Upper Airway Elasticity Estimation in Pediatric Down Syndrome Sleep Apnea Patients Using Collapsible Tube Theory

Abstract

Elasticity of the soft tissues surrounding the upper airway lumen is one of the important factors contributing to upper airway disorders such as snoring and obstructive sleep apnea. The objective of this study is to calculate patient specific elasticity of the pharynx from Magnetic Resonance (MR) images using a ‘tube law’ i.e. the relationship between airway cross-sectional area and transmural pressure difference. MR imaging was performed under anesthesia in children with Down syndrome (DS) and obstructive sleep apnea (OSA). An airway segmentation algorithm was employed to evaluate changes in airway cross-sectional area dilated by continuous positive airway pressure (CPAP). A pressure-area relation was used to make localized estimates of airway wall stiffness for each patient. Optimized values of patient specific Young’s modulus for tissue in the velopharynx and oropharynx, were estimated from finite element (FE) simulations of airway collapse. Patient specific deformation of the airway wall under CPAP was found to exhibit either a non-linear ‘hardening’ or ‘softening’ behavior. The localized airway and tissue elasticity were found to increase with increasing severity of OSA. Elasticity based patient phenotyping can potentially assist clinicians in decision making on CPAP and airway or tissue elasticity can supplement well-known clinical measures of OSA severity.

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Clinical application of MRI-respiratory gating technology in the evaluation of children with obstructive sleep apnea hypopnea syndrome

“…Accordingly, to explore changes in the nasopalatine pharyngeal cavity in pediatric OSAHS, we performed upper airway MRI during sleep. As dynamic changes in soft palate morphology during respiration represent an important pathogenic factor in OSAHS, [ 17 ] we focused our studies on the nasopalatine pharyngeal cavity above the plane of the soft palate. In order to exclude multiple confounding factors, our study population included pediatric OSAHS patients with adenoidal hypertrophy alone.…”

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“…They concluded that elasticity-based patient phenotyping can potentially assist clinicians in decision making on the level of continuous positive airway pressure. 39 Our study has several limitations that should be acknowledged. First, as already stated, the sample size was rather limited, which prevented the use of logistic regression and the comparison of FRI against clinical markers.…”