摘要目的 比较周期性呼吸状态与稳态呼吸状态下正常鼻腔气流的流场特点.方法 根据正常成人鼻腔的CT扫描,利用计算流体力学软件Fluent建立正常的鼻腔模型,模拟周期性呼吸下鼻腔的气流状况,选取其中某些时刻(呼气加速区第15.600秒、呼气减速区第16.495秒)的气流状态与相同流量下稳态呼气状态下的气流状态进行比较.结果 周期性呼吸时第15.600秒与入口流量为697.25ml/s稳态呼气情况下鼻腔气流参数如下:两种呼吸状态下,左鼻腔主要通道气流的平均速度、最大速度和压强相近,各鼻窦内气流的平均速度相近;气流分布均以总鼻道和中鼻道为主,两者分别占气流总流量的50%和30%以上;两种呼吸状态下,下鼻道和总鼻道下部的气流流线均以直线为主,中鼻道、上鼻道和总鼻道中上部的气流流线呈抛物线形.周期性呼吸第16.495秒(距离交界点0.005 s)时鼻腔气流平均速度为0.0706 m/s,气流在鼻咽和鼻阈等宽阔区域形成大范围的涡旋运动;而入口流量为7.62 ml/s稳态呼气时左鼻腔气流的平均速度为0.0415 m/s,鼻腔气体的流动与高流量时相似.结论 在相同流量时,除在呼气和吸气交界点附近外,周期性呼吸和稳态呼吸状态下鼻腔气流流动的各参数相似.

abstractsObjective To compare the characteristics of normal nasal airflow during periodic breathing and steady-state breathing. Methods Fluent software was used to simulate the nasal cavity and paranasal sinus structures following CT scanning of a normal adult subject. Air flow velocity, pressure,distribution and streamlines were calculated and compared during periodic breathing and steady-state breathing. Results The same flux, the performance of nasal airflow on 15. 600 s of periodic breathing and steady-state expiratory( entrance flow was 697. 25 ml/s) were as follows: air flow in the common and middle meatus accounted for more than 50% and 30% of total nasal cavity flow during two respiratory status. Flow velocity and pressure of nasal cavity and each paranasal sinus were extremely similiar. The flow trace during two respiratory status in the inferior and lower part of the common meatus were predominately straight in form. Flow were parabolic in the middle and superior meatus and the middle and upper parts of the common meatus. The flow trace of nasal airflow on 16. 495 s of periodic breathing had wide areas vortex in nasopharynx and limen nasi, the average speed was 0. 0706 m/s, while the entrance flow 7. 62 ml/s stable state of the left nasal expiratory, the average speed was 0.0415 m/s, the flow trace was similar to 697. 25 ml/s. Conclusion The same flow, except in the junction of the respiratory cycle, the performance of normal nasal airflow during periodic breathing and steady-state breathing were similar.