Comparative effects of two oral appliances on upper airway structure in obstructive sleep apnea

Cone beam computed tomography changes upon oral appliance therapy for adult patients with obstructive sleep apnea: A non-randomized clinical trial

BACKGROUND

Obstructive sleep apnea (OSA) is caused by narrowing or obstruction of the airway lumen at single or multiple levels of the airway, starting from the nasal cavity up to the larynx. Oral appliance therapy for the management of OSA is prescribed as an alternative treatment option for patients with mild to moderate OSA who fail to adhere to Continuous Positive Airway Pressure (CPAP) therapy. Treatment with oral appliances addresses the craniofacial deficiencies that cause OSA by providing means to mandibular advancement and palatal expansion, thus opening the airways and potentially preventing airway collapse during sleep. Imaging the upper airway is employed to investigate the narrowing or the obstruction in the airway. Three-dimensional imaging modalities such as cone beam computed tomography (CBCT) allow for detecting obstructions before commencing treatment and for evaluating changes in the upper airway dimensions after treatment. To evaluate the effect of the biomimetic oral appliance therapy (BOAT) device on the airway measurements taken from a CBCT before and after treatment in correlation with the changes in the AHI.

TRIAL DESIGN

A non-randomized clinical trial.

METHODS

About 17 patients with mild-moderate OSA (9 males, 8 females; age, mean [SD]: 45.76 [10.31]) underwent BOAT therapy. Subjects had 2 months of follow-up visits, including examinations for progress and adjustment of the appliances. The mean apnea-hypopnea index (AHI) with no appliance in the mouth before BOAT and after treatment was recorded. The midpalate screw mechanism of the appliance was advanced once per week. The subjects were asked to wear the appliance for 10 to 12 h/d and night. Pre and Post CBCT were taken. Paired T-test was used to analyze the results.

RESULTS

The treatment duration was 15.4 ± 6.3 months. Before treatment, at the diagnosis stage, the mean AHI of the sample (n = 17) was 24.0. After treatment, the mean AHI fell by 5% to 22.8% (P = .019), indicating enhanced upper airway functions. Airway measurements from the CBCT were not statistically significant despite improvement in the polysomnographic parameters.

CONCLUSION

CBCT is a valuable tool for airway assessment and the determination of upper airway anatomic risk factors for OSA.

Exploring hypoglossal nerve stimulation therapy for obstructive sleep apnea: A comprehensive review of clinical and physiological upper airway outcomes

Obstructive sleep apnea (OSA) is a chronic disorder characterized by recurrent episodes of upper airway collapse during sleep, which can lead to serious health issues like cardiovascular disease and neurocognitive impairments. While positive airway pressure serves as the standard treatment, intolerance in some individuals necessitates exploration of alternative therapies. Hypoglossal nerve stimulation (HGNS) promises to mitigate OSA morbidity by stimulating the tongue muscles to maintain airway patency. However, its effectiveness varies, prompting research for optimization. This review summarizes the effects of HGNS on upper airway obstruction from human and animal studies. It examines physiological responses including critical closing pressure, maximal airflow, nasal and upper airway resistance, compliance, stiffness, and geometry. Interactions among these parameters and discrepant findings in animal and human studies are explored. Additionally, the review summarizes the impact of HGNS on established OSA metrics, such as the apnea-hypopnea index, oxygen desaturation index, and sleep arousals. Various therapeutic modalities, including selective unilateral or bilateral HGNS, targeted unilateral HGNS, and whole unilateral or bilateral HGNS, are discussed. This review consolidates our understanding of HGNS mechanisms, fostering exploration of under-investigated outcomes and approaches to drive advancements in HGNS therapy.

A systematic review on 4D images of the upper airway in patients with OSA

AIM-BACKGROUND

In the treatment of obstructive sleep apnoea (OSA), oral appliances are now being recognized as a valuable alternative to continuous positive airway pressure (CPAP). Various static imaging techniques of the upper airways allow for assessment of bone and soft tissue structures. However, static images do not capture dynamic airway characteristics. The aim of this paper was to review 4D imaging techniques in patients with OSA.

METHODS

PubMed/MEDLINE, Web of Science and Embase were systematically searched for studies published before June 2022. The review was compliant with the PRISMA guidelines. The quality of each eligible study was critically evaluated by all four authors independently. Four unique articles with qualitative analyses were retrieved. All included studies had a clear objective/aim, an appropriate endpoint and sufficiently described eligibility criteria.

RESULTS

With dynamic imaging (4D) evaluation of the upper airway, the incidence of upper airway collapsibility due to use of a mandibular advancement device (MAD) was reduced, extraluminal tissue pressure was decreased and the space in the upper airway was increased, notably in the retropalatal and retroglossal areas of the airway. These findings suggest that MADs may be effective for OSA regardless of whether or not the obstruction site is in the velopharynx or oropharynx. However, further investigation of dynamic changes in the upper airway is required to explain the efficacy of OSA treatment and the underlying mechanisms.

A mandibular advancement device associated with lingual control: a new treatment option for obstructive sleep apnea?

PURPOSE

Oral appliances (OA) have become the main alternative to positive pressure airway devices (PAP) for the control of obstructive sleep apnea (OSA). Despite literature support, controversies about the mode of action and the effectiveness of these devices persist. The aim of this study was to evaluate the efficacy of modified mandibular advancement devices (MAD) in patients with OSA who failed treatment with MAD and to evaluate the role of the tongue as a factor in patients who failed treatment with MAD.

MATERIALS AND METHODS

Patients unable to control the apnea-hypopnea index (AHI) using a MAD were subsequently treated with a modified version that included a tongue trimming accessory. The objective was to stabilize the tongue by preventing it from sliding with the consequent collapse of the upper airway (UA). New polysomnography (PSG) was performed with the modified MAD in place.

RESULTS

A total of 20 patients who failed MAD therapy were studied including 15 men (75%) with mean age (± standard deviation) of 58.5 ± 13.1 years and BMI 29.6 ± 5.0 Kg/m2. After installing the tongue trimmer, the number of patients who achieved complete success with the new MAD (AHI < 5) went from 0 to 30% and those who achieved partial success (5 < AHI < 10) went from 0 to 20%. The number of patient responders (AHI reduced by at least 50%) went from 20 to 75%.

CONCLUSION

The results suggest that the tongue, even in the presence of a MAD, may be one of the contributing factors for the collapse of the UA and consequent device ineffectiveness. By stabilizing the tongue through the insertion of a tongue trimmer, the MAD became more effective in many cases.

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.

A Multicenter Prospective Study on the Use of a Mandibular Advancement Device in the Treatment of Obstructive Sleep Apnea

The main objective of this prospective study was the evaluation of 1 mm step titration of mandible advancement in the success of treating obstructive sleep apnea (OSA). For that, a multicenter prospective study was designed to recruit patients with OSA who were eligible to receive a mandibular advancement device. Gradual titration of mandibular advancement (steps of 1 mm) from maximum intercuspidation was performed to determine the optimal mandibular advancement (highest reduction in the apnea-hypopnea index (AHI)). The principal variable was the percentage of patients where a reduction ≥50% of the AHI was achieved at the end of the titration phase. A total of 102 patients participated in this study. Fifty-six percent of the participants were males and 67% had a BMI ≥ 25 kg/m2. Most of the patients (79%) had an age ≥ 50 years and the majority (74%) were either non-smokers or ex-smokers. Excessive daytime sleepiness was reported by 40% of the patients. The mean AHI at baseline was 20.6 ± 12.7 events/h. The mean advancement of the mandible was 3.1 ± 1.6 mm. The device achieved a reduction in the AHI in 93% of the patients and success (≥50% reduction in the AHI) in 69% of the patients. Success was achieved in 50%, 81.6%, and 73.3% of the patients with mild, moderate, and severe OSA, respectively. Decreasing the magnitude of mandibular advancement could be possible by controlling the vertical mouth opening and step-by-step titration.

Effects of mandibular advancement devices on upper airway dimensions in obstructive sleep apnea: responders versus non-responders

STUDY OBJECTIVES

To compare the effects of mandibular advancement device (MAD) therapy on upper airway dimensions between responders and non-responders with mild to moderate obstructive sleep apnea (OSA).

METHODS

Thirty-one participants (21 men and 10 women) with a mean ± SD apnea-hypopnea index (AHI) of 16.6 ± 6.7 events/h, and aged 48.5 ± 13.9 years, were included in this study. Polysomnographic recordings and cone beam computed tomography (CBCT) scans in supine position were performed for every participant at baseline and at 3-month follow-up with their MAD in situ. Responders were defined as having ≥ 50% reduction in baseline AHI with a residual AHI < 10 events/h. The primary outcome variable was the minimal cross-sectional area of the upper airway (CSAmin).

RESULTS

No significant differences were found between responders (n = 15) and non-responders (n = 16) in age, gender distribution, body mass index, and neck circumference (P = 0.06-0.93), nor in AHI and CSAmin (P = 0.40 and 0.65, respectively) at baseline. The changes of the CSAmin with MAD in situ in the responder group were not significantly different compared to those in the non-responder group (P = 0.06).

CONCLUSION

Within the limitations of this study, we conclude that the changes of the upper airway dimensions induced by MADs are not significantly different between responders and non-responders with mild to moderate OSA.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02724865. https://clinicaltrials.gov/ct2/show/NCT02724865.

Comparisons of the effects of two types of titratable mandibular advancement devices on respiratory parameters and upper airway dimensions in patients with obstructive sleep apnea: a randomized controlled trial

OBJECTIVES

To compare the effects of two types of titratable mandibular advancement devices (MADs), namely MAD-H (allowing limited vertical opening) and MAD-S (allowing free vertical opening), on respiratory parameters and upper airway dimensions in patients with mild to moderate obstructive sleep apnea (OSA).

MATERIALS AND METHODS

Patients with mild to moderate OSA (5 ≤ apnea-hypopnea index (AHI) < 30 /h) were randomly assigned to two parallel MAD groups. All MADs were subjectively titrated according to a standardized protocol during a 3-month follow-up. Every patient underwent two polysomnographic recordings, and two cone beam computed tomography scans in supine position: one at baseline and another one after 3 months with the MAD in situ. The primary outcome variables were the AHI in supine position (AHI-supine) and the minimal cross-sectional area of the upper airway in supine position (CSAmin-supine).

RESULTS

A total of 49 patients were recruited, and 31 patients (21 men and 10 women) with a mean (± SD) age of 48.5 (± 13.9) years and a mean AHI of 16.6 (± 6.7) /h completed the study. In the per-protocol analysis, there was no significant difference between MAD-H (n = 16) and MAD-S (n = 15) in their effects on AHI-supine (P = 0.14) and CSAmin-supine (P = 0.59). Similar results were found in the intention-to-treat analysis (P = 0.47 and 0.57, respectively).

CONCLUSIONS

Within the limitations of this study, we conclude that there is no significant difference in the effects of an MAD allowing limited vertical opening and an MAD allowing free vertical opening on respiratory parameters and upper airway dimensions in patients with mild to moderate OSA.

CLINICAL RELEVANCE

MADs allowing limited vertical opening and allowing free vertical opening have similar effects on respiratory parameters and upper airway dimensions in patients with mild to moderate OSA.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02724865. https://clinicaltrials.gov/ct2/show/NCT02724865.

Effectiveness of a Uniquely Designed Oral Appliance on Obstructive Sleep Apnea Control: A Pilot Study

OBJECTIVES

 Obstructive sleep apnea is an inflammatory, chronic, and evolutive disease often needing adequate treatment and follow-up. The oral appliance (OA) is an accepted alternative therapy for obstructive sleep apnea (OSA) control. Due to greater adherence, OA with mandibular advancement (OAm) is being recommended treatment for patients who refuse or do not tolerate continuous positive airway pressure. The mode of action of OAm is to promote the advancement of the mandible or tongue with a subsequent increase in the tone of the pharyngeal muscles and the permeability of the upper airway, but most OAm use conventional models as reference, analogic, or digital, dissociating dental arches of the skull structures.

MATERIALS AND METHODS

 A retrospective longitudinal study of 33 OSA patient treated with a different OAm, that use Camper plane as reference with skull structures for dental arches disocclusion, where polysomnographic, cephalometric measures, and subjective data from questionnaires pre- and post-treatment were assessed and correlated. Descriptive analysis, correlated Chi-square tests, and basic statistics were used. Generalized linear mixed model for repeated measure and post hoc Tukey-Kramer test compares the variables pre- and post-treatment. Shapiro-Wilk test and Pearson's correlation coefficients were used. All statistical tests were set in 5% level of significance.

RESULTS

 Regarding polysomnography data, there was a significant association between apnea hypopnea index (AHI) with oxygen saturation, arousal index (AI) and the maximum heartbeats, and sleep improvement and health risk reduction. Additionally, from cephalometric data, it was found a significant association between the tongue posture with the soft palate, hioyd-C3 and, lower and posterior airway. When both parameters are correlated, there are a significant dependent association with hyoid bone position with AHI and AI. The limitation of this study was the two-dimensional image used without provide volumetric measurements, but this limitation was reduced with the follow-up polysomnography parameters.

CONCLUSION

 In this pilot study, DIORS OAm as an uniquely designed device using Camper plane as a reference for disocclusion was effective in the control of OSA.

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

STUDY OBJECTIVES

Mandibular advancement devices (MADs) are a noninvasive treatment option for patients with obstructive sleep apnea (OSA) and act by increasing the upper airway volume. However, the exact therapeutic mechanism of action remains unclear. The aim of this study was to assess MAD mechanisms using functional imaging that combines imaging techniques and computational fluid dynamics and assess associations with treatment outcome.

METHODS

One hundred patients with OSA were prospectively included and treated with a custom-made MAD at a fixed 75% protrusion. A low-dose computed tomography scan was made with and without MADs for computational fluid dynamics analysis. Patients underwent a baseline and 3-month follow-up polysomnography to evaluate treatment efficacy. A reduction in apnea-hypopnea index ≥ 50% defined treatment response.

RESULTS

Overall, 71 patients completed both 3-month follow-up polysomnography and low-dose computed tomography scan with computational fluid dynamics analysis. MAD treatment significantly reduced the apnea-hypopnea index (16.5 [10.4-23.6] events/h to 9.1 [3.9-16.4] events/h; P < .001, median [quartile 1-quartile 3]) and significantly increased the total upper airway volume (8.6 [5.4-12.8] cm³ vs 10.7 [6.4-15.4] cm³; P = .003), especially the velopharyngeal volume (2.1 [0.5-4.1] cm³ vs 3.3 [1.8-6.0] cm³; P < .001). However, subanalyses in responders and nonresponders only showed a significant increase in the total upper airway volume in responders, not in nonresponders.

CONCLUSIONS

MAD acts by increasing the total upper airway volume, predominantly due to an increase in the velopharyngeal volume. Responders showed a significant increase in the total upper airway volume with MAD treatment, while there was no significant increase in nonresponders. Findings add evidence to implement functional imaging using computational fluid dynamics in routine MAD outcome prediction.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Predicting Therapeutic Outcome of Mandibular Advancement Device Treatment in Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT01532050; Identifier: NCT01532050.

CITATION

Van Gaver H, Op de Beeck S, Dieltjens M, et al. Functional imaging improves patient selection for mandibular advancement device treatment outcome in sleep-disordered breathing: a prospective study. J Clin Sleep Med. 2022;18(3):739-750.

Custom-Made Dual-Functional Oral Appliance for Management of Obstructive Sleep Apneic Completely Edentulous Patient

Continuous positive airway pressure (CPAP) being a gold standard treatment to open the upper airway by application of controlled compressed air is still not a widely accepted mode of treatment among obstructive sleep apnea (OSA) individuals. To improve patency of upper airway space and reduce the risk of sleep apnoea, it is essential to provide mandibular advancement devices (MADs) that could provide non-continuous positive airway pressure (non-CPAP) for patients with OSA. Availability of prefabricated oral appliances (OAs) like MADs, tongue holding devices reduced the chair-side fabrication time but has poor adaptation, excessive salivation, and deprivation of sleep. Customized OAs can overcome these challenges, but their fabrication for an edentulous individual is challenging due to the absence of teeth and the encroachment of tongue space by the device. This clinical report gives an insight into the clinical and technical aspect of fabrication of MAD with tongue retaining space for an edentulous individual with OSA.

The efficacy of a titrated tongue-stabilizing device on obstructive sleep apnea: a quasi-experimental study

STUDY OBJECTIVES

To evaluate the short-term efficacy and self-reported outcomes of tongue-stabilizing device (TSD) therapy as compared to those of mandibular advancement device (MAD) therapy in an adult population diagnosed with obstructive sleep apnea.

METHODS

This study is a parallel, nonrandomized clinical trial of the TSD and MAD therapies. The efficacy of both interventions was evaluated objectively by level 3 home sleep apnea testing and by self-report using the Epworth Sleepiness Scale, the Functional Outcomes of Sleep Questionnaire, the Chalder Fatigue Scale, and the 36-Item Short-Form Health Survey. Adherence and adverse effects were self-reported.

RESULTS

Of the 39 patients who received TSD therapy, 27 managed to adapt and complete the trial and were matched with 26 patients who received MAD therapy. At the 2-month follow-up, the acceptance rate of the TSD therapy was 53.8%. Both patients receiving TSD therapy and patients receiving MAD therapy showed significant improvements in their respiratory event index (P < .05), with no difference between the treatments (P > .05). In those receiving TSD therapy (n = 27), the only self-reported efficacy measure that significantly improved with TSD therapy was the Chalder Fatigue Scale (P < .05). In contrast, all 4 self-reported measures (Epworth Sleepiness Scale, Functional Outcomes of Sleep Questionnaire, 36-Item Short-Form Health Survey, and Chalder Fatigue Scale) showed a significant improvement with MAD therapy.

CONCLUSIONS

This study revealed similar improvements in apneas and oxygen saturation between TSD and MAD therapies. Whereas MAD therapy was a better treatment for obstructive sleep apnea in terms of daytime sleepiness and quality-of-life improvements, TSD therapy had a low treatment acceptance rate.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: The Efficacy of Tongue Stabilizing Device in Patients with Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT02329925; Identifier: NCT02329925; and Registry: ClinicalTrials.gov; Name: Adherence and Preference of Continuous Positive Airway Pressure vs Mandibular Advancement Splints in Obstructive Sleep Apnea Patients: A Randomized Trial (CHOICE); URL: https://clinicaltrials.gov/ct2/show/NCT02242617; Identifier: NCT02242617.

CITATION

Alshhrani WM, Hamoda MM, Okuno K, et al. The efficacy of a titrated tongue-stabilizing device on obstructive sleep apnea: a quasi-experimental study. J Clin Sleep Med. 2021;17(8):1607-1618.

The relationship between specific nasopharyngoscopic features and treatment deterioration with mandibular advancement devices: a prospective study

STUDY OBJECTIVES

The variable efficacy of mandibular advancement device (MAD) treatment necessitates both accessible and accurate methods for patient selection. However, the role of awake nasopharyngoscopy for this purpose remains dubious. We introduced an assessment method based on anatomical upper airway features during tidal breathing for nasopharyngoscopy. The current study aimed to relate these features to MAD treatment outcome.

METHODS

One hundred patients diagnosed with obstructive sleep apnea were prospectively recruited for MAD treatment in a fixed 75% degree of maximal protrusion. Nasopharyngoscopic observations during Müller's maneuver and tidal breathing were recorded both with and without MAD. Treatment outcome, confirmed by 3-month follow-up polysomnography with MAD, was classified as (1) apnea-hypopnea index reduction ≥ 50%, (2) treatment apnea-hypopnea index < 5 events/h, and (3) ≥ 10% increase in apnea-hypopnea index compared with baseline (treatment deterioration).

RESULTS

A complete dataset was obtained in 65 patients. After adjusting for baseline apnea-hypopnea index, body mass index, and supine dependency, the position of the soft palate (odds ratio, 4.0; 95% confidence interval, 1.3-11.8; P = .013) and crowding of the oropharynx (odds ratio, 7.7; 95% confidence interval, 1.4-41.4; P = .017) were related to treatment deterioration. Addition of both features significantly (P = .031) improved the accuracy of baseline models based on clinical measurements alone. Moreover, with the MAD in situ, a posteriorly located soft palate (odds ratio, 9.8; 95% confidence interval, 1.7-56.3; P = .010) and a posteriorly located tongue base (odds ratio, 7.4; 95% confidence interval, 1.5-35.9; P = .013) were associated with treatment deterioration.

CONCLUSIONS

Awake nasopharyngoscopy might be a valuable office-based examination to exclude the risk of treatment deterioration and improve patient selection for MAD treatment.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Predicting Therapeutic Outcome of Mandibular Advancement Device Treatment in Obstructive Sleep Apnea (PROMAD); URL: https://clinicaltrials.gov/ct2/show/NCT01532050; Identifier: NCT01532050.

A consideration of factors affecting palliative oral appliance effectiveness for obstructive sleep apnea: a scoping review

STUDY OBJECTIVES

This scoping review allows physicians, researchers, and others interested in obstructive sleep apnea to consider effectiveness of oral appliances (OAs). The intent is to improve understanding of OA effectiveness by considering morphologic interaction in patients with obstructive sleep apnea.

METHODS

Morphologic and biomechanical criteria for positional alterations of the mandible assessed success rates of OA appliances. Searches of databases (Medline, PubMed, The Cochrane Library, EBSCO) using terms: OA treatment effectiveness and positive and/or negative outcome predictors. Craniofacial predictors of OAs and obstructive sleep apnea biomechanical factors of anatomical traits associated with OA effectiveness were included. Databases searched radiographic cephalometric imaging for morphology/phenotypes and apnea-hypopnea index responses. Articles were excluded if title or abstract was not relevant or a case report. If the analysis did not report mean or standard deviation for apnea-hypoxia index, it was excluded. No language, age, or sex restrictions were applied.

RESULTS

Analysis of 135 articles included in searched literature indicated alterations in musculature and pharyngeal airway structure through OA use. These alterations were individually unpredictable with wide variability 61.81% ± 12.29 (apnea-hypoxia index mean ± standard deviation). Morphologic variations as predictors were typically weak and idiosyncratic. Biomechanical factors and wide variations in the metrics of appliance application were unclear, identifying gaps in knowledge and practice of OAs.

CONCLUSIONS

An integrated basis to identify morphologic and biomechanical elements of phenotypic expressions of sleep-disordered breathing in the design and application of OAs is needed. Current knowledge is heterogeneous and shows high variability. Identification of subgroups of patients with obstructive sleep apnea responding to OAs is needed.

The Emerging Role of Drug-Induced Sleep Endoscopy in the Management of Obstructive Sleep Apnea

Obstructive sleep apnea is a prevalent sleep disorder characterized by partial or complete obstruction of the upper airway. Continuous positive airway pressure is the first-line therapy for most patients, but adherence is often poor. Alternative treatment options such as mandibular advancement devices, positional therapy, and surgical interventions including upper airway stimulation target different levels and patterns of obstruction with varying degrees of success. Drug-induced sleep endoscopy enables the visualization of upper airway obstruction under conditions mimicking sleep. In the era of precision medicine, this additional information may facilitate better decision-making when prescribing alternative treatment modalities, with the hope of achieving better adherence and/or success rates. This review discusses the current knowledge and evidence on the role of drug-induced sleep endoscopy in the non-positive airway pressure management of obstructive sleep apnea.

Assessment of Screening for Nasal Obstruction among Sleep Dentistry Outpatients with Obstructive Sleep Apnea

Oral appliances (OA), a common treatment modality for obstructive sleep apnea (OSA), are not suitable for patients with nasal obstruction. Rhinomanometry, the gold standard technique to assess nasal airway resistance, is not readily available in sleep dentistry clinics. We demonstrate the use of a portable lightweight peak nasal inspiratory flow (PNIF) rate meter to objectively assess nasal airflow and utilized the Nasal Obstruction Symptom Evaluation (NOSE) scale to subjectively assess nasal obstruction in 97 patients with OSA and 105 healthy controls. We examined the correlations between the following variables between the groups: demographics, body mass index, PNIF, NOSE scale scores, apnea-hypopnea index (AHI), minimum SpO₂ (SpO₂min), Mallampati classification, and Epworth Sleepiness Scale (ESS) scores. Patients with OSA had significantly lower PNIF values and higher NOSE scores than controls. In the patient group, PNIF was not significantly correlated with AHI, SpO₂min, Mallampati classification, or NOSE or ESS scores. Lower PNIF values and higher NOSE scores suggested impaired nasal airflow in the OSA group. As daytime PNIF measurement bears no relationship to AHI, this cannot be used alone in predicting the suitability of treatment for OSA with OA but can be used as an adjunct for making clinical decisions.

Physiological Responses of a Jaw-Repositioning Custom-Made Mouthguard on Airway and Their Effects on Athletic Performance

Martins, RS, Girouard, P, Elliott, E, and Mekary, S. Physiological responses of a jaw repositioning custom-made mouthguard on airway and their effects on athletic performance. J Strength Cond Res 34(2): 422-429, 2020-Advanced dental techniques such as jaw-repositioning have shown to increase lower body muscular power such as vertical jump, but its effects on acceleration and speed have not been studied. Similarly, jaw repositioning is commonly used to increase airways volume and ventilation in a special population (i.e., obstructive sleep apnea); however, its ergogenic effects on aerobic performance have yet not been studied. The purpose of the cross-over study was to investigate the effects of a jaw-repositioning custom-made mouthguard (JCM) on volumetric changes in airway and jaw position and determine the effects this may have on aerobic and anaerobic performance. Results indicated that jaw-repositioning custom-made mouthguard may have an ergogenic effect on performance. The JCM condition showed an increase of 13% in upper airway volume (p = 0.04), 10% in upper airway width (p = 0.004), 7% in ventilation (p = 0.006), 5% in maximal aerobic power (p = 0.003), 4% in time to exhaustion (p = 0.03), 3% in vertical jump (p = 0.03), 2% in broad jump (p = 0.009), and a decrease of 4% in 20-m (p = 0.04) and 2% in 40-m (p = 0.001) sprint times. This is the first study to demonstrate a significant link between jaw repositioning, airway volumetric change, and performance enhancement in both aerobic and anaerobic performances. The results of this study may lead to a change in culture for the use of mouthguards in different sports applications, from high orofacial injury risk sports to other sports, specifically for ergogenic enhancement.

Identifying the Predominant Site of Upper Airway Collapse in Obstructive Sleep Apnoea Patients Using Snore Signals

Knowledge regarding the site of airway collapse could help in choosing an appropriate structure-specific or individualized treatment for obstructive sleep apnoea (OSA). We investigated if the audio signal recorded during hypopnoea (partial obstruction) events can predict the site-of-collapse of the upper airway. In this study, we designed an automatic classifier that predicts the predominant site of upper airway collapse for a patient as "lateral wall", "palate", "tongue-based" related collapse or "multi-level" site-of-collapse by processing of the audio signal. The probable site-of-collapse was determined by manual analysis of the shape of the airflow signal during hypopnoea, which has been reported to correlate with the site of collapse. Audio signal was recorded simultaneously with full-night polysomnography during sleep with a ceiling microphone. Various time and frequency features of the audio signal were extracted to classify the audio signal into lateral wall, palate and tongue-base related collapse. We introduced an unbiased process using nested leave-one patient-out cross-validation to choose the optimal features. The classification was carried out with a multi-class linear discriminant analysis classifier. Performance of the proposed model showed that our automatic system can achieve an overall accuracy of 65% for determining the predominant site-of-collapse for all site-of-collapse classes and an accuracy of 80% for classifying tongue/non-tongue related collapse. Our results indicate that the audio signal recorded during sleep can be helpful in identifying the site-of-collapse and therefore could potentially be used as a new tool for deciding appropriate treatment for OSA.

Characterisation of Upper Airway Collapse in OSA Patients Using Snore Signals: A Cluster Analysis Approach

This paper provides the results of an unsupervised learning algorithm that characterize upper airway collapse in obstructive sleep apnoea (OSA) patients using snore signal during hypopnoea events. Knowledge regarding the site-of-collapse could improve the ability in choosing the most appropriate treatment for OSA and thereby improving the treatment outcome. In this study, we implemented an unsupervised k-means clustering algorithm to label the snore data during hypopnoea events. Audio data during sleep were recorded simultaneously with full-night polysomnography with a ceiling microphone. Various time and frequency features of audio signal during hypopnoea were extracted. A systematic evaluation method was implemented to find the optimal feature set and the optimal number of clusters using silhouette coefficients. Using these optimal feature sets, we clustered the snore data into two. Performance of the proposed model showed that the data fit well in two clusters with a mean silhouette coefficients of 0.79. Also, the clusters achieved an overall accuracy of 62% for predicting tongue/non-tongue related collapse.

Upper airway volumetric changes of obstructive sleep apnoea patients treated with oral appliances: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnoea (OSA) is a common sleep-related breathing disorder, attributed to the collapse of the pharyngeal walls and the subsequent complete or partial upper airway obstruction. Among different treatment options for OSA, Continuous Positive Airway Pressure, and oral appliances (OAs) have been used, with various outcomes and side effects.

OBJECTIVE

The aim of this study was to summarize current knowledge in an evidence-based manner regarding the upper airway volume increase of OSA patients while treated with OAs.

SEARCH METHODS

Electronic search was conducted in Pubmed, Cochrane Library, and Scopus, up to May 2020.

SELECTION CRITERIA

Studies were selected after the application of predetermined eligibility criteria.

DATA COLLECTION AND ANALYSIS

Mean airway volume differences and the corresponding 95% confidence intervals were calculated, using the random effects model. Sensitivity, exploratory, and meta-regression analyses were also implemented.

RESULTS

Eleven studies filled the inclusion criteria and were included in the systematic review, while 10 of them were suitable for meta-analysis. In total, 291 patients were included, with mean upper airway volume increase of 1.95 cm3 (95% CI, 1.37-2.53; P < 0.001) with Mandibular Advancement Devices in place. In all studies, post-treatment Apnea Hypopnea Index (AHI) was either <10 events/hour or was reduced by more than 50% from baseline levels. A greater increase of the velopharynx volume was observed, regarding airway compartments.

CONCLUSIONS

Treatment with OAs in OSA may lead to a significant increase of the upper airway volume with a subsequent decrease of AHI. The velopharynx seems to be affected the most from OA therapy.

Oral Appliances in the Management of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a multifactorial condition, and an interdisciplinary approach to diagnosis forms the basis for effective treatment planning. Craniofacial structure and attached soft tissues and muscles play a central role in OSA. Evidence-based studies demonstrate the effectiveness of oral appliances for mandibular advancement and tongue stabilization in managing OSA, and current clinical standards of practice recommend the use of oral appliances to treat OSA when patients cannot tolerate continuous positive airway pressure (CPAP). Although effective, oral appliances are less predictable in managing OSA compared with CPAP therapy. Measures can be taken to improve predictability of oral appliance treatment.

Oral Appliances for Snoring and Obstructive Sleep Apnea

Obstructive sleep apnea is a common condition, caused primarily by narrowing of the nasal and pharyngeal airway, leading to partial or complete airway collapse during sleep. Treatment with positive airway pressure (PAP) is considered first-line therapy, due to an efficacy rate of approximately 95%, yet long-term compliance with PAP is less than 40%. The efficacy of a sleep oral appliance is lower than PAP, yet it may have similar effectiveness. A sleep oral appliance is a reasonable second-line therapy for patients who refuse or fail PAP and may be reasonable first-line therapy.

A Preliminary Study of the Automatic Classification of the Site of Airway Collapse in OSA patients Using Snoring Signals

In this study we investigated if audio signals may carry information related to the site of obstruction of the upper airway. The information regarding the site of collapse could improve obstructive sleep apnoea (OSA) treatment by allowing more individualized or structure-specific therapy. In this preliminary study, we developed an algorithm for automatically determining the site of collapse in 13 OSA patients through snoring analysis. Audio was recorded with a ceiling mounted microphone, simultaneously with full-night polysomnography during sleep. The surrogate measure of the site of airway collapse was identified by manual analysis of the nasal pressure signal. We extracted various time and frequency features of audio signal to classify the signal into "lateral wall", "palate" and "tongue base" related collapse. The classification was carried out with a Gaussian mixture model classifier. Performance of the proposed model showed that it can achieve an overall accuracy of 78.9±0.96% with specificity and PPV of (89.3±0.81%, 78±1.5%) (73.2±1.3% , 83.2±1.8%) (61.3±2.5%, 71.8±1.3%) for lateral wall, palate and tongue base related collapse respectively. Our preliminary results suggest that the audio signal may be helpful in identifying the site of obstruction and therefore maybe a useful tool for deciding appropriate therapy.

[OSA in adults: Role of the mandibular advancement device (MAD)]

Mandibular advancement devices are an alternative to continuous positive airway pressure for patients with mild or moderate obstructive sleep apnea/ hypopnea syndrome (OSA). Oral appliances advance the mandible and tongue, enlarge and stabilize the upper airways during sleep. Clinical examination is used to select candidates for oral appliances and a particular appliance for a given patient. Titration of the advancement will optimize its effectiveness by resolving subjective clinical symptoms. Polygraphic or ventilatory polysomnography controls the effectiveness of the treatment (IAH reduction, increase of oxygen saturation and improvement of the main symptoms). Clinical follow-up is required to assess longterm outcomes, side effects and treatment adherence. Oral appliances are effective in the short-term provided they achieved a 50% reduction in IAH and complete symptom resolution.

Randomized crossover study of tongue-retaining device and positive airway pressure for obstructive sleep apnea

PURPOSE

To compare the efficacy of tongue-retaining device (TRD) versus continuous positive airway pressure (CPAP) for treatment of obstructive sleep apnea (OSA).

STUDY DESIGN

Randomized crossover study.

SUBJECTS AND METHODS

Thirty-six patients with a mean age of 52.7 ± 10.6 years were enrolled. Inclusion criteria were age ≥ 18 years, apnea-hypopnea index (AHI) ≥ 5 events/h, and minimum oxygen saturation (SO₂) ≥ 70% from polysomnography (PSG). Exclusion criteria were severe periodontal disease, unstable cardiopulmonary or neurological diseases, and/or total sleep time < 2 h. A 1-week wash-in period was followed by questionnaires and randomization into two groups: TRD/CPAP and CPAP/TRD (18 patients each). After 3 weeks of intervention, questionnaires were re-administered and WatchPAT was performed. After a 1-week wash-out period, patients were switched to the other treatment. Primary outcome was AHI. Secondary outcomes were SO₂, Functional Outcomes of Sleep Questionnaire (FOSQ), and Epworth Sleepiness Scale (ESS) scores, treatment side effects, and adherence.

RESULTS

Nine patients withdrew, so 27 patients were included in the final analysis. Mean AHI decreased from 38.7 ± 24.0 to 2.5 ± 0.5 and 12.7 ± 2.6 events/h for CPAP and TRD, respectively (95% confidence interval of mean differences 4.65-15.62; p < 0.001). There was no significant difference in ESS and FOSQ scores between treatments. Common adverse effects were drooling, tongue numbness, and pain for TRD; and nasal blockage, mask compression, and difficult portability for CPAP.

CONCLUSIONS

CPAP was superior to TRD for resolving PSG parameters; however, both similarly improved QOL and daytime sleepiness. TRD might be considered a short-term alternative treatment for OSA.

TRIAL REGISTRATION

NCT02788487.

More Than the Sum of the Respiratory Events: Personalized Medicine Approaches for Obstructive Sleep Apnea

Traditionally, the presence and severity of obstructive sleep apnea (OSA) have been defined by the apnea-hypopnea index (AHI). Continuous positive airway pressure is generally first-line therapy despite low adherence, because it reliably reduces the AHI when used, and the response to other therapies is variable. However, there is growing appreciation that the underlying etiology (i.e., endotype) and clinical manifestation (i.e., phenotype) of OSA in an individual are not well described by the AHI. We define and review the important progress made in understanding and measuring physiological mechanisms (or endotypes) that help define subtypes of OSA and identify the potential use of genetics to further refine disease classification. This more detailed understanding of OSA pathogenesis should influence clinical treatment decisions as well as help inform research priorities and clinical study design. In short, treatments could be individualized on the basis of the underlying cause of OSA; patients could better understand which symptoms and outcomes will respond to OSA treatment and by how much; and researchers could select populations most likely to benefit from specific treatment approaches for OSA.

State-dependent changes in the upper airway assessed by multidetector CT in healthy individuals and during obstructive events in patients with sleep apnea

Objective:

To determine whether airway narrowing during obstructive events occurs predominantly at the retropalatal level and results from dynamic changes in the lateral pharyngeal walls and in tongue position.

Methods:

We evaluated 11 patients with severe obstructive sleep apnea (OSA) and 7 healthy controls without OSA during wakefulness and during natural sleep (documented by full polysomnography). Using fast multidetector CT, we obtained images of the upper airway in the waking and sleep states.

Results:

Upper airway narrowing during sleep was significantly greater at the retropalatal level than at the retroglossal level in the OSA group (p < 0.001) and in the control group (p < 0.05). The retropalatal airway volume was smaller in the OSA group than in the control group during wakefulness (p < 0.05) and decreased significantly from wakefulness to sleep only among the OSA group subjects. Retropalatal pharyngeal narrowing was attributed to reductions in the anteroposterior diameter (p = 0.001) and lateral diameter (p = 0.006), which correlated with an increase in lateral pharyngeal wall volume (p = 0.001) and posterior displacement of the tongue (p = 0.001), respectively. Retroglossal pharyngeal narrowing during sleep did not occur in the OSA group subjects.

Conclusions:

In patients with OSA, upper airway narrowing during sleep occurs predominantly at the retropalatal level, affecting the anteroposterior and lateral dimensions, being associated with lateral pharyngeal wall enlargement and posterior tongue displacement.

Oral Appliances in the Management of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a multifactorial condition, and an interdisciplinary approach to diagnosis forms the basis for effective treatment planning. Craniofacial structure and attached soft tissues and muscles play a central role in OSA. Evidence-based studies demonstrate the effectiveness of oral appliances for mandibular advancement and tongue stabilization in managing OSA, and current clinical standards of practice recommend the use of oral appliances to treat OSA when patients cannot tolerate continuous positive airway pressure (CPAP). Although effective, oral appliances are less predictable in managing OSA compared with CPAP therapy. Measures can be taken to improve predictability of oral appliance treatment.

Tongue Function: An Underrecognized Component in the Treatment of Obstructive Sleep Apnea with Mandibular Repositioning Appliance

Obstructive sleep apnea (OSA) is a common but still underrecognized disorder. A mandibular repositioning appliance (MRA) is used to treat OSA by advancing the mandible and thereby reducing the collapsibility of the upper airway. It has been found that an MRA increases the volume of the upper airway, especially the velopharyngeal area, in OSA patients. We hypothesize that this increase in the velopharyngeal volume is associated with an anterior displacement of the tongue, but likely not with a stretching of the soft tissue connecting the soft palate, lateral pharynx, palatopharyngeal arch, and mandible. Since the function and structure of the genioglossus and hypoglossal nerve are always abnormal in patients with OSA, the tongue does not always move simultaneously with the mandible when an MRA is being used. Oropharyngeal exercises, especially tongue exercises, can improve the quality of life of OSA patients, including reduction of daytime sleepiness and snoring, better quality of sleep, and partial decrease in the AHI. Further, in animal models, tongue exercise is also found to be effective in tongue function recovery and in the remodeling of the hypoglossal nucleus. We suggest that a combination of tongue exercises along with MRA is a promising approach for patients who do not respond to an MRA alone.

Magnetic resonance imaging of the upper airway in patients with quadriplegia and obstructive sleep apnea

The aim of this study was to investigate upper airway anatomy in quadriplegics with obstructive sleep apnea. Fifty subjects were recruited from three hospitals in Australia: people with quadriplegia due to spinal cord injury and obstructive sleep apnea (n = 11), able-bodied people with obstructive sleep apnea (n = 18), and healthy, able-bodied controls (n = 19). All underwent 3-Tesla magnetic resonance imaging of their upper airway. A subgroup (n = 34) received a topical vasoconstrictor, phenylephrine and post-phenylephrine magnetic resonance imaging. Mixed-model analysis indicated no significant differences in total airway lumen volume between the three groups (P = 0.086). Spinal cord injury-obstructive sleep apnea subjects had a significantly larger volume of soft palate (P = 0.020) and retroglossal lateral pharyngeal walls (P = 0.043) than able-bodied controls. Able-bodied-obstructive sleep apnea subjects had a smaller mandible volume than spinal cord injury-obstructive sleep apnea subjects and able-bodied control subjects (P = 0.036). No differences were seen in airway length between groups when controlling for height (P = 0.055). There was a marginal increase in velopharyngeal volume across groups post-phenylephrine (P = 0.050), and post hoc testing indicated the difference was confined to the able-bodied-obstructive sleep apnea group (P < 0.001). No other upper airway structures showed significant changes with phenylephrine administration. In conclusion, people with obstructive sleep apnea and quadriplegia do not have a structurally smaller airway than able-bodied subjects. They did, however, have greater volumes of soft palate and lateral pharyngeal walls, possibly due to greater neck fat deposition. The acute response to upper airway topical vasoconstriction was not enhanced in those with obstructive sleep apnea and quadriplegia. Changes in upper airway anatomy likely contribute to the high incidence in obstructive sleep apnea in quadriplegic subjects.

Oral Appliances for the Management of OSA: An Updated Review of the Literature

Oral appliances (OAs) are becoming increasingly recognized not only as an alternative to but also possibly as an adjunct treatment modality for OSA. Compared with CPAP, the gold standard therapy, OAs are less efficacious but are more accepted and tolerated by patients, which, in turn, may lead to a comparable level of therapeutic effectiveness. Different OA designs currently exist, and more are constantly emerging. Additionally, state-of-the-art technologies are being used in the fabrication of many; however, all the currently available OAs employ the same mechanism of action by targeting the anatomical component involved in the pathogenesis of the disease. Furthermore, the scope of use of OAs is expanding to include patients who are edentulous. For patients with OAs, the dentist is a member of an interdisciplinary team managing OSA, and constant communication and follow-up with the sleep physician and other team members is necessary for disease management.

A novel imaging technique to evaluate airflow characteristics in the upper airway of an obstructive sleep apnea patient

We report about a novel imaging technique for airflow analysis, particle image velocimetry (PIV), used in a moderate obstructive sleep apnea (OSA) patient. By measuring the airflow characteristics in the upper airway at different protrusion positions, the effect of mandibular advancement device (MAD) on OSA was further understood.

Tongue retaining devices for obstructive sleep apnea: A systematic review and meta-analysis

OBJECTIVE

Tongue Retaining Devices (TRD) anteriorly displace the tongue with suction forces while patients sleep. TRD provide a non-surgical treatment option for patients with Obstructive Sleep Apnea (OSA). Our objective was to conduct a systematic review of the international literature for TRD outcomes as treatment for OSA.

METHODS

Three authors independently and systematically searched four databases (including PubMed/MEDLINE) through June 26, 2016. We followed guidelines set within the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

Sixteen studies with 242 patients met criteria. The overall means±standard deviations (M±SD) for apnea-hypopnea index (AHI) decreased from 33.6±21.1/h to 15.8±16.0/h (53% reduction). Seven studies (81 patients) reported lowest oxygen saturation (LSAT), which improved from 79.8±17.5% to 83.9±8.6%. Four studies (93 patients) reported Epworth sleepiness scale (ESS), which decreased from 10.8±4.8 to 8.2±4.5, p <0.0001. Four studies (31 patients) reported Oxygen Desaturation Index (ODI) which decreased from 29.6±32.1 to 12.9±8.7, a 56.4% reduction.

CONCLUSION

Current international literature demonstrates that tongue retaining devices reduce apnea-hypopnea index by 53%, increase lowest oxygen saturation by 4.1 oxygen saturation points, decrease oxygen desaturation index by 56% and decrease Epworth sleepiness scale scores by 2.8 points. Tongue retaining devices provide a statistically effective alternative treatment option for obstructive sleep apnea.

Upper-Airway Collapsibility and Loop Gain Predict the Response to Oral Appliance Therapy in Patients with Obstructive Sleep Apnea

RATIONALE

Oral appliances (OAs) are commonly used as an alternative treatment to continuous positive airway pressure for patients with obstructive sleep apnea (OSA). However, OAs have variable success at reducing the apnea-hypopnea index (AHI), and predicting responders is challenging. Understanding this variability may lie with the recognition that OSA is a multifactorial disorder and that OAs may affect more than just upper-airway anatomy/collapsibility.

OBJECTIVES

The objectives of this study were to determine how OA alters AHI and four phenotypic traits (upper-airway anatomy/collapsibility and muscle function, loop gain, and arousal threshold), and baseline predictors of which patients gain the greatest benefit from therapy.

METHODS

In a randomized crossover study, 14 patients with OSA attended two sleep studies with and without their OA. Under each condition, AHI and the phenotypic traits were assessed. Multiple linear regression was used to determine independent predictors of the reduction in AHI.

MEASUREMENTS AND MAIN RESULTS

OA therapy reduced the AHI (30 ± 5 vs. 11 ± 2 events/h; P < 0.05), which was driven by improvements in upper-airway anatomy/collapsibility under passive (1.9 ± 0.7 vs. 4.7 ± 0.6 L/min; P < 0.005) and active conditions (2.4 ± 0.9 vs. 6.2 ± 0.4 L/min; P < 0.001). No changes were seen in muscle function, loop gain, or the arousal threshold. Using multivariate analysis, baseline passive upper-airway collapsibility and loop gain were independent predictors of the reduction in AHI (r2 = 0.70; P = 0.001).

CONCLUSIONS

Our findings suggest that OA therapy improves the upper-airway collapsibility under passive and active conditions. Importantly, a greater response to therapy occurred in those patients with a mild anatomic compromise and a lower loop gain.

Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) has a high prevalence and carries significant cardiovascular risks. It is important to study new therapeutic approaches to this disease. Positional therapy might be beneficial in reducing the apnea-hypopnea index (AHI). Imaging methods have been employed in order to facilitate the evaluation of the airways of OSAS patients and can be used in order to determine the effectiveness of certain treatments. This study was aimed at determining the influence that upper airway volume, as measured by cervical CT, has in patients diagnosed with OSAS.

METHODS

This was a quantitative, observational, cross-sectional study. We evaluated 10 patients who had been diagnosed with OSAS by polysomnography and on the basis of the clinical evaluation. All of the patients underwent conventional cervical CT in the supine position. Scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination), and the upper airway volume was compared between the two.

RESULTS

The mean age, BMI, and neck circumference were 48.9 ± 14.4 years, 30.5 ± 3.5 kg/m2, and 40.3 ± 3.4 cm, respectively. The mean AHI was 13.7 ± 10.6 events/h (range, 6.0-41.6 events/h). The OSAS was classified as mild, moderate, and severe in 70%, 20%, and 10% of the patients, respectively. The mean upper airway volume was 7.9 cm3 greater when the head was at a 44° upward inclination than when it was in the neutral position, and that difference (17.5 ± 11.0%) was statistically significant (p = 0.002).

CONCLUSIONS

Elevating the head appears to result in a significant increase in the caliber of the upper airways in OSAS patients.

The size and behavior of the human upper airway during inhalation of aerosols

INTRODUCTION

The mouth, the pharynx and the larynx are potential sites of aerosol deposition in the upper airway during inhalation of aerosolized drugs. The right angle bend of the lumen at the back of the mouth, the position of the tongue, the variable size and shape of the lumen in the pharynx and the larynx, and the breathing pattern could increase aerosol deposition in the upper airway and decrease lung deposition. Areas covered: In this review, the anatomy of the upper airway from the oral cavity to the glottis and the impact of mandibular protrusion and incisal opening on the size of the upper airway are highlighted. In addition, the impact of inhalation maneuvers, inhaler mouthpiece geometries and a stepped mouthpiece on the size of the upper airway are discussed. Expert opinion: The structure of the upper airway lumen does not have a fixed cross sectional area and is susceptible to both constriction and distension during inhalation. The size of the upper airway can be enlarged through mandibular protrusion and/or incisal opening which might decrease aerosol deposition in the upper airway and increase lung deposition.

Can treatment with statins have a negative influence on the tolerance of mandibular advancement devices?

BACKGROUND

Statins are considered the most effective drugs used in the treatment of dyslipidemias. Some of their adverse effects are related to muscle problems. Myalgias produced by statins appear more often during exercise. Mandibular advancement devices (MAD) force the propulsory and elevatory musculature of the mandible to exercise by making the jaw move forward. The aim of this study is to evaluate the incidence of muscular side effects (referred, spontaneous, or under palpation pain, myofascial pain, mandibular rigidity and fatigue, tension and sensitivity of the masticatory muscles) in a group of patients with a diagnosis of obstructive sleep apnea being treated with MAD.

METHODS

This was a prospective study, involving consecutively 104 patients with a diagnosis of OSAS, and who had begun treatment with a custom made oral device. Muscular side effects were collected by anamnesis (verbal request and questionnaires), psychological status and clinical assessment (manual muscle palpation in the masticatory and cervical muscle groups), before and during MAD treatment.

RESULTS

Of the total sample, 22.1 % presented muscular side effects with the oral device. However, in patients taking statins, this percentage was 57.1 %, as opposed to 16.7 % of the non-statins patients (p < 0.001). The risk of suffering muscular alterations during oral device treatment is higher in statin patients (odds ratio 6.67, p = 0.002).

CONCLUSION

Treatment with statins can give rise to the appearance of undesirable side effects among patients being treated with oral devices.

Supra-Epiglottic Upper Airway Volume in Elderly Patients with Obstructive Sleep Apnea Hypopnea Syndrome

Objective

Small upper airway measurements areas and high body mass index are recognized risk factors for obstructive sleep apnea syndrome (OSAS) in non-elderly populations; however, there is limited information regarding elderly patients. We evaluated whether upper airway volume is associated with OSAS and OSAS treated with continuous positive airway pressure (CPAP) treatment and whether BMI is correlated with upper airway volume and measurements in elderly subjects.

Methods

In 60 volunteers aged 75.58±0.9 years: 20 OSAS, 20 OSAS chronically treated with CPAP, and 20 controls, semi-automatic segmentation, retropalatal distance and transverse diameter of the supra-epiglottic upper airway were evaluated using 3DT1-weighted magnetic resonance imaging. Anteroposterior to transverse diameter ratio was defined as retropalatar diameter/transverse diameter.

Results

There were no significant differences in supra-epiglottic upper airway volume between OSAS, CPAP treated patients, and controls. There were significant differences in retropalatal distance and anteroposterior to transverse diameter ratio between OSAS, CPAP treated patients, and controls (P = 0.008 and P<0.0001 respectively). There was a significant correlation between body mass index and retropalatal distance (P<0.05) but not with supra-epiglottic upper airway volume.

Conclusion

In elderly subjects, OSAS and body mass index are not associated with changes in supra-epiglottic upper airway volume but are associated with modification of pharynx shape.

Development and validation of a computational finite element model of the rabbit upper airway: simulations of mandibular advancement and tracheal displacement

The mechanisms leading to upper airway (UA) collapse during sleep are complex and poorly understood. We previously developed an anesthetized rabbit model for studying UA physiology. On the basis of this body of physiological data, we aimed to develop and validate a two-dimensional (2D) computational finite element model (FEM) of the passive rabbit UA and peripharyngeal tissues. Model geometry was reconstructed from a midsagittal computed tomographic image of a representative New Zealand White rabbit, which included major soft (tongue, soft palate, constrictor muscles), cartilaginous (epiglottis, thyroid cartilage), and bony pharyngeal tissues (mandible, hard palate, hyoid bone). Other UA muscles were modeled as linear elastic connections. Initial boundary and contact definitions were defined from anatomy and material properties derived from the literature. Model parameters were optimized to physiological data sets associated with mandibular advancement (MA) and caudal tracheal displacement (TD), including hyoid displacement, which featured with both applied loads. The model was then validated against independent data sets involving combined MA and TD. Model outputs included UA lumen geometry, peripharyngeal tissue displacement, and stress and strain distributions. Simulated MA and TD resulted in UA enlargement and nonuniform increases in tissue displacement, and stress and strain. Model predictions closely agreed with experimental data for individually applied MA, TD, and their combination. We have developed and validated an FEM of the rabbit UA that predicts UA geometry and peripharyngeal tissue mechanical changes associated with interventions known to improve UA patency. The model has the potential to advance our understanding of UA physiology and peripharyngeal tissue mechanics.

Clinical Practice Guideline for the Treatment of Obstructive Sleep Apnea and Snoring with Oral Appliance Therapy: An Update for 2015

INTRODUCTION

Since the previous parameter and review paper publication on oral appliances (OAs) in 2006, the relevant scientific literature has grown considerably, particularly in relation to clinical outcomes. The purpose of this new guideline is to replace the previous and update recommendations for the use of OAs in the treatment of obstructive sleep apnea (OSA) and snoring.

METHODS

The American Academy of Sleep Medicine (AASM) and American Academy of Dental Sleep Medicine (AADSM) commissioned a seven-member task force. A systematic review of the literature was performed and a modified Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the quality of evidence. The task force developed recommendations and assigned strengths based on the quality of the evidence counterbalanced by an assessment of the relative benefit of the treatment versus the potential harms. The AASM and AADSM Board of Directors approved the final guideline recommendations.

RECOMMENDATIONS

1. We recommend that sleep physicians prescribe oral appliances, rather than no therapy, for adult patients who request treatment of primary snoring (without obstructive sleep apnea). (STANDARD) 2. When oral appliance therapy is prescribed by a sleep physician for an adult patient with obstructive sleep apnea, we suggest that a qualified dentist use a custom, titratable appliance over non-custom oral devices. (GUIDELINE) 3. We recommend that sleep physicians consider prescription of oral appliances, rather than no treatment, for adult patients with obstructive sleep apnea who are intolerant of CPAP therapy or prefer alternate therapy. (STANDARD) 4. We suggest that qualified dentists provide oversight—rather than no follow-up—of oral appliance therapy in adult patients with obstructive sleep apnea, to survey for dental-related side effects or occlusal changes and reduce their incidence. (GUIDELINE) 5. We suggest that sleep physicians conduct follow-up sleep testing to improve or confirm treatment efficacy, rather than conduct follow-up without sleep testing, for patients fitted with oral appliances. (GUIDELINE) 6. We suggest that sleep physicians and qualified dentists instruct adult patients treated with oral appliances for obstructive sleep apnea to return for periodic office visits—as opposed to no follow-up—with a qualified dentist and a sleep physician. (GUIDELINE).

CONCLUSIONS

The AASM and AADSM expect these guidelines to have a positive impact on professional behavior, patient outcomes, and, possibly, health care costs. This guideline reflects the state of knowledge at the time of publication and will require updates if new evidence warrants significant changes to the current recommendations.

Three-dimensional computed tomography analysis of airway volume changes between open and closed jaw positions

INTRODUCTION

Airway dimensions are closely linked to the bone and soft-tissue craniofacial anatomy. Reduction of the airway is seen with airway disorders and can impair function. The purpose of this retrospective study was to determine whether changing from open to closed jaw position affects the volume of the nasal cavity, nasopharynx, and oropharynx; the soft palate; the soft-tissue thickness of the airway; and the most constricted area of the airway.

METHODS

Following reliability studies, in this retrospective study, we analyzed cone-beam computed tomography scans taken in both closed and open jaw positions of 60 subjects who were undergoing diagnosis and treatment of temporomandibular disorders. On each scan, condyle-fossa measurements, volumes of airway segments (nasal cavity, nasopharynx, oropharynx), soft palate areas, soft tissue thicknesses of the airway, and the most constricted area of the airway and its location were measured using Dolphin imaging software (version 11.5; Patterson Dental Supply, Chatsworth, Calif). Differences between the 2 jaw positions were analyzed with paired t tests, accepting P ≤0.05 as significant.

RESULTS

Significant changes in airway dimensions were found between the closed and open jaw positions. With jaw opening, the nasopharynx volume increased, whereas the oropharynx volume decreased. Significant decreases were also found for measurements of basion to posterior airway wall, cervical vertebrae to posterior airway wall, most constricted area, nasal cavity volume, and soft palate area when the jaw was open.

CONCLUSIONS

Changing jaw position significantly affects airway dimensions.

The status of cephalometry in the prediction of non-CPAP treatment outcome in obstructive sleep apnea patients

Obstructive sleep apnea syndrome (OSAS) is the most common sleep disordered breathing disorder (SDB) in adults and is characterized by a recurrent partial or complete collapse of the upper airway during sleep. This can be caused by many factors, sometimes interacting, such as skeletal malformations, soft tissue crowding, respiratory instability and the various effects of aging, obesity and gender that dictate craniofacial and upper airway anatomy. Research has demonstrated that the majority of patients exhibit at least one anatomical component such as retrognathia or a narrow posterior airway space that predisposes to the development of OSAS. Within the predisposing elements for OSAS many seem to point to anatomical characteristics. A standardized and relatively simple radiologic technique to evaluate anatomical craniofacial relationships is cephalometry. This has been used already for a long time in orthodontics, but is now gradually being introduced in OSAS treatment to envisage optimal treatment selection as well as to predict treatment outcomes. The purpose of the present review is to evaluate the contribution of cephalometry in the prediction of outcomes from OSAS treatments that depend on the upper airway morphology in their mechanisms of action such as oral appliances that advance the mandible as well as various surgical methods. In addition, an overview of imaging modalities and methods that currently are being used in cephalometric analysis in OSAS patients is provided. The findings indicate that isolated cephalometric parameters cannot be used to reliably predict treatment outcomes from mandibular advancement devices and surgical methods for OSAS. Extreme or outlying values of cephalometric parameters may rather be used as contra-indicators or 'red flags' instead of predictors.

Peripharyngeal tissue deformation, stress distributions, and hyoid bone movement in response to mandibular advancement

Mandibular advancement (MA) increases upper airway (UA) patency and decreases collapsibility. Furthermore, MA displaces the hyoid bone in a cranial-anterior direction, which may contribute to MA-associated UA improvements via redistribution of peripharyngeal tissue stresses (extraluminal tissue pressure, ETP). In the present study, we examined effects of MA on ETP distributions, deformation of the peripharyngeal tissue surface (UA geometry), and hyoid bone position. We studied 13 supine, anesthetized, tracheostomized, spontaneously breathing adult male New Zealand White rabbits. Graded MA was applied from 0 to ∼4.5 mm. ETP was measured at six locations distributed throughout three UA regions: tongue, hyoid, and epiglottis. Axial computed tomography images of the UA (nasal choanae to glottis) were acquired and used to measure lumen geometry (UA length; regional cross-sectional area) and hyoid displacement. MA resulted in nonuniform decreases in ETP (greatest at tongue region), ranging from −0.11 (−0.15 to −0.06) to −0.82 (−1.09 to −0.54) cmH2O/mm MA [linear mixed-effects model slope (95% confidence interval)], across all sites. UA length decreased by −0.5 (−0.8 to −0.2) %/mm accompanied by nonuniform increases in cross-sectional area (greatest at hyoid region) ranging from 7.5 (3.6–11.4) to 18.7 (14.9–22.5) %/mm. The hyoid bone was displaced in a cranial-anterior direction by 0.42 (0.36–0.44) mm/mm MA. In summary, MA results in nonuniform changes in peripharyngeal tissue pressure distributions and lumen geometry. Displacement of the hyoid bone with MA may play a pivotal role in redistributing applied MA loads, thus modifying tissue stress/deformation distributions and determining resultant UA geometry outcomes.