Effect of a non-adjustable oral appliance on upper airway morphology in obstructive sleep apnoea

Comparison of Pre- and Posttreatment Airway Volume in Patients with Temporomandibular Joint Disorders Treated with Ultra-Low Frequency Transcutaneous Electrical Nerve Stimulation Using Cone Beam Computed Tomography

Introduction  Temporomandibular joint disorders (TMD) present with a multitude of symptoms that can range from headaches to shoulder pain. Patients frequently present with pain in the ear, dizziness, and vertigo. It is noted that some patients who report TMDs also have a history of sleep disturbances, which is noted in cone beam computed tomography (CBCT) as a reduction in the oropharyngeal airway volume. Objective  To evaluate the airway volume in pre- and posttreatment of TMD with the use of neuromuscular orthotics made with ultra-low frequency transcutaneous electrical nerve stimulation (ULF-TENS). Methods  A total of 15 patients were evaluated for TMDs using the related criteria. Those included were treated with ULF-TENS with evaluation of the airway volume both pre- and posttreatment using CBCT and the Dolphin 3D volume analysis software. Results  While the symptoms were shown to be significantly reduced in patients who were treated with this particular modality, the airway volume varied in those who reported a reduction after a period of 3 months and those that reported after a period of 6 months. Conclusion  Posttreatment evaluation of the airway should be done after a period of 6 months for a more objective evaluation. A multidisciplinary evaluation of the patient is required in such cases.

Dental Appliances for the Treatment of Obstructive Sleep Apnea in Children: A Systematic Review and Meta-Analysis

Background and objectives: Obstructive sleep apnea (OSA) in children is a debilitating disease, difficult to treat. Dental appliances have been proposed as a valid therapy for improving functional outcomes with good compliance rates. Herein, we aimed to perform a meta-analysis comparing clinical outcomes between OSA children treated with dental appliances versus controls. Materials Methods: The study was registered with PROSPERO. A systematic search was performed for all comparative studies examining outcomes in pediatric patients who underwent treatment of OSA with oral appliances versus controls. Data was extracted and analyzed using a random effects model via Rev Man 5.3. Results: Six studies including 180 patients were analyzed split into two groups: patients treated with dental appliances (n = 123) and the controls (n = 119). Therapy with dental appliances was shown to significantly improve the apnea-hypopnea index (p = 0.009) and enlarge the superior posterior airway space (p = 0.02). Maxilla-to-mandible measurements were not significantly different between the two groups, nor was the mean SO2 (p = 0.80). Conclusions: This is the most updated meta-analysis assessing the role of dental appliances for OSA in children; it shows that such devices can improve functional outcomes by decreasing the apnea-hypopnea index.

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.

Computational fluid dynamics simulation of changes in the morphology and airflow dynamics of the upper airways in OSAHS patients after treatment with oral appliances

OBJECTIVES

To explore the changes of morphology and internal airflow in upper airways (UA) after the use of oral appliances (OAs) in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), and investigate the mechanisms by which OAs function as a therapy for OSAHS.

METHODS

Eight OSAHS patients (all male, aged 37-58, mean age 46.25) underwent CT scans before and after OA use. Then, computational fluid dynamics(CFD) models were built on the base of the CT scans using Mimics and ANSYS ICEM CFD software. The internal airflow of the upper airways was simulated using ANSYS-FLUENT and the results were analyzed using ANSYS-CFD-Post. The data were analyzed to identify the most important changes of biomechanical properties between patients with and without OA intervention. Upper airway morphology and the internal airflow changes were compared using t-tests and Spearman correlation coefficient analysis.

RESULTS

The narrowest area of upper airways was found to be located in the lower bound of velopharynx, where the volume and pressure were statistically significantly increased (P<0.05) and the air velocity was statistically significantly decreased (P<0.05) in the presence of the OA(P<0.05). After wearing OA, pharyngeal resistance was significantly decreased (P<0.05), from 290.63 to 186.25Pa/L, and the airflow resistance of the pharynx has reduced by 35.9%.

CONCLUSION

The enlargement of the upper airway after wearing the OA changed its airflow dynamics, which decreased the negative pressure and resistance in narrow areas of the upper airways. Thus, the collapsibility of the upper airways was reduced and patency was sustained.

Mandibular advancement reveals long-term suppression of breathing discomfort in patients with obstructive sleep apnea syndrome

Obstructive sleep apnoea syndrome (OSAS) patients do not report breathing discomfort in spite of abnormal upper airway mechanics. We studied respiratory sensations in OSAS patients without and with mandibular advancement device (MAD). Fifty-seven moderate to severe non obese OSAS patients were asked about breathing discomfort using visual analogue scales (VAS) in the sitting position (VAS-1), after lying down (VAS-2), then with MAD (VAS-3). Awake critical closing pressure (awake Pcrit) was measured in 15 patients without then with MAD. None of the patients reported breathing discomfort when sitting but 19 patients (33%) did when lying (VAS-2: -20% or less). A feeling of "easier breathing" with MAD was observed and was more marked in patients reporting breathing discomfort when supine (VAS-3: +66.0% [49.0; 89.0]) than in those not doing so (VAS-3: +28.5% [1.0; 56.5], p = 0.007). MAD-induced change in awake Pcrit was correlated to VAS-3. In conclusion, MAD revealed "latent dyspnea" related to the severity of upper airways mechanics abnormalities in OSAS patients.

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.

Tratamiento con dispositivos orales para síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

El objetivo de este artículo es mejorar la práctica con dispositivos orales (DO) por parte del odontólogo tratante, al alcanzar una adecuada selección del DO y brindar seguridad y efectividad al paciente. Con el uso de estos, se intenta disminuir la frecuencia o duración de los eventos respiratorios. Los DO están indicados en pacientes con ronquido primario, síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) leve-moderado y SAHOS severo que no quieran o no toleren tratamiento con presión positiva. Además, se clasifican en aparatos de retención de lengua, aparatos no ajustables y ajustables, siendo estos últimos los más recomendados por ser dispositivos de avance mandibular (DAM), pues son hechos a la medida, ajustables y de arco dual. Su mecanismo de acción consiste en protruisión del maxilar inferior, adelantamiento del hueso hioides y apertura mandibular.Los DAM son más eficaces en pacientes jóvenes, con menor índice de masa corporal (IMC), circunferencia de cuello reducida, SAHOS posicional y mandíbula retrognática. Se pueden presentar efectos adversos como salivación excesiva, cambios oclusales y trastornos temporomandibulares. Se ha demostrado que los DAM tienen un impacto en la disminución del índice de apnea-hipopnea (IAH) y somnolencia diurna, mejoría en la oxigenación nocturna, función cardiovascular, calidad de vida y comportamiento neurocognitivo. Asimismo, los DAM son superiores al tratamiento con presión positiva de vía aérea (PAP) en adherencia. Se sugiere que la terapia combinada de DAM con PAP y otros tratamientos es promisoria para aquellos pacientes que responden de manera insuficiente a la monoterapia.

A pilot study for segmentation of pharyngeal and sino-nasal airway subregions by automatic contour initialization

PURPOSE

The objective of the present study is to put forward a novel automatic segmentation algorithm to segment pharyngeal and sino-nasal airway subregions on 3D CBCT imaging datasets.

METHODS

A fully automatic segmentation of sino-nasal and pharyngeal airway subregions was implemented in MATLAB programing environment. The novelty of the algorithm is automatic initialization of contours in upper airway subregions. The algorithm is based on boundary definitions of the human anatomy along with shape constraints with an automatic initialization of contours to develop a complete algorithm which has a potential to enhance utility at clinical level. Post-initialization; five segmentation techniques: Chan-Vese level set (CVL), localized Chan-Vese level set (LCVL), Bhattacharya distance level set (BDL), Grow Cut (GC), and Sparse Field method (SFM) were used to test the robustness of automatic initialization.

RESULTS

Precision and F-score were found to be greater than 80% for all the regions with all five segmentation methods. High precision and low recall were observed with BDL and GC techniques indicating an under segmentation. Low precision and high recall values were observed with CVL and SFM methods indicating an over segmentation. A Larger F-score value was observed with SFM method for all the subregions. Minimum F-score value was observed for naso-ethmoidal and sphenoidal air sinus region, whereas a maximum F-score was observed in maxillary air sinuses region. The contour initialization was more accurate for maxillary air sinuses region in comparison with sphenoidal and naso-ethmoid regions.

CONCLUSION

The overall F-score was found to be greater than 80% for all the airway subregions using five segmentation techniques, indicating accurate contour initialization. Robustness of the algorithm needs to be further tested on severely deformed cases and on cases with different races and ethnicity for it to have global acceptance in Katradental radKatraiology workflow.

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.

Three-dimensional evaluation of upper airway in patients with obstructive sleep apnea syndrome during oral appliance therapy

Obstructive sleep apnea syndrome (OSAS) represents a frequent and common respiratory disease characterized by repeated episodes of complete and/or partial obstruction of upper airways during sleep, normally associated with reduction of oxygen saturation in blood. The oral appliances (OAs) are considered to be an effective treatment modality thanks to the upper airway enlargement. Lateral cephalometry has been used for the 2-dimensional evaluation of upper airway form with several limits. We obtained an accurate 3-dimensional (3D) volume analyses with cone beam computed tomography (CBCT) scans to confirm the effects of OA on the upper airway in patients with OSAS. Ten Italian patients with moderate or severe OSA (3 males and 7 females, 53.4 ± 11.3 years of age, and BMI 24.5 ± 2.7), who cannot tolerate continuous positive air pressure therapy and rejected a surgical approach, were treated with non-adjustable customized OAs and evaluated with CBCT and polysomnography. Upper airway form was examined in the presence and absence of OA and the volume was measured and compared in 2 different areas. Specific planes have been considered to match the data and calculate the benefit obtained with therapy. Nine out of ten patients showed an improvement of total upper airway volume and an improvement in apnea-hypopnea index. Volume increased both in the posterior soft palate region and in the posterior tongue region. In the inferior area, we observed greater differences. 3D image reconstruction accurately confirmed morphological changes in the upper airway during OA therapy. The use of this 3D evaluation is expected to improve the results of OA therapy in the future.

Cephalometric predictors of treatment outcome with mandibular advancement devices in adult patients with obstructive sleep apnea: a systematic review

Objective

The efficacy of mandibular advancement devices (MADs) in the treatment of obstructive sleep apnea (OSA) ranges between 42% and 65%. However, it is still unclear which predictive factors can be used to select suitable patients for MAD treatment. This study aimed to systematically review the literature on the predictive value of cephalometric analysis for MAD treatment outcomes in adult OSA patients.

Methods

The MEDLINE, Google Scholar, Scopus, and Cochrane Library databases were searched through December 2014. Reference lists from the retrieved publications were also examined. English language studies published in international peer-reviewed journals concerning the predictive value of cephalometric analysis for MAD treatment outcome were considered for inclusion. Two review authors independently assessed eligibility, extracted data, and ascertained the quality of the studies.

Results

Fifteen eligible studies were identified. Most of the skeletal, dental, and soft tissue cephalometric measurements examined were widely recognized as not prognostic for MAD treatment outcome; however, controversial and limited data were found on the predictive role of certain cephalometric measurements including cranial base angle, mandibular plane angle, hyoid to mandibular plane distance, posterior nasal spine to soft-palate tip distance, anterior nasal spine to epiglottis base distance, and tongue/oral cross sectional area ratio thus justifying additional studies on these parameters.

Conclusions

Currently available evidence is inadequate for identification of cephalometric parameters capable of reliably discriminating between poor and good responders to MAD treatment. To guide further research, methodological weaknesses of the currently available studies were highlighted and possible reasons for their discordant results were analyzed.

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.

Effects of varying mandibular protrusion and degrees of vertical opening on upper airway dimensions in apneic dentate subjects

INTRODUCTION

Despite numerous studies investigating the dimensional and therapeutic effects of mandibular advancement splints (MASs), data regarding the effects of differently designed individual and non-adjustable MASs on the upper airway in fully dentate apneic subjects in the sagittal plane including comparison of these effects with a placebo device are sparse. The present study aimed to determine the dimensional changes in the sagittal plane created by differently designed MASs in the upper airway in fully dentate apneic subjects and to compare these changes with the effects of a placebo device.

MATERIALS AND METHODS

Magnetic resonance (MR) images of 9 dentate apneic subjects with 5 differently designed MASs and without a MAS were obtained. We measured the area of the entire pharynx (velopharynx, oropharynx, hypopharynx) on these MR images and compared the dimensional changes.

RESULTS

The dimensional changes triggered by two specific MASs (75% of the maximum mandibular protrusion with 5 mm vertical opening, and 75% of the maximum mandibular protrusion with 10 mm of vertical opening) in the entire pharynx in the sagittal plane were statistically significant compared to the other MASs (p < 0.05). The MAS effecting 75% of the maximum mandibular protrusion and 10 mm of vertical opening created a significant dimensional increase only in the velopharyngeal area among the three pharyngeal sites (p ≤ 0.003).

CONCLUSION

While the degree of mandibular protrusion created by the MAS affects the dimensions of the upper airway, the degree of the vertical opening exerts no significant dimensional effect in the sagittal plane in fully dentate apneic patients. The mandibular protrusion effect is comparatively larger in the velopharyngeal region.

The use of a mandibular repositioning device for obstructive sleep apnea

The objective of this study was to verify the effect of a mandibular repositioning device (MRD) on polysomnographic parameters and on the mean electromyographic activity of the masseter and temporal muscles in individuals with obstructive sleep apnea syndrome (OSAS). This is a prospective cohort study conducted at multidisciplinary OSAS center in a tertiary referral center. Nineteen individuals with mild or moderate OSAS associated with Mallampati 3-4 were treated with an MRD during sleep. The subjects underwent diurnal electromyography (EM) and nocturnal polysomnography (PSG) examinations both prior and after initial treatment (3 months with MRD for PSG and 6 and 12 months of treatment for EM). The examinations performed at different times were compared. Comparison of the initial and final polysomnography examination revealed a significant mean reduction of apnea-hypopnea index (AHI) from 13.8 to 7.8. The successful treatment rate with the MRD was 52.6%, and the improved treatment rate was 68.4%. Patients with lower pre-treatment AHI presented higher rates of cure. There was no statistically significant change in electromyography examination among different times. The MRD reduced the apnea-hypopnea index in individuals with enlarged base of tongue and mild and moderate OSAS without damaging the function of the masseter and temporal muscles as determined by electromyography.

Tongue and lateral upper airway movement with mandibular advancement

STUDY OBJECTIVES

To characterize tongue and lateral upper airway movement and to image tongue deformation during mandibular advancement.

DESIGN

Dynamic imaging study of a wide range of apnea hypopnea index (AHI), body mass index (BMI) subjects.

SETTING

Not-for-profit research institute.

PARTICIPANTS

30 subjects (aged 31-69 y, AHI 0-75 events/h, BMI 17-39 kg/m(2)).

INTERVENTIONS

Subjects were imaged using dynamic tagged magnetic resonance imaging during mandibular advancement. Tissue displacements were quantified with the harmonic phase technique.

MEASUREMENTS AND RESULTS

Mean mandibular advancement was 5.6 ± 1.8 mm (mean ± standard deviation). This produced movement through a connection from the ramus of the mandible to the pharyngeal lateral walls in all subjects. In the sagittal plane, 3 patterns of posterior tongue deformation were seen with mandibular advancement-(A) en bloc anterior movement, (B) anterior movement of the oropharyngeal region, and (C) minimal anterior movement. Subjects with lower AHI were more likely to have en bloc movement (P = 0.04) than minimal movement. Antero-posterior elongation of the tongue increased with AHI (R = 0.461, P = 0.01). Mean anterior displacements of the posterior nasopharyngeal and oropharyngeal regions of the tongue were 20% ± 13% and 31% ± 17% of mandibular advancement. The posterior tongue compressed 1.1 ± 2.2 mm supero-inferiorly.

CONCLUSIONS

Mandibular advancement has two mechanisms of action which increase airway size. In subjects with low AHI, the entire tongue moves forward. Mandibular advancement also produces lateral airway expansion via a direct connection between the lateral walls and the ramus of the mandible.

CITATION

Brown EC; Cheng S; McKenzie DK; Butler JE; Gandevia SC; Bilston LE. Tongue and lateral upper airway movement with mandibular advancement. SLEEP 2013;36(3):397-404.

Effects of mandibular advancement on upper airway dimension and collapsibility in patients with obstructive sleep apnea using dynamic upper airway imaging during sleep

OBJECTIVES

The objective of this study was to evaluate the effects of mandibular advancement on oropharyngeal dimension and collapsibility and reveal the predominate site of change produced by mandibular advancement in patients with obstructive sleep apnea (OSA).

STUDY DESIGN

Sixteen adults (13 males and 3 females) with symptomatic mild to severe OSA participated. Custom-made silicone mandibular positioners were used to keep the mandible at 67% of maximum advancement. Changes in the oropharyngeal size and collapsibility with mandibular advancement were evaluated using ultrafast computed tomography taken during wakefulness and midazolam-induced sleep. Cross-sectional areas were assessed using electron beam tomography at 4 levels: high retropalatal (HRP), low retropalatal (LRP), high retroglossal (HRG), and low retroglossal (LRG).

RESULTS

During sleep, the minimum cross-sectional areas decreased 36.5%, 67.8%, 75.5%, and 65.8% at each level of HRP, LRP, HRG, and LRG respectively, as compared with those measured during wakefulness. Mandibular advancement during sleep increased 75.7%, 141.3%, 128.1%, and 119.9% at each level. The oropharynx showed 70.3%, 110.4%, 140.3%, and 156.9% increase in the Collapsibility Indices during sleep at each level of HRP, LRP, HRG, and LRG, respectively, compared with wakefulness. However, collapsibility indices decreased 29.1%, 23.2%, 21.4%, and 34.1% at each level with mandibular advancement.

CONCLUSION

Mandibular advancement increases oropharyngeal diameter and decreases oropharyngeal collapsibility during midazolam-induced sleep respiration at the retropalatal as well as the retroglossal region in most patients with OSA.

[Update on upper airway evaluation in obstructive sleep apnea]

During the past two decades, different methods of upper airway evaluation for patients with obstructive sleep apnea (OSA) have been investigated. Although clinical assessment is the basis of any diagnostic workflow in OSA, the Mueller maneuver is apparently of no importance. Imaging techniques have increased our knowledge of the pathophysiology of OSA. Cephalometry is done only if maxillomandibular advancement is planned; dynamic investigations such as computed tomography and magnetic resonance imaging are able to picture the pharyngeal collapse and have the capacity to simulate the effect of interventions on OSA severity. So far, video endoscopy under sedation can only predict the success of oral appliances. Multichannel pressure recordings depict the distribution of obstructive events in the upper or lower pharyngeal segment during the entire night. The impact of sophisticated upper airway evaluation remains limited compared with standard clinical assessment. Further research is needed to develop valuable tools for the diagnostic workup of patients with OSA.

Airway and Craniofacial Changes With Mandibular Advancement Device in Chinese With Obstructive Sleep Apnoea

Introduction: The objective of this study was to investigate whether a reduction of obstructive sleep apnoea (OSA) severity is associated with significant airway and craniofacial changes with mandibular advancement device (MAD) in Chinese subjects. Materials and Methods: A total of 14 Chinese subjects (8 males, 6 females) diagnosed with OSA by overnight polysomnography (PSG), were fitted with the MAD. The mean ± standard deviation baseline apnoea-hypopnoea index (AHI) was 38.4 ± 17.2 and minimum arterial oxygen saturation (SaO2) was 75.5 ± 11.1%. The second lateral cephalogram was taken (wearing the MAD) after the second PSG. The second PSG was indicated when symptoms have improved as shown by the Epworth Sleepiness Score and sleep questionnaire after wearing the MAD for 1 month. Comparison of cephalometric variables was done to evaluate the effects of the MAD on the upper airway and anatomical variables. Pre-treatment versus post-treatment variables were compared using Wilcoxon signedrank test to determine the statistical significance at the 5% levels. The changes in airway variables were correlated with the changes in AHI using the Spearman correlation test. Results: At the second polysomnogram, AHI was significantly reduced to 10.9 ± 14.7. Minimum SaO2 was significantly increased to 86 ± 8.4%. Mean airway dimension was significantly increased at the nasopharyngeal area from 22.7 ± 3.0 mm to 24.8 ± 2.1 mm. The distance of the hyoid bone to the mandibular plane was significantly reduced with the MAD from a mean of 21.2 ± 5.7 mm to 13.9 ± 7.0 mm (P <0.05). This reduction of the distance of the hyoid bone to the mandibular plane was significantly correlated with the reduction in the AHI. Conclusion: An increase in the nasopharyngeal airway and reduction of the distance of the hyoid bone to the mandibular plane was observed for this sample of Chinese OSA subjects. This study forms the baseline for future studies on the effects of MAD on the airway and craniofacial structures in a larger sample. Key words: Lateral cephalogram, Mandibular advancement splint, Mandibular advancement device, Obstructive sleep apnoea, Polysomnogram

Randomised study of three non-surgical treatments in mild to moderate obstructive sleep apnoea

BACKGROUND

Patients with mild to moderate obstructive sleep apnoea (OSA) may be managed with different treatment options. This study compared the effectiveness of three commonly used non-surgical treatment modalities.

METHODS

Subjects with mild to moderate OSA were randomised to one of three treatment groups for 10 weeks: conservative measures (sleep hygiene) only, continuous positive airways pressure (CPAP) in addition to conservative measures or an oral appliance in addition to conservative measures. All overweight subjects were referred to a weight-reduction class. OSA was assessed by polysomnography. Blood pressure was recorded in the morning and evening in the sleep laboratory. Daytime sleepiness was assessed with the Epworth Sleepiness Scale. Health-related quality of life (HRQOL) was assessed with the 36-Item Short-Form Health Survey (SF-36) and Sleep Apnoea Quality of Life Index (SAQLI).

RESULTS

101 subjects with a mean (SEM) apnoea-hypopnoea index (AHI) of 21.4 (1.1) were randomised to one of the three groups. The severity of sleep-disordered breathing was decreased in the CPAP and oral appliance groups compared with the conservative measures group, and the CPAP group was significantly better than the oral appliance group. Relief from sleepiness was significantly better in the CPAP group. CPAP was also better than the oral appliance or conservative measures in improving the "bodily pain" domain, and better than conservative measures in improving the "physical function" domain of SF-36. Both CPAP and the oral appliance were more effective than conservative measures in improving the SAQLI, although no difference was detected between the CPAP and oral appliance groups. CPAP and the oral appliance significantly lowered the morning diastolic blood pressure compared with baseline values, but there was no difference in the changes in blood pressure between the groups. There was also a linear relationship between the changes in AHI and body weight.

CONCLUSION

CPAP produced the best improvement in terms of physiological, symptomatic and HRQOL measures, while the oral appliance was slightly less effective. Weight loss, if achieved, resulted in an improvement in sleep parameters, but weight control alone was not uniformly effective.