基于计算流体力学分析腺样体大小对儿童上气道气流的影响

目的 通过构建同一气道中腺样体大小依次递减的8种上气道有限元数值模型，分析腺样体大小对上气道流场特性的影响，帮助临床医生进一步认识腺样体在小儿鼾症中的发病机制及规范腺样体手术适应证。方法 基于上气道CT扫描图，通过三维重建软件Amira构造相同气道中腺样体大小依次递减的8种上气道三维模型；采用计算流体力学(CFD)模拟各上气道吸气气流；从气流流速、流动方式、气流压强和通气量等方面分析腺样体大小对上气道流场特性的影响。结果 当腺样体肥大阻塞后鼻孔55%以内时，平静吸气气流流速和压强变化趋势与正常气道基本一致，气流流线规则，通气量为77.812~74.854 mL/s。当阻塞度达64%以上时，鼻咽部的气流流速和压降急剧增加，流线紊乱，平静吸气时上气道通气量显著减少。结论 腺样体肥大阻塞后鼻孔达2/3以上时，可严重影响儿童正常吸气。腺样体越大，患儿夜眠憋气、打鼾、呼吸暂停等症状越明显。腺样体肥大是造成儿童阻塞性睡眠呼吸暂停低通气综合征(OSAHS)的重要因素。

Analysis of the effect of adenoid size on upper airway flow in children based on computational fluid dynamics

Objective To analyze the effect of adenoid size on the upper airway flow by constructing 8 different upper airway finite element numerical models with the adenoid size decreasing successively in the same airway, so as to help clinicians to further understand the pathogenesis of adenoid in children with snoring disease and to regulate the indications for adenoid surgery. Methods Based on the computed tomography (CT) of the upper airway, 8 different upper airway three-dimensional (3D) models with decreasing adenoid size in the same airway were constructed by 3D reconstruction software Amira. Computational fluid dynamics (CFD) was used to simulate the inspiratory airflow in each upper airway. The influences of the size of adenoids on the flow field characteristics of the upper airway were analyzed from the aspects of flow velocity, flow pattern, flow pressure and ventilation volume. Results When the adenoid was enlarged and blocked nostril within 55%, the flow velocity and pressure during quiet inspiratory period were basically consistent with the normal airway, the flow line was regular, and the ventilation volume was between 77.812 to 74.854 mL/s. When the degree of obstruction reached more than 64%, the nasopharyngeal airflow velocity and pressure drop sharply increased, with disrupted streamline and significant reduction of upper airway ventilation volume during quiet inspiratory period. Conclusions Adenoid hypertrophy can affect the normal inspiration of children seriously when obstruction of nostril up to 2/3. The larger the adenoids, the more obvious the symptoms of suffocation, snoring, and apnea at night sleep. Adenoid hypertrophy is an important factor that causes obstructive sleep apnea-hypopnea syndrome in children.