鼻腔结构形态对鼻腔气流的影响

Structure of nasal cavity and characters of airflow

目的对20名健康志愿者的鼻腔结构进行三维重建,并对其气流进行数值模拟,从而了解气流在不同鼻腔中的流动情况。方法根据20名健康志愿者的鼻腔CT影像,用表面重建的方法对其鼻腔结构进行三维重建,用有限单元的方法对三维模型中的气流进行数值模拟。用鼻声反射测量仪对8名志愿者进行测试并记录有关数据。对比鼻声反射测得的曲线和数值模拟的结果,并用流体网络流的理论对得到的结果进行解释。结果从数值模拟结果的速度云图中可以得到每一侧鼻腔中的气流分布情况,气流主要由总鼻道流过,占总流量的50%～77%;从压力云图中可以得到鼻腔不同部位的气压值情况,鼻阈处产生的鼻阻力占鼻腔总鼻阻力的50%～65%,通过对比分析可以得出鼻腔冠状位截面积的变化与气流的速度和压强分布的关系。结论鼻腔中气流的分布不是固定的,每个人的鼻腔结构不同导致了气流分布的不同。

Objective To study the airflow in nasal cavity by reconstructing 20 volunteers＇ nasal cavity models and numerical simulation of the flow field in these nasal cavity models. Methods Based on the data from the CT images, 20 volunteers＇ nasal cavity models were reconstructed by the method of surface rendering. The flow field in these three-dimensional models were simulated with finite element method. Some of these volunteers were tested by means of acoustic rhinometer and the test results recorded. Comparisons were performed for the curves from acoustic rhinometer and the results of numerical simulations. The simulation results were explained with the fluid network theory. Results The airflow distribution in the nasal cavity model could be acquired from the simulation results of the velocity plot. Main airflow would pass through the common nasal meatus in which flux accounted for 50% - 77% of overall flux. The pressure value at any point in the nasal cavity model could be obtained from the results of the pressure plot. The nasal airway resistance in the region of limen nasi accounted for 50% - 65% of overall nasal airway resistance. Comparing the test results with the simulation results the relation could be understood between the change of the cross-section area of nasal cavities and the plot of numerical simulation results of velocity and pressure in airflow field in the nasal cavity models. Conclusions Comparing the simulated results of the 20 volunteers＇ nasal cavity model it can be concluded that the distribution of airflow in nasal cavities is not stationary. The differences among everybody＇s nasal cavity structure lead to the different airflow distribution in the nasal cavities.