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Simulation of the upper airways in patients with obstructive sleep apnea and nasal obstruction: A novel finite element method.

ABSTRACT: Objective:To evaluate the biomechanical properties of the soft palate and velopharynx in patients with obstructive sleep apnea (OSA) and nasal obstruction. Study design:Prospective experimental study. Materials and methods:Two finite element (FE) models of the soft palate were created in six patients undergoing nasal surgery, one homogeneous model based on CT images, and one layered model based on soft tissue composition. The influence of anatomy on displacement caused by a gravitational load and closing pressure were evaluated in both models. The strains in the transverse and longitudinal direction were obtained for each patient. Results:The individual anatomy influences both its structural stiffness and its gravitational displacement. The soft palate width was the sole anatomical parameter correlated to the critical closing pressure, but the maximal displacement due to gravity may have a relationship to closing pressure of possibly an exponential order. The airway occlusion occurred mainly at the lateral attachments of the soft palate. The total transverse strain showed a strong correlation with maximal closing pressure. There was no relationship between the critical closing pressure and the preoperative AHI levels, or the change in AHI after surgery. Conclusion:Hyperelastic FE models both in the homogeneous and layered model represent a novel method of evaluating soft tissue biomechanics of the upper airway. The obstruction occurs mainly at the level of the lateral attachments to the pharyngeal wall, and the width of the soft palate is an indicator of the degree of critical closing pressure. A less negative closing pressure corresponds to small total transverse strain. The effect of nasal surgery on OSA is most likely not explained by change in soft palate biomechanics. Level of Evidence:NA.

SUBMITTER: Henrik Strand Moxness M

PROVIDER: S-EPMC5915829 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Simulation of the upper airways in patients with obstructive sleep apnea and nasal obstruction: A novel finite element method.

Henrik Strand Moxness Mads M Wülker Franziska F Helge Skallerud Bjørn B Nordgård Ståle S

Laryngoscope investigative otolaryngology 20180221 2

<h4>Objective</h4>To evaluate the biomechanical properties of the soft palate and velopharynx in patients with obstructive sleep apnea (OSA) and nasal obstruction.<h4>Study design</h4>Prospective experimental study.<h4>Materials and methods</h4>Two finite element (FE) models of the soft palate were created in six patients undergoing nasal surgery, one homogeneous model based on CT images, and one layered model based on soft tissue composition. The influence of anatomy on displacement caused by a ...[more]

PMID: 29721539

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Project description:Study objectivesDrug-induced sleep endoscopy (DISE) using propofol is commonly used to identify the pharyngeal structure involved in collapse among patients with obstructive sleep apnea. DISE has never been compared with zolpidem-induced sleep endoscopy. We hypothesized that propofol at recommended sedation levels does not influence upper airway collapsibility nor the frequency of multilevel pharyngeal collapse as compared with zolpidem-induced sleep.MethodsTwenty-one patients with obstructive sleep apnea underwent polysomnography and sleep endoscopy during zolpidem-induced sleep and during DISE with propofol. A propofol target-controlled infusion was titrated to achieve a bispectral index between 50 and 70. Airway collapsibility was estimated and compared in both conditions by peak inspiratory flow and the magnitude of negative effort dependence. Respiratory drive was estimated by the difference between end-expiratory and peak-negative inspiratory pharyngeal pressure (driving pressure). Site and configuration of pharyngeal collapse during zolpidem-induced sleep and DISE with propofol were compared.ResultsThe frequency of multilevel collapse during zolpidem-induced sleep was similar to that observed during DISE with propofol (72% vs 86%, respectively; difference: 14%; 95% confidence interval: -12% to 40%; P = .453). The endoscopic classification of pharyngeal collapse during both conditions were similar. Peak inspiratory flow, respiratory drive (effect size: 0.05 and 0.03, respectively), and negative effort dependence (difference: -6%; 95% confidence interval: -16% to 4%) were also similar in both procedures.ConclusionsIn this pilot study, recommended propofol doses did not significantly increase multilevel pharyngeal collapse or affect upper airway collapsibility and respiratory drive as compared with zolpidem-induced sleep.Clinical trial registrationRegistry: clinicaltrials.gov; Name: Natural and Drug Sleep Endoscopy; URL: https://clinicaltrials.gov/ct2/show/study/NCT03004014; Identifier: NCT03004014.

Project description:Importance:Adenotonsillar hypertrophy is an important cause of obstructive sleep apnea (OSA) in children. However, residual OSA and abnormal polysomnographic findings have been reported in up to 75% of cases after adenotonsillectomy. Other anatomical and functional factors that influence upper airway structures, including the lateral pharyngeal wall, have rarely been studied in children with OSA. Objective:To determine whether the upper airway structures can be evaluated using head and neck ultrasonography and if there is an association between the ultrasonographic measurements for these structures and severity of OSA seen on polysomnography in children. Design, Setting, and Participants:Prospective, single-center, observational study of 82 children younger than 18 years with a diagnosis of sleep-disordered breathing (20 with primary snoring, 62 with OSA, as determined by the apnea-hypopnea index) and admitted to a tertiary teaching hospital for adenotonsillectomy. Exposures:Ultrasonography and polysomnography. Main Outcomes and Measures:Ultrasonographic measurements of upper airway structures. Results:Of the 82 children studied, 62 (76%) were boys; mean (SD) age, 7.7 (6.2). There was no significant difference found in tonsillar dimensions or volume between the children with OSA and those with primary snoring. However, the mean (SD) total lateral pharyngeal wall and the total neck thicknesses at the retropalatal level were both greater in children with OSA than in those with primary snoring at rest (24.9 [4.4] mm vs 21.3 [2.6] mm; difference, 3.61 mm; 95% CI of difference, 1.48-5.74 mm for lateral pharyngeal wall; and 59.9 [14.4] mm vs 49.9 [11.2] mm; difference, 10.9 mm, 95% CI of difference, 3.8-17.9 mm for the total neck). Conclusions and Relevance:Estimated tonsillar volume measured using ultrasonography had no relationship with the apnea-hypopnea index in childhood sleep-disordered breathing. However, the lateral pharyngeal wall was significantly thicker in children with OSA than in those with primary snoring at rest.

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Simulation of the upper airways in patients with obstructive sleep apnea and nasal obstruction: A novel finite element method.

Publications

Simulation of the upper airways in patients with obstructive sleep apnea and nasal obstruction: A novel finite element method.

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