FACE study: 2-year follow-up of adaptive servo-ventilation for sleep-disordered breathing in a chronic heart failure cohort.

BACKGROUND: Sleep-disordered breathing (SDB) is a common comorbidity in patients with heart failure (HF) and is associated with worse prognosis. OBJECTIVES: This study evaluated the effects of adaptive servo-ventilation (ASV) on morbidity and mortality in a large heterogeneous population of HF patients with different etiologies/phenotypes. METHODS: Consecutive HF patients with predominant central sleep apnea (± obstructive sleep apnea) indicated for ASV were included; the control group included patients who refused or stopped ASV before three months follow-up. Six homogenous clusters were determined using the latent class analysis (LCA) method. The primary endpoint was time to composite first event (all-cause death, lifesaving cardiovascular intervention, or unplanned hospitalization for worsening of chronic HF). RESULTS: Of 503 patients at baseline, 324 underwent 2-year follow-up. Compared to control group, 2-year primary endpoint event-free survival was significantly greater in patients in ASV group only in univariable analysis (1.67, 95% [1.12-2.49]; p = 0.01). Secondary endpoints, event-free of cardiovascular death or heart failure-related hospitalization and all-cause death or all-cause hospitalization were positively impacted by ASV (univariate and multivariable analysis). LCA identified two groups, with preserved and mid-range left ventricular ejection fraction (LVEF) and severe hypoxia, in whom ASV increase prognosis benefit. CONCLUSIONS: Patients with HF and SDB are a highly heterogeneous group identified using LCA. Systematic deep phenotyping is essential to ensure that ASV is prescribed to those benefit from therapy, as ASV use in patients with severe hypoxic burden and those with HFpEF was associated with a significant reduction in cardiovascular events and mortality. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01831128.

Quantitative Measurement of Pharyngeal Dimensions During Drug-induced Sleep Endoscopy for Oral Appliance Outcome.

OBJECTIVE: To quantitatively investigate the effect of mandibular advancement devices (MADs) on pharyngeal airway dimensions in a transverse plane as measured during drug-induced sleep endoscopy (DISE). METHODS: Data from 56 patients, treated with MAD at 75% maximal protrusion and with baseline Apnea-Hypopnea Index ≥10 events/h, were analyzed. For each patient, three snapshots were selected from DISE video footage at baseline, with MAD presence, and during chin lift, resulting in 498 images (168/168/162, baseline/MAD/chin lift). Cross-sectional areas, anteroposterior (AP) and laterolateral (LL) dimensions on both retroglossal and retro-epiglottic levels were measured. To define the effect of MAD and chin lift on pharyngeal dimensions, linear mixed-effect models were built. Associations between MAD treatment response and pharyngeal expansion (MAD/chin lift) were determined. RESULTS: Significant differences were found between retroglossal cross-sectional areas, AP, and LL dimensions at baseline and with MAD presence. At a retro-epiglottic level, only LL dimensions differed significantly with MAD presence compared to baseline, with significant relation of LL expansion ratio to treatment response (p = 0.0176). After adjusting the response definition for the sleeping position, greater retroglossal expansion ratios were seen in responders (1.32 ± 0.48) compared to non-responders (1.11 ± 0.32) (p = 0.0441). No significant association was found between response and pharyngeal expansion by chin lift. CONCLUSION: Our observations highlight the additional value of quantitative pharyngeal airway measurements during DISE with MAD presence in evaluating MAD treatment outcome. These findings demonstrate an increase in retroglossal airway dimensions during DISE, with MAD presence, and more pronounced increase in retroglossal expansion ratios in MAD treatment responders compared to non-responders after sleeping position correction. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:3619-3627, 2023.

Multimodal phenotypic labelling using drug-induced sleep endoscopy, awake nasendoscopy and computational fluid dynamics for the prediction of mandibular advancement device treatment outcome: a prospective study.

Mandibular advancement device (MAD) treatment outcome for obstructive sleep apnea (OSA) is variable and patient dependent. A global, clinically applicable predictive model is lacking. Our aim was to combine characteristics obtained during drug-induced sleep endoscopy (DISE), awake nasendoscopy, and computed tomography scan-based computational fluid dynamic (CFD) measurements in one multifactorial model, to explain MAD treatment outcome. A total of 100 patients with OSA were prospectively recruited and treated with a MAD at fixed 75% protrusion. In all, 72 underwent CFD analysis, DISE, and awake nasendoscopy at baseline in a blinded fashion and completed a 3-month follow-up polysomnography with a MAD. Treatment response was defined as a reduction in the apnea-hypopnea index (AHI) of ≥50% and deterioration as an increase of ≥10% during MAD treatment. To cope with missing data, multiple imputation with predictive mean matching was used. Multivariate logistic regression, adjusting for body mass index and baseline AHI, was used to combine all potential predictor variables. The strongest impact concerning odds ratios (ORs) was present for complete concentric palatal collapse (CCCp) during DISE on deterioration (OR 28.88, 95% confidence interval [CI] 1.18-704.35; p = 0.0391), followed by a C-shape versus an oval shape of the soft palate during wakefulness (OR 8.54, 95% CI 1.09-67.23; p = 0.0416) and tongue base collapse during DISE on response (OR 3.29, 95% CI 1.02-10.64; p = 0.0464). Both logistic regression models exhibited excellent and fair predictive accuracy. Our findings suggest DISE to be the most robust examination associated with MAD treatment outcome, with tongue base collapse as a predictor for successful MAD treatment and CCCp as an adverse DISE phenotype.

Endotypic Mechanisms of Successful Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea.

Rationale: Approximately one-third of patients with obstructive sleep apnea (OSA) treated with hypoglossal nerve stimulation (HGNS) therapy are incomplete responders, despite careful patient selection based on baseline characteristics and drug-induced sleep endoscopy.Objectives: Here we use polysomnographic endotyping to assess the pathophysiological mechanisms underlying favorable versus incomplete responses to HGNS therapy.Methods: Baseline polysomnography data of the STAR (Stimulation Therapy for Apnea Reduction) trial were included. Raw baseline polysomnographic data from 91/126 patients were available for analysis. Traits-loop gain, arousal threshold, collapsibility, and muscle compensation-were calculated from the baseline polysomnography data according to Sands and colleagues (AJRCCM 2018, SLEEP 2018). Logistic regression assessed apnea-hypopnea index (AHI)-adjusted associations between HGNS response (>50% reduction in AHI to <10/h at 1 yr) and OSA traits.Measurements and Main Results: Overall, HGNS treatment reduced AHI from 30.7 (24.9-39.9) to 8.5 (4.0-19.5) events/h (P < 0.0001; median [quartiles 1-3]); N = 53/91 were responders. In adjusted analysis, a favorable response to therapy was independently associated with higher arousal threshold (odds ratio [95% confidence interval]: 6.76 [2.44-23.3], P = 0.001), greater compensation (odds ratio: 4.22 [1.70-12.55] per SD, P = 0.004), and lower loop gain (in milder collapsibility, per significant interaction, P = 0.003). The higher arousal threshold was evident in responders before adjusted analysis. Predicted responders had an approximately fourfold lower treatment AHI versus predicted nonresponders (4.9 [2.7-8.5] vs. 20.7 [10.9-29.7], P < 0.0001; median [quartiles 1-3]); differences remained significant after cross-validation.Conclusions: Favorable responses to HGNS therapy are associated with the pathophysiological traits causing OSA, particularly a higher arousal threshold. Along with established criteria, individuals with favorable traits could potentially be prioritized for precision HGNS therapy.This analysis was a secondary analysis of the STAR trial registered with clinicaltrials.gov (NCT01161420).

Cohort profile: FACE, prospective follow-up of chronic heart failure patients with sleep-disordered breathing indicated for adaptive servo ventilation.

PURPOSE: FACE is a prospective cohort study designed to assess the effect of adding adaptive servoventilation (ASV) to standard care on morbidity and mortality in patients with chronic heart failure (HF) with preserved (HFpEF), mid-range (HFmrEF) or reduced ejection fraction (HFrEF) who have sleep-disordered breathing (SDB) with an indication for ASV. We describe the study design, ongoing data collection and baseline participant characteristics. PARTICIPANTS: Consecutive patients with HFpEF, HFmrEF or HFrEF plus SDB with central sleep apnoea (CSA) and indication for ASV were enrolled in the study cohort between November 2009 and December 2018; the ASV group includes those treated with ASV and the control group consists of patients who refused ASV or stopped treatment early. Follow-up is based on standard clinical practice, with visits at inclusion, after 3, 12 and 24 months of follow-up. Primary endpoint is the time to first event: all-cause death or unplanned hospitalisation (or unplanned prolongation of a planned hospitalisation) for worsening of HF, cardiovascular death or unplanned hospitalisation for worsening of HF, and all-cause death or all-cause unplanned hospitalisation. FINDINGS TO DATE: 503 patients have been enrolled, mean age of 72 years, 88% male, 31% with HFrEF. HF was commonly of ischaemic origin, and the number of comorbidities was high. SDB was severe (median Apnoea-Hypopnoea Index 42/hour), and CSA was the main indication for ASV (69%). HF was highly symptomatic; most patients were in NYHA class II (38%) or III (29%). FUTURE PLANS: Patient follow-up is ongoing. Given the heterogeneous nature of the enrolled population, a decision was made to use latent class analysis to define homogeneous patient subgroups, and then evaluate outcomes by cluster, and in the ASV and control groups (overall and within patient clusters). First analysis will be performed after 3 months, a second analysis at the 2-year follow-up. TRIAL REGISTRATION NUMBER: NCT01831128; Pre-results.

Correction to: Remotely controlled mandibular positioning of oral appliance therapy during polysomnography and drug-induced sleep endoscopy compared with conventional subjective titration in patients with obstructive sleep apnea: protocol for a randomized crossover trial.

Following publication of the original article [1], the authors reported that Fig. 1 had not been corrected based on the reviewer's comments. The correct Fig. 1 is presented below.

Drug-Induced Sleep Endoscopy: Evaluation of a Selection Tool for Treatment Modalities for Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is a very common disorder with important day and nighttime symptoms and long-term effects on health. Different treatment modalities such as positive airway pressure (PAP), oral appliance therapy using custom-made, titratable mandibular advancement devices (MAD), different types of surgery and positional therapy have been introduced over the years, with patient preference and adherence to therapy being key elements in improving treatment outcomes. Several patient selection tools to improve treatment outcomes have been introduced and evaluated over the years. Drug-induced sleep endoscopy (DISE) is a procedure that provides real-time upper airway evaluation of the sites of flutter and upper airway collapse. This review focuses on the indications and contraindications for DISE, methods of sedation and evaluation, add-on maneuvers, and the results on patient selection and treatment outcomes. A PICO approach was used to clarify the aims of this review. DISE has the advantage of being easily accessible in most ENT practices and being 3-dimensional, dynamic, site specific, safe and it is valuable in selecting patients for upper airway surgery and oral appliance therapy. There is a strong interest for further standardization and exploration of the predictive value of this evolving technique.

Remotely controlled mandibular positioning of oral appliance therapy during polysomnography and drug-induced sleep endoscopy compared with conventional subjective titration in patients with obstructive sleep apnea: protocol for a randomized crossover trial.

BACKGROUND: The amount of mandibular protrusion is a key factor in optimizing the efficacy of mandibular advancement device (MAD) therapy in an individual patient diagnosed with obstructive sleep apnea. This process is called titration and is generally based on resolution of subjective symptoms like snoring and/or daytime sleepiness as a function of protrusion. An objective approach uses a remotely controlled mandibular positioner (RCMP) during a full-night polysomnography (PSG), in analogy with continuous positive airway pressure (CPAP) titration. More recently, the feasibility of RCMP use during drug-induced sleep endoscopy (DISE) titration was reported. METHODS: This randomized crossover trial will compare DISE-assisted titration to PSG-guided titration, as well as with the conventional subjective titration method. The primary outcome is the actual mandibular protrusive position found to be the most optimal for each tested titration procedure. Furthermore, the therapeutic efficacy will be compared among the different titration modalities using level 1 sleep studies. DISCUSSION: Currently, the optimal titration of MAD therapy is most often based on 'trial and error'. The conventional method relies on subjective improvement in symptoms, although this may not provide the most accurate indicator for efficient titration. Therefore, relying on objective criteria in the titration process should be advantageous. In analogy with CPAP, titration of the most optimal mandibular protrusion could be performed using RCMP during an overnight titration PSG. Recently, it was shown that titration under direct visualization of upper airway patency and collapsibility is feasible using the RCMP during DISE. However, no clinical results for such a procedure are as yet available. This study is the first to compare the most optimal mandibular protrusive position according to three titration procedures, as well as to compare the therapeutic efficacy of these titration methods. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03716648 . Registered on 23 October 2018.

Use of the Clinical Global Impression scale in sleep apnea patients - Results from the ESADA database.

OBJECTIVE/BACKGROUND: The Clinical Global Impression scale (CGI) reflects the clinician's assessment of the disease impact on patient's global functioning. We assessed predictors of CGI scale rating in patients with obstructive sleep apnea (OSA). PATIENTS/METHODS: Consecutive patients with suspected OSA (n = 7581) were identified in the European Sleep Apnea Database (ESADA). Anthropometrics, comorbidities, apnea severity obtained by polygraphy or polysomnography, and daytime sleepiness [Epworth Sleepiness Scale (ESS)] were assessed. The CGI 7-point scale was completed at the end of the diagnostic process (CGI-severity, ie, CGI-S) and, in a subpopulation, at treatment follow-up (CGI-Improvement). RESULTS: CGI-S was rated mild to moderate in 44% of patients. CGI rating at any given apnea intensity was worse in women than in men (p < 0.01). Patients undergoing polygraphy (n = 5075) were more frequently rated as severely ill compared to those studied with polysomnography (19.0% vs 13.0%, p < 0.001). In patients aged ≤65 years, CGI scoring was generally better than in the elderly despite a similar degree of OSA (eg, 'normal, not ill' 24.2% vs 15.3%, p < 0.01, respectively). Independent predictors of CGI rating included age, BMI, AHI, ESS, cardio-metabolic comorbidities, and diagnosis based on polygraphy. CGI-improvement rating (Beta = -0.406, p < 0.01) was superior to sleep apnea severity or ESS-score (Beta = 0.052 and -0.021, p = 0.154 and 0.538 respectively) at baseline for prediction of good CPAP compliance at follow-up. CONCLUSIONS: CGI rating is confounded by gender, age class and the type of sleep diagnostic method. As OSA phenotypes differ, CGI may contribute as a clinical tool to reflect the significance of clinical disease.

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.

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.

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.

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.

Quantification of pharyngeal patency in patients with sleep-disordered breathing.

Many techniques are available for the assessment of pharyngeal characteristics in sleep-disordered breathing (SDB). However, most of the reported techniques are invasive to some extent and/or hard to perform during sleep studies. The focus of this concept paper is on the forced oscillation technique (FOT) to quantify pharyngeal patency in patients with SDB. In a pilot study, the potential of FOT for non-invasive and continuous assessment of pharyngeal patency during different types of respiratory events was studied in 8 patients with an established diagnosis of a sleep apnea-hypopnea syndrome. During polysomnography, FOT was applied using a 5-Hz pressure oscillation signal. The respiratory impedance was determined and considered as a marker for pharyngeal patency. The results demonstrate that FOT allows detection of the complete pharyngeal occlusion during obstructive sleep apnea. In addition, we found that central sleep apnea can be associated with pharyngeal closure. We also demonstrated that during the flow-limited breath preceding obstructive apnea, almost complete upper airway closure can occur during either the expiratory or the inspiratory phase. FOT is a suitable method to assess pharyngeal patency continuously and non-invasively during sleep. Furthermore, this technique has the potential to contribute substantially to our knowledge of upper airway physiology in SDB.

Pilot study of a novel mandibular advancement device for the control of snoring.

OBJECTIVE: Mandibular advancement devices (MADs) have been introduced as a conservative, non-invasive treatment for socially disturbing snoring and mild obstructive sleep apnea (OSA). A prospective, non-randomized pilot study was conducted to investigate the efficacy, feasibility, side-effects and compliance of Somnoguard, an immediately intraorally adaptable MAD made from thermoplastic material. MATERIAL AND METHODS: Twenty consecutive heavy snorers with a respiratory disturbance index of <20 events/h were prospectively selected. Prior to the adaptation of the appliance, ambulatory polygraphy was carried out without a MAD. After a 1-month habituation period, a polygraphic evaluation was carried out with the device. Treatment success was defined as a reduction in the apnea-hypopnea index (AHI) of at least 50%. RESULTS: The results indicated a success rate of 65%. The AHI decreased from 8.4 +/- 2.9 events/h at baseline to 3.9 +/- 1.8 events/h with the device (p = 0.001). At 1-month follow-up, significant reductions in the snoring index (p < 0.001) and the Epworth Sleepiness Scale (ESS) score (p = 0.036) were noted. At 6-month follow-up, similar results were achieved, with significant drops in the snoring index (p = 0.025) and ESS score (p = 0.033). CONCLUSION: We conclude that immediate intraoral adaptation of a low-cost fabricated "one-size-only" MAD is a feasible and well-tolerated treatment for snoring and mild OSA. Further research is needed to evaluate this thermoplastic appliance as a strategy to "screen" the efficacy of MAD treatment in the individual patient with a less expensive appliance before constructing a more expensive custom-made MAD.