Increase In Upper Airway Volume Research Articles

Effects of twin-block appliance on upper airway parameters in OSA children with class II malocclusion and mandibular retrognathia: a CBCT study.

Correction of class II mandibular retrognathic skeletal malocclusion with twin-block appliance resulted in a significant increase in upper airway volume, MCA, anteroposterior and lateral distances of the MCA at the level of the oropharynx, MCA at the level of the hypopharynx and upper airway length, and a significant decrease in AHI, but it had no effect on nasopharynx parameters. • CBCT imaging has been shown to be an effective and precise diagnostic tool for analyzing the upper airways and craniofacial structures. • Twin block appliance may be an effective treatment modality in children with OSA. • Minimal cross-sectional area of upper ways may be the most relevant potential parameter when explaining how the upper airway anatomy plays role of in the pathogenesis of pediatric OSA. • Twin block appliance induced favorable changes in upper airway morphology (oropharynx area mainly) and respiratory parameters in OSA children with class II malocclusion.

Clinical impact of two types of mandibular retention devices - A CAD/CAM design and a traditional design - On upper airway volume in obstructive sleep apnea patients

ObjectiveThis pilot randomized crossover study evaluated the outcomes of two custom-made mandibular retention devices (MRDs), a computer-aided design (CAD)/computer-aided manufacturing (CAM) device (Narval CC™) and a non-CAD/CAM device (Narval™), on oropharyngeal airway volume in patients with obstructive sleep apnoea (OSA). Methods12 OSA patients were recruited from an University Hospital for MRD therapy with either CAD/CAM or non-CAD/CAM first. A cone-beam computed tomography evaluation (CBCT) and polysomnography assessment was performed during baseline assessment and at the end of each study period. ResultsUpper airway volume increased significantly with the CAD/CAM device (7725 +/- 6540 mm3, p = 0.008) but not with the non-CAD/CAM device (3805 +/- 7806 mm3, p = 0.13). The CAD/CAM device was also associated with a significant decrease in AHI (mean AHI after treatment 9.4±6.7 events/h, p = 0.003) and oxygen desaturation index (mean ODI of ≥ 3%/h 11.9 ± 6.8, p = 0.011). Changes in AHI (14.7 +/- 11.7 events/h, p = 0.083) and ODI (15.5 +/- 19.2, p = 0.074) were not statistically significant with the non-CAD/CAM device. The vertical dimension of occlusion increased significantly following treatment with both MRD devices (both p = 0.003), but was significantly less pronounced with the CAD/CAM device (mean difference: -2.7 +/- 1.7 mm, p = 0.003). Final mandibular protrusion after titration was the same with both devices (85%, p = 0.317). ConclusionThe CAD/CAM (Narval CCTM) device was associated with a significant increase in upper airway volume that may be caused by a lower degree of vertical separation between the jaws when compared to the non-CAD/CAM design.

Hyoid expansion with titanium plate and screws with hyomandibular suspension: A study on human cadavers with computed tomographic comparative analysis.

Objective(s)Obstructive sleep apnoea is characterized by repetitive obstruction of the upper airway during sleep. These repeated oxygen desaturations increase cardiovascular and cerebrovascular morbidity and mortality significantly. Upper airway surgery is an option for patients who fail continuous positive airway pressure therapy. Airway collapse is usually multilevel and hypopharyngeal collapse is a challenging area to address. It is hypothesized that hyoid expansion with hyomandibular suspension can potentially increase upper airway dimensions at the hypopharynx. This study aims to document the effect of hyoid expansion using titanium plate and screws with hyomandibular suspension on hypopharyngeal airway dimensions. It is an anatomical feasibility study performed using 10 human cadaver heads.MethodsThe hyoid bone is trifractured. The expanded hyoid is then suspended to the mandible. Computed tomography (CT) scans were performed on the cadavers to measure the airway dimensions before and after the procedure.ResultsThis procedure resulted in statistically significant increase in airway dimensions at the level of the hypopharynx in all 10 human cadaver heads. Increase in cross‐sectional area correlated significantly with increase in 3‐dimentional (3D) volume.The mean area of the airway at the level of the hyoid increased from 999.3 ± 193.0 mm2 to 1241.4 ± 103.2 mm2. Statistically significant increase in upper airway volume based on 3D reconstruction was also noted. Upper airway volume increased from 6.94 ± 6.46 mL to 13.58 ± 8.29 mL.ConclusionAirway dimensions increased with hyoid expansion and hyomandibular suspension in our cadaveric study measured using CT scans. Further studies are needed to see if this technique can be translated to clinical use in live patients.Level of evidenceNA.

Tridimensional upper airway assessment in male patients with OSA using oral advancement devices modifying their vertical dimension.

Mandibular advancement devices (MADs) constitute an alternative treatment in selected patients with OSA. A mandibular advanced position has been suggested to be beneficial, whereas its combination with an increased bite-raise may increase its adverse effects. The objective of this study was to assess upper airway (UA) volume and inspiratory pressure gradient variations in a group of 17 patients with OSA. The study was performed under 3 mandibular positions: intercuspal position (P1), MAD position in closed mouth (P2), and MAD position with an increased bite-raise (P3). We conducted a 3-dimensional reconstruction of the pharynx using the finite element method via a computed tomography scan and the subsequent calculation using fluid-dynamic analysis. One hundred percent of the patients showed an increase in UA volume in both P2 and the MAD position with an increased bite-raise, P2 being the position where 76.47% of the patients showed the largest UA volume. P2/velopharynx was the position/region where the largest UA volume increase was achieved (4.73 mm³). A better gradient in P2 (mean = 0.62) in 58.82% of the patients and a better gradient in P3 (mean = 0.74) in 41.18% of patients respect P1 was observed. In 82.35% of patients, a better volume-pressure gradient match was also found. The best efficiency scores for both volume increase and better inspiratory pressure gradient were obtained in P2. This study findings suggest that in a MAD, the minimal bite opening position necessary for mandibular protrusion is more effective in increasing airway volume and inspiratory gradient compared to a larger bite-raising (15 mm).

Effects of a fixed functional appliance on upper airway volume: A 3-dimensional cone-beam computed tomography study

Although functional appliances (FAs) are primarily used to treat Class II malocclusions, their effects on the upper airway have generally been reported in studies involving 2-dimensional analysis of cephalometric radiographs. This study aimed to use 3-dimensional cone-beam computed tomographyto (1) determine the effects on upper airway volume and minimum cross-sectional area (MCA)when an FA is used for orthodontic treatment and (2) identify pretreatment markers for airway changes. Pre- and posttreatment cone-beam computed tomography scans were selected from 73 children whose orthodontic treatment involved using a fixed FA (37 girls and 36 boys; mean age 12.0years); a control group was constituted and included the scans of 73 children who were matched for chronological age, skeletal age, sex, and mandibular inclination and who received orthodontic treatment for minor malocclusions without an FA. Changes in upper airway volume and MCA were evaluated by a standardized, previously validated method analyzed with mixed-effects linear regression. Upper airway volume and MCA increased over time for both the FA and the matched control groups (P<0.05). The FA caused an additional significant increase in upper airway volume and MCA (P<0.0001) when compared with the control group. An increased ANB angle, a reduced mandibular inclination, and a reduced skeletal age pretreatment had a positive effect on upper airway volume and MCA (P<0.05). A fixed FA was associated with a significant increase in upper airway volume and MCA in children when compared with controls. Pretreatment ANB angle, skeletal age, and mandibular inclination may be predictors for positive changes in the upper airway. The results may prove valuable in treating children with Class II malocclusions with compromised upper airways.

UPPER AIRWAY VOLUMETRIC CHANGE FOLLOWING THE USE OF TWO CAD/CAM ORAL APPLIANCES FOR TREATMENT OF OBSTRUCTIVE SLEEP APNEA

Introduction: Obstructive sleep apnea (OSA) is a condition in which there is repetitive and intermittent occlusion of the upper airway (UA) during sleep. OSA can be treated through; continuous positive airway pressure (CPAP), surgery, or oral appliances. Mandibular Advancement Appliance (MAA) is considered a valid alternative, which can be the first choice in simple snorers and mild-moderate OSA. MAA can be either custom-made or non-custom-made, one-piece or two-piece, titratable or non-titratable. While Monoblock designs permit no mouth opening, two-piece appliances vary in permissible lateral jaw movement and in the coupling mechanisms which attach the two plates together. Objectives: measuring the change in UA volume after the use of two different designs of MAA (Monoblock and Biblock) Materials and methods: Twenty patients with diagnosed OSA were divided randomly into two equal groups: Monoblock group ; received Monoblock MAA fabricated using CAD/CAM technique at different advancement levels; 50% then 75% of maximum advancement, Biblock group; received Biblock MAA fabricated using CAD/CAM technique at different advancement levels; 50% then 75% of maximum advancement. UA volume of all patients were evaluated after three months of acclimatization of each stage of advancement through Cone-Beam Computed Tomography (CBCT). Results: Biblock group showed statistically significant increase in UA volume at 75% mandibular advancement level, compared to Monoblock group (p=.001). There was statistically significant increase in UA volume percentage change from baseline to 50% advancement (p=.016), and also from baseline to 75% advancement (p=.001) in favor to Biblock MAA. Conclusions: Both Monoblock and Biblock MAA produced statistically significant increase in UA volume of OSA patients. Biblock MAA with elastics presented statistically significant favorable increase in UA volume in relation to Monoblock MAA.

0636 NON-SURGICAL, UPPER AIRWAY REMODELING FOR UARS

Upper airway resistance syndrome has become a prevalent form of sleep-disordered breathing. The causes for UARS include decreased pharyngeal muscle tone, and craniofacial deficiencies amongst others. Current methods used to manage UARS - include no standard medical treatment; continuous positive airway pressure (CPAP) therapy and/or mandibular advancement appliances have been used without any results. Therefore, this study is to test the hypothesis that a biomimetic oral appliance therapy (BOAT) can be used followed by a DNA appliance, with a forward facial head-gear mask. This pilot study included two adults: 2 females, 29 years and 32 years, (mean age 31yrs.) diagnosed with UARS to mild OSA who were treated with FDA-cleared BOAT (MRNA appliance®) followed with a forward facial mask for osseous remodeling. Prior to treatment the craniofacial region was imaged using 3D cone-beam CT scans. After 9 to 15 months of treatment, the upper airway volume was reassessd with 3D cone-beam CT scans and upper airway analysis. For case 1, the upper airway volume (from the posterior nasal spine to the epiglottis) prior to treatment was 9.28cm 3 and increased to 16cm 3, representing a 29% increase in upper airway volume. For case 2, upper airway volume increased from 16.7cm 3 prior to treatment to 20.5cm 3 post-treatment, showing a 12.5% increase in upper airway volume. By subjective questionnaires of before and after, the patients have improved immensely. This preliminary study indisputably suggests that increases in 3D airway may be associated with non-surgical upper airway remodeling for UARS in adults with craniofacial deficiencies. None

Mechanical ventilation causes airway distension with proinflammatory sequelae in mice.

The pathogenesis of ventilator-induced lung injury has predominantly been attributed to overdistension or mechanical opening and collapse of alveoli, whereas mechanical strain on the airways is rarely taken into consideration. Here, we hypothesized that mechanical ventilation may cause significant airway distension, which may contribute to the pathological features of ventilator-induced lung injury. C57BL/6J mice were anesthetized and mechanically ventilated at tidal volumes of 6, 10, or 15 ml/kg body wt. Mice were imaged by flat-panel volume computer tomography, and central airways were segmented and rendered in 3D for quantitative assessment of airway distension. Alveolar distension was imaged by intravital microscopy. Functional dead space was analyzed in vivo, and proinflammatory cytokine release was analyzed in isolated, ventilated tracheae. CT scans revealed a reversible, up to 2.5-fold increase in upper airway volume during mechanical ventilation compared with spontaneous breathing. Airway distension was most pronounced in main bronchi, which showed the largest volumes at tidal volumes of 10 ml/kg body wt. Conversely, airway distension in segmental bronchi and functional dead space increased almost linearly, and alveolar distension increased even disproportionately with higher tidal volumes. In isolated tracheae, mechanical ventilation stimulated the release of the early-response cytokines TNF-α and IL-1β. Mechanical ventilation causes a rapid, pronounced, and reversible distension of upper airways in mice that is associated with an increase in functional dead space. Upper airway distension is most pronounced at moderate tidal volumes, whereas higher tidal volumes redistribute preferentially to the alveolar compartment. Airway distension triggers proinflammatory responses and may thus contribute relevantly to ventilator-induced pathologies.

The Assessment of Midface Distraction Osteogenesis in Treatment of Upper Airway Obstruction

Le Fort III osteotomy with midface distraction osteogenesis (Le Fort III DO) can improve the midface form and change the upper airway space. Some surgeons believe that midface advancement can improve respiratory outcome dramatically, but others think it does not predictably result in the cure of obstructive sleep apnea (OSA). In this study, we evaluated the structural and functional changes of the upper airway before and after Le Fort III DO; we hope these studies can improve future protocols for midface advancement. A retrospective study of 11 patients with severe midface retrusion who underwent Le Fort III osteotomy with midface external distractor system was undertaken. These patients had an average of 5.4 months of follow-up. Three-dimensional volumetric assessment of the upper airway was used before and after surgery. We also evaluated the two-dimensional cross-sectional area of the upper airway to show the changes in different airway levels. Two patients with preoperative evidence of OSA were evaluated both preoperatively and postoperatively by overnight polysomnography. The midface was distracted for an average of 20.27 +/- 8.04 mm. Comparison between preoperative and postoperative three-dimensional computed tomographic data showed an average 64.30% increase in upper airway volume, an improvement of 9.13 +/- 6.94 mL (P < 0.05). The two-dimensional measurement also showed that the cross-sectional area at the posterior nasal spine and uvula airway level increased (P < 0.05), but the cross-sectional area at the epiglottis level and the separation of airway and esophagus level did not increase (P > 0.05). Two patients with preoperative evidence of OSA had both preoperative and postoperative sleeping studies that showed improvement. Le Fort III DO can significantly improve the upper airway space in the cases of syndromic craniosynostosis. The upper airway space above the uvula level was significantly enlarged after Le Fort III DO according to two-dimensional and three-dimensional image measurements, and according to the polysomnography, the OSA was alleviated. Le Fort III DO is a promising procedure in the treatment of severe midface retrusion with OSA in young patients.

Functional imaging using computational fluid dynamics to predict treatment success of mandibular advancement devices in sleep-disordered breathing

Mandibular advancement devices (MADs) have emerged as a popular alternative for the treatment of sleep-disordered breathing. These devices bring the mandibula forward in order to increase upper airway (UA) volume and prevent total UA collapse during sleep. However, the precise mechanism of action appears to be quite complex and is not yet completely understood; this might explain interindividual variation in treatment success. We examined whether an UA model, that combines imaging techniques and computational fluid dynamics (CFD), allows for a prediction of the treatment outcome with MADs. Ten patients that were treated with a custom-made mandibular advancement device (MAD), underwent split-night polysomnography. The morning after the sleep study, a low radiation dose CT scan was scheduled with and without the MAD. The CT examinations allowed for a comparison between the change in UA volume and the anatomical characteristics through the conversion to three-dimensional computer models. Furthermore, the change in UA resistance could be calculated through flow simulations with CFD. Boundary conditions for the model such as mass flow rate and pressure distributions were obtained during the split-night polysomnography. Therefore, the flow modeling was based on a patient specific geometry and patient specific boundary conditions. The results indicated that a decrease in UA resistance and an increase in UA volume correlate with both a clinical and an objective improvement. The results of this pilot study suggest that the outcome of MAD treatment can be predicted using the described UA model.

A Novel Volumetric Magnetic Resonance Imaging Paradigm to Study Upper Airway Anatomy

We utilized novel three-dimensional volumetric analysis techniques with magnetic resonance imaging (MRI) to study the upper airway and surrounding soft-tissue structures. These MRI techniques allowed us to objectively quantify the volume of the tongue, soft palate, parapharyngeal fat pads, and lateral pharyngeal walls. We first validated our volumetric imaging techniques on a phantom and then demonstrated that our results were reliable and reproducible in normal subjects who did not lose weight. Finally, we studied 12 obese, nonapneic women during wakefulness before and after weight loss. We hypothesized that our novel magnetic-resonance computer-reconstruction techniques would allow us to detect small reductions in the volume of the tongue, soft palate, lateral pharyngeal walls, and parapharyngeal fat pads and increases in the volume of the upper airway with weight loss. University medical center. Normal controls and 12 obese nonapneic women. Weight loss. Following a mean 17.1+/-8.62 kg (17.3%) reduction in weight, upper airway volume increased (p = 0.06) in both the retropalatal and retroglossal regions. This increase in upper airway volume was mediated by significant reductions in the volume of the lateral pharyngeal wall (p = 0.0001) and parapharyngeal fat pads (p = 0.001). However, the volume of the tongue (p = 0.35) and soft palate (p = 0.39) were not reduced significantly with weight loss. These data indicate that volumetric MRI is a powerful tool to study anatomic changes in the upper airway and surrounding soft-tissue structures and is sensitive enough to detect changes in these structures.