| 1.Objective: To establish a three-dimensional numerical model of the middle ear,including the eustachian tube of normal people,to analyze the numerical simulation of the flow field of the eustachian tube and middle ear cavity under the influence of external force,to calculate the response value of air pressure in the tube when the eustachian tube of normal people is open.By changing the pressure value of the eustachian tube pharynx mouth and then analyze the changes of the pressure in the middle ear cavity;then man-made changes in the model,the eustachian tube mechanical occlusion in patients with eustachian tube numerical model,under the same conditions for the numerical simulation of airflow field,to contrast normal people and patients with mechanical obstruction of eustachian tube,analysising of the calculation of the numerical,make sure that what the impact of middle ear pressure do it make with eustachian tube dysfunction and analysis how eustachian tube blowing surgery improve the situation of middle ear pressure,providing new ideas and methods for eustachian tube dysfunction treatment and prevention.2.Methods: One normal adult female in our country was used as an example to obtain the imaging data by CT scan.The 3D numerical model including nasopharyngeal,eustachian tube,middle ear cavity and mastoid was established by three-dimensional reconstruction software Mimics 20.0,using Geomagic Studio 12.0 software to smooth the model,construct grille,fitting surface treatment,and finally use the mechanical analysis software ANSYS15.0 to numerical simulation and analysis of eustachian tube airflow field in normal people.The changes of pressure in the middle ear cavity under different external forces were analyzed by giving the different pressure inlet of the model.The model was modified in Geomagic Studio 12.0 to simulate the eustachian tube morphology in patients with obstructive eustachian tube dysfunction,and the same method and numerical simulation were used to deal with the model.Finally,the numerical results of normal and eustachian tube dysfunction patients were compared.3.Results1)Eustachian tube length and cross-sectional area under normal open conditions: the eustachian tube length was measured 38.27 mm,bone length 9.83 mm,cartilage length 28.44 mm,cross section area of pharynx of eustachian tube 71.71 mm 2,cross section area of tympanic opening of auditory tube 10.37 mm 2,cross-sectional area of the most narrow part of the eustachian tube 1.13 mm 2.2)In normal Chinese,when gas flow from the pharynx of eustachian tube to the middle ear tympanic cavity,the pressure from the pharynx of eustachian tube to the most narrow parts of the eustachian tube lumen was gradually reduced,the smallest pressure was in the narrowest part of the eustachian tube,the pressure from the most narrow parts to the tympanic cavity was gradually increased.When the Eustachian tube lumen opening,pharynx of eustachian tube was given 3300 pa pressure,the middle ear cavity pressure is 583 pa of normal Chinese;the middle ear cavity pressure is 503 pa of eustachian tube dysfunction patients,which compared with normal decreased 80 pa.3)When the pressures of 8300 pa,13400pa,18400 pa,23500pa and 33600 pa were given to pharynx of eustachian tube in the three-dimensional model of normal people and patients with eustachian tube dysfunction,the pressure in middle ear cavity of normal people were 1662 pa,2827 pa and 3993 pa,5251 pa,7752 pa;the pressure in the middle ear cavity of patients with eustachian tube dysfunction was 1469 pa,2490 pa,3487 pa,4664 pa,6283 pa.From this we can conclude that with the increasing pressure in the eustachian tube,the pressure in the middle ear cavity increases continuously.4)By comparing the pressure of the middle ear cavity of normal people and patients with eustachian tube dysfunction under the same inlet pressure,it can be seen that the pressure of the middle ear cavity of patients with obstructive eustachian tube dysfunction is always less than the pressure of the middle ear cavity of normal people.4.Conclusion1)A three-dimensional numerical model including the eustachian tube pharyngeal,eustachian tube cartilage,eustachian tube isthmus,eustachian tube bone,eustachian tube tympanic cavity,middle ear tympanic cavity and mastoid was established.Analysis of the influence of eustachian tube dysfunction on the pressure in the middle ear and the biomechanical characteristics of eustachian tube blowing,providing new ideas and new methods for the prevention and treatment of eustachian tube dysfunction.2)When the pharyngeal of the eustachian tube is opening in normal people,the nasopharyngeal gas enters the middle ear cavity through the eustachian tube,and it balances the pressure between the middle ear cavity and outside air.This experiment has obtained the corresponding airflow field data.3)When eustachian tube dysfunction,the resistance of the eustachian tube pharyngeal has increased,it leads to and changes in the characteristics of the airflow field,which are the important factors in the occurrence of middle ear disease.4)Eustachian tube blowing can improve the pressure of the middle ear cavity,and the pressure in the middle ear cavity increases when the pressure of blown tension is increasing,which helps to relieve the negative pressure in the middle ear cavity.However,corresponding quantitative indicators are needed in clinical practice. |
