[Establishment and digital simulation of upper airway in patients with adenoid hypertrophy].

Objective: To analyze the flow field characteristics of the upper airway in patients with different adenoid hypertrophy using computational fluid dynamics (CFD). Methods: From November 2020 to November 2021, the cone-beam CT (CBCT) data of 4 patients [2 males and 2 females,age range 5-7 years, mean (6.0±1.2) years] with adenoid hypertrophy who were hospitalized in the Department of Orthodontics and the Department of Otolaryngology at Hebei Eye Hospital were selected. The degree of adenoid hypertrophy in the 4 patients was divided into normal S1 (A/N<0.6), mild hypertrophy S2 (0.6≤A/N<0.7), moderate hypertrophy S3 (0.7≤A/N<0.9) and severe hypertrophy S4 (A/N≥0.9) according to the ratio of adenoid thickness to the width of nasopharyngeal cavity (A/N). The CFD model of the upper airway was established using ANSYS 2019 R1 software, and the internal flow field of the CFD model was numerically simulated. Eight sections were selected as observation and measurement planes for flow field information. Relevant flow field information includes airflow distribution, velocity variation, and pressure variation. Results: In the S1 model, the maximum pressure difference occurred in the 4th and 5th observation planes (ΔP=27.98). The lowest pressures and the maximum flow rates of S2 and S3 were located in the 6th observation plane. The airflow in S1 and S2 models completely passed through the nasal cavity. In the S3 model, the mouth-to-nasal airflow ratio was close to 2∶1. In S4 model, the airflow completely passed through the mouth; in the S1 and S2 models, hard palates were subjected to a downward positive pressure with a pressure difference of 38.34 and 23.31 Pa, respectively. The hard palates in S3 and S4 models were subjected to a downward negative pressure with a pressure difference of -2.95 and -21.81 Pa, respectively. Conclusions: The CFD model can objectively and quantitatively describe the upper airway airflow field information in patients with adenoid hypertrophy. With the increasing degree of adenoid hypertrophy, the nasal ventilation volume gradually decreased, whereas the oral space ventilation volume gradually increased, and the pressure difference between the upper and lower surfaces of the palate gradually decreased until the pressure became negative.目的： 通过构建腺样体肥大患者上气道计算流体动力学（computational fluid dynamics，CFD）模型并分析其气流流场特征，分析鼻腔气流和口腔气流对硬腭产生的压强差。 方法： 从2020年11月至2021年11月就诊于河北省眼科医院口腔正畸科和耳鼻咽喉科的儿童患者锥形束CT资料中，根据腺样体厚度占鼻咽腔宽度的占位率（A/N）选取腺样体正常（A/N<0.6）、轻度肥大（0.6≤A/N<0.7）、中度肥大（0.7≤A/N<0.9）和重度肥大（A/N≥0.9）的患者锥形束CT资料各1例，其中男性2例，女性2例，年龄（6.0±1.2）岁（5~7岁）。采用ANSYS 2019 R1软件建立上气道CFD模型，并对CFD模型内部流场进行数值模拟。选取第四颈椎平面、第三颈椎平面、枢椎平面、软腭尖平面、寰椎平面、腺样体平面、硬腭鼻腔平面、硬腭口腔平面作为流场信息的观测平面，观测指标包括压强、压强差、气流流速及流量。 结果： 腺样体正常CFD模型最大压强差发生于寰椎平面与软腭尖平面之间，为27.98 Pa；轻度和中度肥大CFD模型压强最小和最大流速均位于腺样体平面。腺样体正常和轻度肥大CFD模型的气流完全通过鼻腔，中度肥大CFD模型口腔-鼻腔气流流量比值接近2∶1，重度肥大CFD模型的气流完全通过口腔。腺样体正常和轻度肥大CFD模型的硬腭受到向下的正压力，压强差分别为38.34和23.31 Pa，中度和重度肥大CFD模型的硬腭受到向下的负压力，压强差分别为-2.95和-21.81 Pa。 结论： CFD模型可客观量化描述腺样体肥大患者的上气道气流流场信息。随着腺样体肥大程度不断增加，鼻腔气流流量逐渐减少、口腔气流流量逐渐增加；硬腭的口腔侧、鼻腔侧所受压强差逐渐减小直至负值。.