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Obstructive sleep apnoea syndrome is characterized by an obstruction in the upper airway due to the pharyngeal collapse during sleep. Mandibular advancement devices have gained success and large popularity as a non-invasive treatment for OSAS. Nevertheless, the effects of mandibular advancement devices were poorly investigated in literature. To this aim the paper proposes a procedure to achieve a numerical simulation model useful to assess the stress/strain distribution on the temporomandibular joint and periodontal ligaments caused by the mandibular advancement. The findings suggest that the mandibular roto-translation induced by the MAD provoke high stress on the molars and premolar teeth.

Obstructive sleep apnea (OSA) is a common chronic disease characterized by repetitive pharyngeal collapse during sleep. OSA is associated with cardiovascular disease and increased mortality, among other issues. Continuous positive airway pressure (CPAP) is considered first line therapy for OSA, but is not always tolerated. Both non-surgical and surgical alternative management strategies are available for the CPAP intolerant patient. This article explores controversies surrounding airway evaluation, definition of successful treatment, and surgical management of the CPAP intolerant patient with moderate to severe OSA. Controversies specific to maxillomandibular advancement (MMA) are also discussed.

Purpose: Electrical stimulation of the whole hypoglossal nerve (HGp-ES) has been demonstrated to enlarge the pharynx and improve pharyngeal stability and patency to airflow in all animals studied, but not in humans. The present study was undertaken to better understand the effect of HGp-ES on the human pharynx. Methods: Eight patients with obstructive sleep apnea who had implanted stimulators with electrodes positioned proximally on the main truck of the hypoglossus were studied under propofol sedation. Pharyngoscopy and air flow measurements at multiple levels of continuous positive airway pressure (CPAP) were performed before and during Hgp-ES. Results: HGp-ES that activates both tongue protrusors and retractors narrowed the pharyngeal lumen at the site of collapse (velopharynx in all subjects) from 1.38 ± 0.79 to 0.75 ± 0.44 cm2, p < 0.05 (measured at mid-range of CPAP levels) and lowered airflow (from 8.88 ± 2.08 to 6.69 ± 3.51 l/min, p < 0.05). Changes in critical pressure (Pcrit) and velopharyngeal compliance were not significant, but oropharyngeal compliance decreased (from 0.43 ± 0.18 to 0.32 ± 0.13 cm2/cmH2O, p < 0.05). No correlation was found between the pattern of change in luminal shape (determined as the ratio of a–p vs. lateral diameter when lowering CPAP) or changes in cross-sectional area and airflow during Hgp-ES. Conclusions: Our findings indicate that human retractors dominate when stimulated together with the protrusors during HGp-ES. While co-activation of retractors may be beneficial, it should be limited. We speculate that exercises that augment protrusor force may improve the response to hypoglossal stimulation. The exclusion of patients with concentric pharyngeal obstruction should be re-evaluated.

Brachycephalic airway syndrome (BAS) is a common disease in certain "flat-faced" dog breeds. This syndrome includes stenotic nares, elongated and thickened soft palate, laryngeal collapse, and tracheal hypoplasia. Pharyngeal collapse is also commonly observed, but it is unclear if laryngopharynx motions are merely sequelae or actually contribute to BAS respiratory symptoms. Laryngopharynx motion was imaged using dynamic four-dimensional computed tomography (4D-CT) during spontaneous respiration in four dogs with different BAS types. Dynamic 4D-CT showed laryngopharynx motion in the following order during inspiration: pharyngeal collapse, contraction, and laryngospasm. We concluded that dynamic 4D-CT is a highly-detailed diagnostic approach for detecting laryngopharynx motion. Pharyngeal contraction during inspiration appears to contribute toward the worsening of clinical respiratory signs of BAS.

The aim of this retrospective study was to determine the frequency of pharyngeal collapse in a large group of brachycephalic dogs undergoing videofluoroscopic assessment of swallowing or airway diameter. We hypothesized that brachycephalic dogs would have pharyngeal collapse more frequently than dolichocephalic or mesocephalic dogs with or without airway collapse. The medical records database was searched for brachycephalic dogs undergoing videofluoroscopy of swallowing or airway diameter between January 1, 2006 and December 31, 2015. A cohort of dolichocephalic/mesocephalic dogs with videofluoroscopically confirmed airway collapse was age and time matched for comparison. A control group of dolichocephalic/mesocephalic dogs that did not have documented airway collapse was also evaluated. All fluoroscopic studies were assessed by a board certified veterinary radiologist for the presence and degree of pharyngeal collapse. Results demonstrate that pharyngeal collapse was significantly more common in brachycephalic dogs (58/82; 72%) than in nonbrachycephalic dogs with (7/25; 28%) and without (2/30; 7%) airway collapse. Pharyngeal collapse is more prevalent in brachycephalic dogs undergoing videofluoroscopy than in dolichocephalic/mesocephalic dogs with or without airway collapse.

Background Drug induced sleep endoscopy (DISE) is hoped to identify reasons of failure of adenotonsillectomy (AT) in treating pediatric sleep disordered breathing (SDB). Maxillomandibular disproportion has been studied as another association which may explain alternative pathogenesis of SDB. We aimed to explore the relation between the size of the gonial angle and inclination of the epiglottis measured from cone beam CT (CBCT) and tongue base collapse based on DISE in children with SDB. Method A retrospective chart review was conducted at a tertiary pediatric center. Children (6-17 years old) assessed at a multi-disciplinary Upper Airway Clinic, diagnosed with SDB and maxillo-mandibular disproportion (MMD), and who underwent DISE were eligible. Variables obtained from the electronic medical records of the clinic and prospective database included demographics, comorbidities, surgeries performed, investigations, DISE findings and CBCT findings. The gonial angle of subjects with and without tongue base collapse (TBC) on SNP were compared. Results In total 29 patients (13 male, 8 female) age 6-17 (median= 9) were eligible for the study from January 2009 – July 2016. We included 11 subjects, and 10 comparators. The mean gonial angle of the TBC group was 139.3°± 7.6°, while that of the comparison group was 129.4°±3.5 (mean difference -9.937, 95% CI of -15.454 to - 4.421, P = 0.001, power of test 0.95). Additionally, the mean inclination of the epiglottis had a mild positive correlation (r=0.32, p

Obstructive sleep apnoea syndrome (OSAS), which is characterised by repetitive episodes of pharyngeal collapse during sleep, is gaining much attention because of the important deleterious consequences it might have on the patient's health. We therefore organised a retrospective longitudinal study to report the long-term follow-up of maxillomandibular advancement (MMA) as a treatment for OSAS. A total of 19 patients with severe OSAS was treated during the period 2007-2016. They were followed up six months postoperatively (T1) and after a mean follow up of 6.7 (range 4-10) years (T2, between November 2017 and February 2018) for the polysomnography variables, and the Epworth sleeping scale (ESS) and body mass index (BMI) were recorded. All polysomnographic variables improved significantly from baseline to T1 and from baseline to T2. The ESS significantly improved from baseline to T2. Nearly all patients at T1 and over two-thirds at T2 had a 50% reduction of the apnoea/hypopnoea index when compared with baseline, and a value lower than 20 of the same index. The BMI did not change significantly from T0 to T2. Our long-term follow-up has documented the stability of the outcomes of the MMA for the treatment OSAS.

To investigate the efficacy of anterolateral advancement pharyngoplasty to enlarge pharyngeal airspace and to decrease palatal and lateral pharyngeal wall collapse in the treatment of obstructive sleep apnea (OSA).Prospective study.University medical hospital.Forty-one patients underwent an anterolateral advancement pharyngoplasty procedure according to the following criteria: body mass index30 kg/m(2), Friedman stage II or III, type I Fujita, nocturnal polysomnography diagnostic of OSA, retropalatal and lateral pharyngeal collapse, and diagnosis with flexible nasoendoscopy during a Müller's maneuver based on a 5-point scale. Patients with retroglossal airway collapse were excluded from the study. The principle of this technique is to advance and fix the palatopharyngeus muscle with the superior pharyngeus constrictor muscle without transecting any of their fascicules anterolateral to the pterygomandibular raphe and anterosuperior to the levator veli palatine muscle.Pre- and postoperative polysomnography findings (mean ± SD) showed significant statistical differences: apnea hypopnea index (AHI) decreased from 42.1 ± 16.34 to 16.3 ± 10.3 (P ≤ .001); percentage of time with oxyhemoglobin saturation90% decreased from 18.5% ± 4.2% to 10.1% ± 1.3% (P ≤ .001); and lowest oxygen saturation level increased from 79.9% ± 14.8% to 89.3% ± 11.1% (P ≤ .05). The mean time for patients to return to a normal diet was 12.2 days. There was no postoperative bleeding, velopharyngeal insufficiency, speech alternations, or taste loss. Based on a threshold of a 50% reduction in AHI and AHI20, surgical success was 86.8%.Anterolateral advancement pharyngoplasty appears to be an effective technique with a high surgical success rate in the treatment of OSA patients with lateral pharyngeal wall collapse.

Obstructive sleep apnea (OSA) is characterized by episodes of pharyngeal collapse during sleep. Craniofacial alterations such as retrognathia are often found in OSA patients. Maxillomandibular advancement (MMA) surgeries increase the pharyngeal space and are a treatment option for OSA. The aim of this study was to present a successful case of MMA surgery in the treatment of OSA. A patient with moderate OSA (apnea-hypopnea index (AHI)=25.2) and mandibular retrognathism and Maxillomandibular asymmetry underwent MMA surgery. The apnea-hypopnea index (AHI) were considerably improved after six months (IAH =6.7) and one year of treatment (IAH=0.2).

Background This pilot study examined airway characteristics during upper endoscopy to determine who is at high risk for obstructive sleep apnea. Methods Patients undergoing routine upper endoscopy were divided into 2 groups according to the Berlin Questionnaire (high and low risk for sleep disordered breathing). Patients underwent routine upper endoscopy using propofol sedation. The airway was then evaluated for no, partial, or complete collapse at the levels of the palate/uvula/tonsils, the tongue base, the hypopharynx, and the larynx. They were given a score of 0 for no collapse, 1 for partial collapse, and 2 for complete collapse. The score for each of these levels was added to give a total score or severity index. The larynx was also evaluated for lateral pharyngeal collapse (minimal, up to 50%, >50%, or 100%). Results We found that patients with a partial obstruction at the level of the palate/uvula/tonsils, tongue base, hypopharynx, or larynx, or complete obstruction at any level more often had a positive Berlin questionnaire. Patients with a positive Berlin questionnaire were more often of increased weight (mean 197 vs 175 lbs, P=0.19), increased body mass index (31.2 vs 27.42 kg/m2, P=0.11), increased neck circumference (36.7 vs 34.7 cm, P=0.23), and had a higher total airway score (2.61 vs 1.67, P=0.09). Conclusions The results of our pilot study represent preliminary data regarding the use of upper endoscopy as a potential tool to evaluate patients for obstructive sleep apnea. Keywords Upper endoscopy, sleep apnea, Berlin questionnaire, airway Ann Gastroenterol 2016; 29 (4): 481-486

Obstructive sleep apnoea (OSA) is a common sleep disorder, characterized by complete or partial airway obstruction and caused by pharyngeal collapse during sleep. The resultant complete cessations of breathing are called apnoeas if their duration is 10 s or more. Hypopnoeas are a result of reduced inspiratory flow when the airway narrows but does not fully collapse (Strollo and Rogers 1996).

We present the case of a patient who was diagnosed with chronic bronchitis, obstructive sleep apnoea syndrome, and large Reinke laryngeal oedemas that were removed by transoral laser microsurgery. In the immediate post-operative period acute respiratory insufficiency occurred due to pharyngeal collapse that required emergency re-intubation, after which the patient was transferred to the ICU where mechanical ventilation was given for 18h. Subsequent progress was normal. We describe the combination of various risk-factors related to anaesthetic management and the importance of considering each one of them, especially the preoperative detection of the severity of obstructive sleep apnoea syndrome.

Background Obstructive sleep apnea (OSA) relates to overnight rostral fluid shift, possibly because fluid accumulation around the pharynx increases pharyngeal resistance (Rph). We hypothesised that Rph will increase more in men with than without OSA in response to rostral fluid redistribution. Methods Seventeen men with, and 12 without OSA were randomized to lower body positive pressure (LBPP) for 15 min or control, then crossed over. Leg fluid volume (LFV) and Rph were measured before and after each period. Results LBPP displaced similar amounts of fluid from the legs in both groups. However, compared to the non-OSA group, Rph increased significantly more during LBPP in the OSA group (−0.38 ± 2.87 vs. 2.52 ± 2.94 cmH2O/l/s, p = 0.016). Change in Rph during LBPP correlated directly with baseline Rph in the OSA group, but inversely in the non-OSA group. Conclusion OSA patients have increased susceptibility to pharyngeal obstruction in response to rostral fluid redistribution, which could predispose to pharyngeal collapse during sleep.

Aim: There are limited data about the role of sleep endoscopy in obstructive sleep apnea syndrome (OSAS). The aim of this study was to evaluate the level, degree and shape of obstruction of the upper airway in patients with OSAS by sleep endoscopy and their relation to OSAS severity. Patients and methods: Fifty consecutive patients with OSAS were prospectively enrolled in this cross sectional analytic study. All patients underwent history, a full night-attended polysomnography and sleep endoscopy. The degree of pharyngeal narrowing (grades I–IV) was evaluated at retropalatal, retroglossal and hypopharyngeal levels. Shape of pharyngeal collapse was classified into circular, lateral or antero-posterior at retropalatal and retroglossal levels. Shape of the epiglottis was also observed. Results: All patients showed multisegmental levels of obstruction. Moderate OSAS had a higher percentage of grade II obstruction but a lower percentage of grade I at hypopharyngeal level compared to mild OSAS (P

Reasons for performing the study: Endoscopic examination of Thoroughbred (TB) yearlings is performed routinely to determine the suitability of horses for racing and to ensure that the conditions of sale are satisfied. However, previous research has demonstrated that resting endoscopic examination can be inaccurate in the diagnosis of functional pathology of the upper portion of the respiratory tract (URT). Objectives: To investigate the feasibility of performing dynamic overground endoscopy in a group of TB yearlings and to compare the results of resting and dynamic endoscopic examination of the URT. Study design: Prospective cohort study. Methods: Resting (pre- and post exercise) and exercising endoscopy was performed on 57 TB yearlings at a single training yard. Observed abnormalities were recorded and graded. The results of resting and dynamic examination were compared. Results: Dynamic overground endoscopy was well tolerated and was performed with few complications. Laryngeal asymmetry (29 cases) was the most common abnormality identified at rest, while intermittent dorsal displacement of the soft palate (IDDSP; 19 cases) was the most common at exercise. Significant variation in laryngeal function and variation in the occurrence of IDDSP was noted between examinations. Other potentially significant pathology that was not noted at rest but was present during exercise included collapse of the apex of the corniculate process, pharyngeal collapse and cricotracheal ligament collapse. The occurrence of IDDSP at exercise was significantly associated with epiglottic structure grade>2 and a recent history of respiratory tract infection. Conclusions: Dynamic overground endoscopy is safe and potentially useful when assessing URT function in TB yearlings. Significant variations in the results of endoscopy at rest and during exercise were identified, which indicate that resting endoscopy may not be sufficient to predict the occurrence of pathology during exercise. Potential relevance: Dynamic overground endoscopic examination could be considered a suitable means of assessing URT function in TB yearlings and may provide additional pertinent information to that obtained during standard resting examination.

Obstructive sleep apnoea occurs during sleep, when there is repeated pharyngeal collapse obstructing the airway, and causing repeated awakenings from sleep. Sufferers complain of unrefreshing sleep and daytime somnolence, and bed partners usually report snoring with frequent apnoeic attacks. Problems with tasks requiring concentration, such as driving, are common, and in severe sleep apnoea the rate of road traffic accidents secondary to sleepiness is known to be high. Investigation with a sleep study is required to confirm the diagnosis and severity before the decision is made to initiate life-long treatment with nasal continuous positive airway pressure treatment. Milder cases may respond to a jaw advancement device, and weight loss.

Purpose of review Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent pharyngeal collapse secondary to sleep-induced hypotonia of peri-pharyngeal structures. Therapy for OSA is sometimes poorly tolerated and not always effective. The current study reviews a new treatment modality, hypoglossus stimulation, recently evaluated by multiple physiological studies and currently assessed by several clinical studies. Recent findings A phase-I, implantable hypoglossus nerve stimulation multicenter study was published in 2001. Significant reduction in apnea-hypopnea index (AHI) was reported in seven of the eight implanted OSA patients, but technical faults precluded prolonged follow-up. Over the past 2 years, three new hypoglossus nerve stimulation systems have been evaluated in more than 60 OSA patients. In adequately selected patients, a more than 50% reduction in AHI was observed. Usually, a decrease in OSA severity from moderate-severe to mild-minimal can be achieved. Summary Ongoing research, including recent initiation of a large multicenter phase-III study, suggests that hypoglossus nerve stimulators are likely to be available as a new treatment modality within a few years. Additional data are needed to define which OSA patients are most likely to benefit from hypoglossus nerve stimulation. Continuous refinement of electrodes design is likely to improve stimulation efficacy in coming years.

In patients with neuromuscular disorders, no randomized studies have been performed whether nasal or oronasal masks should be preferred. Oronasal masks are often used in acute respiratory failure, while nasal masks are preferred in patients with chronic respiratory failure. However, the use of nasal masks can result in mouth leaks with implications on sleep quality. To reduce these leaks, oronasal masks have been applied during home noninvasive ventilation (NIV). Until now, upper airway obstruction during NIV has been thought to be induced by nasal obstruction, pharyngeal collapse, and/or glottis closure. We report a case indicating another cause of upper airway obstruction: use of an oronasal mask can induce obstructive events in the upper airways, possibly resulting in sleep fragmentation and decreased efficiency of NIV.

This study is a preliminary test of the hypothesis that the pathophysiology of irritable bowel syndrome (IBS) derives from pharyngeal collapse during sleep.We studied inspiratory airflow dynamics during sleep in 12 lean females with IBS and 12 healthy female controls matched for age and obesity. A standard clinical polysomnogram (airflow measured with a nasal/oral pressure catheter) was performed to assess the impact of pharyngeal collapse on the participants' natural sleep. A second polysomnogram with a pneumotachograph and a supraglottic pressure catheter to measure airflow and effort was performed to compare the maximal inspiratory airflow and effort and the prevalence of inspiratory airflow limitation (IFL) during supine stage 2 sleep between groups.During clinical polysomnography, IBS participants did not differ significantly from controls in sleep architecture or respiration. The difference in apnea-hypopnea index between IBS participants and controls, however, approached statistical significance (2.8 +/- 2.7 vs 1.1 +/- 1.5, respectively; p = 0.079). Although nine of the 12 IBS participants had a prevalence of IFL of at least 33% during supine stage 2 sleep, they did not differ from controls in maximal inspiratory airflow, inspiratory effort, or the prevalence of IFL. Controls, however, differed from IBS participants in having their prevalence of IFL during stage 2 sleep positively correlated with age (r = 0.86; p = 0.0003) while IBS participants demonstrated no relationship between the prevalence of IFL and age.Our findings, while less than definitive, suggest a prevalence pattern of pharyngeal collapse during sleep among females with IBS that differs from that of healthy females, providing necessary background to inform further work on the relationship of pharyngeal collapse during sleep to IBS.

Mechanical processes underlying pharyngeal closure have not been examined. We hypothesized that the pharyngeal mucosal surface would fold during closure, and lowering the upper airway lining liquid surface tension would unfold areas of mucosal apposition, i.e., folds. We compared baseline pharyngeal fold numbers and response to reduction in upper airway liquid surface tension in healthy and obstructive sleep apnea (OSA) subjects. Awake, gated magnetic resonance pharyngeal airway images of 10 healthy and 11 OSA subjects were acquired before and after exogenous surfactant administration (beractant). Upper airway liquid surface tension was measured at the beginning and end of image acquisition and averaged. Velopharyngeal and oropharyngeal images were segmented and analyzed separately for average cross-sectional area, circumference, and fold number. Compared with healthy subjects, at baseline, velopharynx for OSA subjects had a smaller cross-sectional area (98.3 ± 32.5 mm2 healthy, 52.3 ± 23.6 mm2 OSA) and circumference (46.5 ± 8.1 mm healthy, 30.8 ± 6.1 mm OSA; both P < 0.05, unpaired t-test), and fewer folds (4.9 ± 1.6 healthy, 3.1 ± 1.8 OSA, P < 0.03). There were no differences in oropharynx for cross-sectional area, circumference, or folds. Reduction in upper airway liquid surface tension from 61.3 ± 1.2 to 55.3 ± 1.5 mN/m ( P < 0.0001) did not change cross-sectional area or circumference for velopharynx or oropharynx in either group; however, in OSA subjects, oropharyngeal folds fell from 6.8 ± 3.1 to 4.7 ± 1.2 ( n = 8, P < 0.05), and velopharyngeal folds from 3.3 ± 1.9 to 2.3 ± 1.2 ( P = 0.08), and were unchanged in healthy subjects. Subjects with OSA have fewer velopharyngeal wall folds, which decrease further when surface tension falls. We speculate that reduced pharyngeal wall folds contribute to an increase in pharyngeal collapsibility.

The obstructive sleep apnoea-hypopnoea syndrome (OSAHS) is a sleep-related breathing disorder characterised by repetitive pharyngeal collapse. OSAHS is associated with a reduced quality of life. A high OSAHS prevalence has been reported in patients treated for head and neck cancer (HNC). The aim of the present study was to identify the prevalence of OSAHS within a Dutch population of patients treated for HNC. Consecutive HNC patients with a follow-up of 6 months to 5 years after treatment of an oral or oropharynx carcinoma were eligible for inclusion. Two questionnaires were used to assess the presence of OSAHS-related complaints. Subsequently, polysomnography was used in patients with OSAHS-related complaints to confirm the diagnosis of OSAHS. Four out of 33 included patients were diagnosed with OSAHS, yielding a prevalence of 12%. Since recognition and treatment of OSAHS might play an important role in improving quality of life of HNC patients, we suggest screening all patients with an oral or oropharynx carcinoma for the presence of OSAHS-related complaints prior to and following HNC treatment. (c) 2005 Elsevier Ltd. All rights reserved.

Summary The nasopharynx is a source of several upper airway disorders such as dorsal displacement of the soft palate, pharyngeal lymphoid hyperplasia and pharyngeal collapse. The neuromuscular anatomy of this region is complex and the etiology of these diseases is poorly understood. Recently, progress has been made to understand and elucidate the pathophysiology of these disorders. The aim of this review is to give an overview of the recent advances in this area.

OBJECTIVE: To evaluate repelling magnetic implants to treat obstructive sleep apnea (OSA) using a canine model.STUDY DESIGN AND SETTING: Magnetic forces equivalent to effective CPAP were estimated with benchtop studies. An acute canine model was used to simulate pharyngeal collapse. Tolerance, safety, and stability of the implants were evaluated in a chronic series of 10 dogs observed over 6 months.RESULTS: Equivalence to CPAP (10-12 cm H20) was achieved with low-force (

Obstructive sleep apnea (OSA) is a common disease with important neurocognitive and cardiovascular sequelae. Existing therapies are unsatisfactory, leading investigators to seek alternative forms of anatomic manipulation to influence pharyngeal mechanics. We have developed a two-dimensional computational model of the normal human upper airway based on signal averaging of MRI. Using the finite element method, we can perform various anatomic perturbations on the structure in order to assess the impact of these manipulations on pharyngeal mechanics and collapse. By design, the normal sleeping upper airway model collapses at − 13 cm H2O. This closing pressure becomes more negative (ie, less collapsible) when we perform mandibular advancement (− 21 cm H2O), palatal resection (− 18 cm H2O), or palatal stiffening (− 17 cm H2O). Where clinical data are available in the literature, the results of our model correspond reasonably well. Furthermore, our model provides information regarding the site of obstruction and provides hypotheses for clinical studies that can be undertaken in the future (eg, combination therapies). We believe that, in the future, finite element modeling will provide a useful tool to help advance our understanding of OSA and its response to various therapies.

Background It is still subject to controversy if an increased vertical opening (VO) is beneficial in oral appliance therapy for the treatment of obstructive sleep apnoea. Each oral appliance has a given thickness causing VO. Therefore, evaluation of the effects of the amount of VO on pharyngeal dimensions is mandatory. Methods The effects of VO on the cross-sectional area of the upper airway at the level of the tongue base during sleep endoscopy were scored and categorised. Results The figures demonstrate the possible effects of VO on pharyngeal collapse relative to the baseline cross-sectional area and the maximal comfortable protrusion of the mandible. Thirty-two patients (80%) showed an adverse effect of VO ( Fig. 1 ), one patient (2.5%) had a positive effect ( Fig. 2 ), and seven patients (17.5%) demonstrated an indifferent effect ( Fig. 3 ). Conclusion Based on literature, the effect of VO on pharyngeal collapse is unclear and the therapeutic impact of VO is not determined. The results of the present study indicate that the effect of VO on the degree of pharyngeal collapse as assessed during sleep endoscopy tends to be adverse, causing an increase in collapsibility in the majority of patients.

It is well recognized that airflow obstruction in obstructive sleep apnea is caused by collapse of the pharynx. Although the precise anatomic and structural factors leading to pharyngeal collapse are not known, it is generally appreciated that collapse is caused by a complex interaction of structural and neuromuscular factors. The pharynx is comprised of numerous anatomic structures. Its properties are modulated dynamically by neural activation of its musculature. This neuromuscular control is required to integrate the normal functions of the pharynx in respiration, alimentation, and speech. In obstructive sleep apnea, however, such control goes awry as pharyngeal collapse interferes with its normal respiratory function during sleep. This article examines the underlying mechanisms for pharyngeal collapse in apneic patients and their therapeutic implications.

The goal of the project is to investigate new computational tools for understanding normal upper airway mechanics and the pathophysiology of obstructive sleep apnea (OSA), a disorder characterized by repetitive pharyngeal collapse and occlusion during sleep. To relate the airway mechanical parameters to anatomy, and explore the roles of primary muscle properties, airway shape and structure, a new computational system for modeling of rat upper airway passive mechanics based on magnetic resonance imaging (MRI) was developed. The model is capable of computing stress and strain distributions under arbitrary loading, and dynamic animation of three-dimensional airway motion.

Sleep disordered breathing is a common condition within the general community. Mostly this is represented by obstructive sleep apnoea (OSA), a condition characterized by repetitive occlusions of the upper airway due to retro-positioning of the tongue and pharyngeal collapse during sleep. This article covers the key evidence relating OSA to both causation and progression of congestive heart failure and cardiovascular disease including hypertension. The results of recent studies are summarized, and the authors conclude that whilst progress has been made, there remain many gaps in our knowledge in relation to the contribution to the burden of cardiac disease produced by associated conditions such as OSA. Larger studies with important primary endpoints will be required to demonstrate the merit of screening and treating this disorder.