but variable during arousals (40[5-85]%breaths) and stable breathing (58[12-91]%breaths), and was associated with elevated ventilatory drive (R2 = 0.26-0.29; R2 < 0.01 AHI v. drive). CONCLUSIONS: Our method enables quantification of flow limitation frequency, a key aspect of obstructive sleep-disordered breathing that is independent of the AHI and often unavailable. Flow limitation frequency varies widely between individuals, is prevalent during arousals and stable breathing, and reveals elevated ventilatory drive. Clinical trial registration: The current observational physiology study does not qualify as a clinical trial.

The efficacy of surgery for upper airway resistance syndrome: A systematic review, meta-analysis and case series.

PURPOSE: Upper airway resistance syndrome (UARS) is a sleep related breathing disorder that was first described in 1993. This goal of this study is to determine the efficacy of surgical intervention for UARS. MATERIALS AND METHODS: Systematic review of the literature and a case series of UARS patients at a large integrated healthcare system. Meta-analysis was performed. RESULTS: For the systematic review, 971 abstracts were reviewed and 3 articles were included, yielding 49 subjects. All of the included studies were of level 3 or 4 evidence. Significant improvement in Epworth Sleepiness Scale (ESS) score was noted after surgery in two level 4 studies. No significant change in ESS was noted in one level 3 study. Our retrospective chart review of eleven UARS patients compared preoperative and postoperative ESS scores, as well as sleep study data. Patients underwent a variety of surgical procedures. Our findings show a significant improvement in mean ESS scores after surgery, from 11.0 (±3.5) to 7.0 (±4.8) with p = 0.01, though no difference in apnea hypopnea index (AHI) and respiratory disturbance index (RDI) were identified. Meta-analysis was performed on 2 studies from the systematic review and our cases series data. UARS surgery showed a mean change in ESS of -5.89 (95% CI, -8.29 to -3.50). CONCLUSIONS: This systematic review, meta-analysis and retrospective case series indicate that surgery may improve ESS scores in patients with UARS. AHI and RDI are unlikely to be impacted by surgery.

Altered K-complex morphology during sustained inspiratory airflow limitation is associated with next-day lapses in vigilance in obstructive sleep apnea.

STUDY OBJECTIVES: Determine if changes in K-complexes associated with sustained inspiratory airflow limitation (SIFL) during N2 sleep are associated with next-day vigilance and objective sleepiness. METHODS: Data from thirty subjects with moderate-to-severe obstructive sleep apnea who completed three in-lab polysomnograms: diagnostic, on therapeutic continuous positive airway pressure (CPAP), and on suboptimal CPAP (4 cmH2O below optimal titrated CPAP level) were analyzed. Four 20-min psychomotor vigilance tests (PVT) were performed after each PSG, every 2 h. Changes in the proportion of spontaneous K-complexes and spectral characteristics surrounding K-complexes were evaluated for K-complexes associated with both delta (∆SWAK), alpha (∆αK) frequencies. RESULTS: Suboptimal CPAP induced SIFL (14.7 (20.9) vs 2.9 (9.2); %total sleep time, p < 0.001) with a small increase in apnea-hypopnea index (AHI3A: 6.5 (7.7) vs 1.9 (2.3); p < 0.01) versus optimal CPAP. K-complex density (num./min of stage N2) was higher on suboptimal CPAP (0.97 ± 0.7 vs 0.65±0.5, #/min, mean ± SD, p < 0.01) above and beyond the effect of age, sex, AHI3A, and duration of SIFL. A decrease in ∆SWAK with suboptimal CPAP was associated with increased PVT lapses and explained 17% of additional variance in PVT lapses. Within-night during suboptimal CPAP K-complexes appeared to alternate between promoting sleep and as arousal surrogates. Electroencephalographic changes were not associated with objective sleepiness. CONCLUSIONS: Sustained inspiratory airflow limitation is associated with altered K-complex morphology including the increased occurrence of K-complexes with bursts of alpha as arousal surrogates. These findings suggest that sustained inspiratory flow limitation may be associated with nonvisible sleep fragmentation and contribute to increased lapses in vigilance.

Evaluation of the Oropharyngeal Airway Space in Class II Malocclusion Treated with Mandibular Activator: A Retrospective Study.

AIM: The development of a class II malocclusion is usually related to a reduced oropharyngeal airway space. In order to prevent airway obstruction, functional appliances are commonly used for orthodontic therapy. The aim of the article is to verify if these appliances could positively influence oropharyngeal diameters preventing the onset of future respiratory disorders. MATERIALS AND METHODS: A group of 10 patients treated at the Dental Clinic of San Gerardo Hospital in Monza with mandibular activator was selected. Ten similar untreated class II subjects with retrognathic mandible were used as control group. The cephalometric tracings were made on lateral teleradiographs of the skull before and after the active therapy with functional devices for the treated group and before and after growth peak for the control one. Descriptive statistical analysis was calculated for all the cephalometric values in both study cases and control group using Excel worksheet. The data distribution was evaluated with Shapiro-Wilk test and the in-between group discrepancies were evaluated with Mann-Whitney U test. RESULTS: At T1 period, both case and control groups showed a class II pattern. At T2 period, the study group shows an improvement in bones relationship with reduced ANB angles and OVJ measurements. The control group otherwise did not show any important changes in maxillo-mandibular discrepancies. The airway size increased in either group in most cases. No significant differences between the treated and control groups were detected for airway size neither in the upper, middle, nor lower level at the T1-T2 interval. CONCLUSION: The upper airway values did not show any significant discrepancies between the two groups during the observation period. CLINICAL SIGNIFICANCE: Functional devices were effective in solving class II relationships, but there is no evidence of successful breathing disorders prevention by using mandibular activators, probably due to the stability of airway tissues reached in pubertal age in both groups.

Novel method for evaluating the upper airway resistance using the ratio of neural respiratory drive to flow in OSA.

STUDY OBJECTIVES: Sleep is associated with a reduction in ventilation and an increase in upper airway resistance (UAR) in patients with obstructive sleep apnea (OSA). However, there is no consensus on the standard for assessment of UAR and therefore it is important to develop a method to reliably assess UAR in patients with OSA. The purpose of the present study is to determine whether the ratio of neural respiratory drive (NRD) to flow can be used to assess changes in UAR in OSA during sleep. METHODS: A total of 24 patients (21 men) with OSA and 10 normal subjects (6 males) were studied. The UAR was assessed by the ratio of NRD to flow, which measured by esophageal pressure (Poes), diaphragm electromyography (EMGdi) and superficial diaphragm electromyography (SEMGdi) in various stages including wakefulness, N2 sleep, N2 sleep with snoring, hypopneas, the in the "preapnea" states in OSA versus wakefulness, sleeponset, N2 sleep, N3 sleep in normal subjects. All subjects underwent overnight full polysomnography using standard techniques. RESULTS: Our study indicate that UAR was progressively higher from wakefulness to N2 sleep, N2 sleep with snoring, hypopneas, and the in the "preapnea" states in patients with OSA and had obvious difference in statistical significance (p < 0.05). We found NRD in hypopneas was lower than that in N2-snoring while the UAR in hypopneas was higher than that in N2-snoring.The UAR and NRD increased consecutively from wakefulness to N2 sleep and N3 sleep in normal subjects while the ventilation was reduced consecutively in NREM sleep. CONCLUSIONS: It is feasible to use the ratio of neural respiratory drive to flow to assess UAR in patients with OSA during sleep.

Partial epiglottectomy improves residual apnea-hypopnea index in patients with epiglottis collapse.

Continuous positive airway pressure treatment aggravates airway obstruction in patients with epiglottis collapse. In these patients, partial epiglottectomy can resolve epiglottis collapse by partial excision of the obstructed epiglottis. However, patients with epiglottic collapse usually have simultaneous obstructions on multiple levels, such as the soft palate, base of the tongue, etc. Therefore, sleep apnea cannot be controlled merely by resolving epiglottis collapse. The use of additional continuous positive airway pressure treatment after partial epiglottectomy is considered essential. However, no studies have yet evaluated the effect of partial epiglottectomy on continuous positive airway pressure treatment. In this study, we report on 2 patients with obstructive sleep apnea who underwent partial epiglottectomy. These 2 patients used autotitrating positive airway pressure treatment pre- and postoperatively. The present case report will provide insight into the effects of partial epiglottectomy on the use of positive-pressure devices.

Long term oral appliance therapy decreases stress symptoms in patients with upper airway resistance syndrome.

STUDY OBJECTIVES: To evaluate the long-term effects of a mandibular advancement device (MAD) on stress symptoms and cognitive function in patients with upper airway resistance syndrome (UARS) compared with placebo. METHODS: This study was a randomized placebo-controlled clinical trial. Thirty UARS patients were randomized into 2 groups: placebo and MAD groups. UARS criteria were the presence of sleepiness (Epworth Sleepiness Scale ≥ 10) and/or fatigue (Modified Fatigue Impact Scale ≥ 38) associated with an apnea-hypopnea index ≤ 5 events/h and a respiratory disturbance index > 5 events/h of sleep, and/or flow limitation in more than 30% of total sleep time. All patients completed the Rey Auditory-Verbal Learning Test, the Logical Memory test, the Stroop Color Test, the Trail Making Test, the Digit Symbol Substitution Test, and Inventory of Stress Symptoms. Cognition protocol was defined based on the most used neuropsychological tests in the literature. Evaluations were performed before and after 1.5 years of treatment. RESULTS: Mean adherence to placebo and to MAD was 6.6 ± 2.6 and 6.1 ± 2.4 h/night, respectively. Side effects reported by MAD group were minor and short-term. There was no statistically significant difference in Rey Auditory-Verbal Learning Test, Logical Memory test, Stroop Color Test, Trail Making Test, and Digit Symbol Substitution Test before and after 1.5 years of treatment in both groups. Inventory of Stress Symptoms score decreased at the alert phase and the resistance phase after 1.5 years of MAD treatment compared to the placebo. CONCLUSIONS: Mandibular advancement devices were effective in decreasing stress symptoms in UARS patients after 1.5 years of treatment. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Efficacy of Oral Appliance for Upper Airway Resistance Syndrome; URL: https://clinicaltrials.gov/ct2/show/record/NCT02636621; Identifier: NTC02636621.

Low-Quality Evidence Supports the Use of Mandibular Advancement Appliances in Managing Obstructive Sleep Apnea in Children.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Mandibular advancement appliances for the treatment of obstructive sleep apnea in children: a systematic review and meta-analysis. Yanyan M, Min Y, Xuemei G. Sleep Med 2019;60:145-51. SOURCE OF FUNDING: Funding support was granted by the National Natural Science Foundation of China and from the Seeding Grant for Medicine and Engineering Science of Peking University. TYPE OF STUDY/DESIGN: Systematic review and meta-analysis.

Observational Study of Pulse Transit Time in Children With Sleep Disordered Breathing.

Background: Pulse transit time (PTT) is a non-invasive measure of arousals and respiratory effort for which we aim to identify threshold values that detect sleep disordered breathing (SDB) in children. We also compare the sensitivity and specificity of oximetry with the findings of a multi-channel study. Methods: We performed a cross-sectional observational study of 521 children with SDB admitted for multi-channel sleep studies (pulse oximetry, ECG, video, sound, movement, PTT) in a secondary care centre. PTT data was available in 368 children. Studies were categorised as normal; primary snoring; upper airway resistance syndrome (UARS); obstructive sleep apnoea (OSA), and "abnormal other." Receiver operator characteristic curves were constructed for different PTT (Respiratory swing; Arousal index) thresholds using a random sample of 50% of children studied (training set); calculated thresholds of interest were validated against the other 50% (test set). Study findings were compared with oximetry categories (normal, inconclusive, abnormal) using data (mean and minimum oxygen saturations; oxygen desaturations > 4%) obtained during the study. Results: Respiratory swing of 17.92 ms identified SDB (OSA/UARS) with sensitivity: 0.80 (C.I. 0.62-0.90) and specificity 0.79 (C.I. 0.49-0.87). PTT arousal index of 16.06/ hour identified SDB (OSA/UARS) with sensitivity: 0.85 (95% C.I. 0.67-0.92) and specificity 0.37 (95% C.I. 0.17-0.48). Oximetry identified SDB (OSA) with sensitivity: 0.38 (C.I. 0.31-0.46) and specificity 0.98 (C.I. 0.97-1.00). Conclusions: PTT is more sensitive but less specific than oximetry at detecting SDB in children. The additional use of video and sound enabled detection of SDB in twice as many children as oximetry alone.

Upper airway morphological changes in obstructive sleep apnoea: effect of age on pharyngeal anatomy.

OBJECTIVE: To evaluate the upper airway morphology changes associated with ageing in adult Chinese patients with obstructive sleep apnoea. METHODS: A total of 124 male patients diagnosed with obstructive sleep apnoea by overnight polysomnography, who underwent upper airway computed tomography, were enrolled. The linear dimensions, cross-sectional area and volume of the upper airway region and the surrounding bony frame were measured. The association between ageing and upper airway morphology was analysed. RESULTS: Soft palate length, minimum cross-sectional area of the retroglossal region, lateral dimensions at the minimum cross-sectional area of the retropalatal and retroglossal regions, nasopharyngeal volume, and average cross-sectional area of the nasopharyngeal region were found to significantly increase with ageing in all patients, while the upper airway shape flattened with ageing. The volume of the retropalatal region increased with ageing among the patients with a body mass index of less than 24 kg/m2. The volume of parapharyngeal fat pad increased with ageing among patients with a body mass index greater than 28 kg/m2. CONCLUSION: A number of dimensional, cross-sectional and volumetric parameters of the pharynx increased with age, indicating that non-anatomical factors may play a more important role in the pathogenesis of obstructive sleep apnoea in aged patients.

Measurement of upper airway resistances: A simple way to assess its collapsibility?

PURPOSE: The collapsibility of the upper airway is a key factor in the pathogenesis of obstructive sleep apnea (OSA). The exact measurement of this parameter, typically performed by obtaining the critical pressure (Pcrit), has not been introduced into clinical practice. The techniques that are used to measure the upper airway resistance could provide information on its the collapsibility of the airway. The aim of this study was to associate resistance in the upper airway with the presence of OSA. METHODS: Using a cross-sectional design with a control group, consecutive cases that were seen in the Chest Diseases Sleep Unit were recruited after undergoing nocturnal polysomnography. The upper airway collapsibility was determined based on the change in its resistance from the standing position to the supine position with a flow interruption (Rint) device by measuring the angle formed between the pressure/flow lines (PF angle) between the two positions. RESULTS: The PF angle was greater in the OSA group than in the controls: 7.5° (4) vs. 4° (2) (P < .001), with a positive correlation between the width of the angle and the apnea-hypopnea index (AHI) (r: 0.28, P = .03). Placing the threshold level at 10°, a sensitivity of 25% was obtained, along with a specificity of 96%, for the diagnosis of OSA. CONCLUSION: The measurement of resistance in the upper airway using flow interruption (Rint) can predict the presence of moderate and severe OSA with high specificity but low sensitivity.

A6 neurons simultaneously modulate active expiration and upper airway resistance in rats.

NEW FINDINGS: What is the central question of this study? Do A6 neurons modulate active expiratory and airway responses evoked by hypercapnia/acidosis? What is the main finding and its importance? Acute inhibition of A6 neurons reduced active expiratory, inspiratory and the associated oropharyngeal and laryngeal motor responses to hypercapnia/acidosis. A6 neurons provide excitatory synaptic drive contributing to the central generation of inspiratory and expiratory motor activity as well as the control of upper airway resistance. ABSTRACT: During rest, inspiration is an active phenomenon, whereas expiration is passive. Under conditions of high chemical drive, such as hypercapnia/acidosis, there is an increase in inspiratory activity, expiration becomes active and upper airway resistance is reduced. The locus coeruleus noradrenergic neurons (A6 neurons) are activated when exposed to elevated CO2 /[H+ ] levels and modulate respiratory brainstem neurons regulating ventilation. However, the role of A6 neurons in the control of upper airway resistance is not fully understood. We tested the hypothesis that A6 neurons contribute to the central generation of active inspiratory and expiratory responses and the associated changes in the motor nerves controlling upper airway resistance during hypercapnia/acidosis in rats. Using a perfused brainstem-spinal cord preparation, we inhibited A6 neurons using pharmacogenetics and evaluated the active expiratory (abdominal nerve), laryngeal (cervical vagus nerve), oropharyngeal (hypoglossal nerve) and inspiratory (phrenic nerve) motor nerve responses to hypercapnia/acidosis. Acute inhibition of A6 neurons did not produce significant changes in the respiratory pattern in normocapnia. However, the hypercapnia/acidosis-induced active expiratory response and the associated changes in the motor nerves responsible for control of oropharyngeal and laryngeal resistance, as well as the inspiratory response were all reduced after inhibition of A6 neurons. Our data demonstrate that A6 neurons exert an important excitatory synaptic drive to the central generation of both active inspiratory and expiratory activities and modulate the control of upper airway resistance during hypercapnia/acidosis.