| Objective:To obtain the imaging data of the upper airway of a healthy volunteer,and establish a finite element numerical model of the upper airway.On the basis of the numerical model,two kinds of clinical operations,such as bilateral partial middle turbinate resection and bilateral middle turbinate fracture internal displacement,were simulated;To analyze the effects of two kinds of operations on the airflow field and particle field in different olfactory regions of the nasal cavity,explore the effects of different middle turbinate operations on the olfactory function of the nasal cavity.Methods:A healthy adult volunteer was selected to exclude the history of upper airway disease,acquire its upper airway CT thin layer scanning data,used Mimics15.0 software to build the upper airway mask,and further smooth the model,divide the surface and fit the model in Geomegic.Imported the processed model into ICEM for unstructured mesh division and wall region setting,in which the olfactory region is divided into regions,which are named as left nasal cavity A,B,C,D(LA,LB,LC,LD)and right nasal cavity A,B In areas C and D(RA,RB,RC,RD),the air flow is set as incompressible gas,the front nostril is the pressure boundary condition,the glottis is the velocity boundary condition,the upper airway mucosa is smooth and non-displacement wall surface,and the effects of different middle turbinate operations on the particle deposition and airflow field in the upper airway and nasal olfactory region are simulated under the resting state(airflow flow is 15 L/min).Result:1.Characteristics of air flow field before and after middle turbinate surgery:1.1 Before middle turbinate surgery,the volume flow of air in the left and right nasal cavity was 120.3135 cm~3/s and 120.9685 cm~3/s respectively,the volume flow of air through the left and right olfactory areas was 1.8249 cm~3/s and 3.0024 cm~3/s respectively,and the volume flow of air in the left and right middle nasal passages was12.5779 cm~3/s and 14.7204 cm~3/s respectively.The volume flow of gas in the left and right nasal cavity after the internal displacement of bilateral middle turbinate fracture was 112.8664 cm~3/s and 125.8365cm~3/s respectively,and the volume flow of gas through the left olfactory region was1.5680 cm~3/s,and the volume flow of gas in the right olfactory region was 3.6950 cm~3/s;The volume flow of left and right middle nasal meatus was 21.8175 cm~3/s and 18.9709cm~3/s respectively.After partial resection of bilateral middle turbinate,the volume flow of left and right nasal cavity was 119.8692 cm~3/s and 122.1461 cm~3/s respectively,the volume flow of left and right olfactory region decreased to 1.2102 cm~3/s and 1.9004 cm~3/s,and the volume flow of left and right middle nasal canal increased to 29.4637 cm~3/s and29.6670 cm~3/s respectively.1.2 The average velocity of air flow through the left and right olfactory areas before middle turbinate surgery was 0.25 m/s and 0.29 m/s respectively.After the operation of bilateral middle turbinate fracture internal displacement,the average airflow velocity in the left and right olfactory regions was 0.26 m/s and 0.40m/s,while the airflow in the nasal olfactory region shifted to the middle turbinate side.After partial resection of bilateral middle turbinate,the average airflow velocity in the left and right olfactory areas was 0.20 m/s and 0.18 m/s respectively.The airflow streamline in the front of the left and right middle nasal passages was more disordered than that before operation.1.3 The maximum WSS in the olfactory region of the left and right nasal cavity before surgery was 0.1820 Pa and 0.1765 Pa respectively.After bilateral middle turbinectomy,the maximum wall shear stress in the olfactory region of the left and right nasal cavity was 0.1543 Pa and 0.1055 Pa respectively.The maximum wall shear stress in the olfactory region of the left and right nasal cavity after the bilateral middle turbinate fracture was 0.1682 Pa and 0.1411 Pa.2.Characteristics of granule sedimentation before and after middle turbinate surgery:2.1 If the particle size is 10um and the density of inhaled particles changes(950、1250、1550、1850 kg/m~3)in the inspiratory phase and resting state(respiratory flow rate is 15L/min):The sedimentation rates of particles in the upper airway before operation were93.42%,96.54%,98.30%and 99.10%respectively.The upper airway particle sedimentation rates after partial turbinectomy were91.80%,94.96%,96.13%and 98.62%respectively.The particle sedimentation rate of upper airway after internal displacement of middle turbinate fracture was 93.19%,96.20%,98.34%and 98.76%respectively.2.2 When the particle density is 1550 kg/m~3and the particle size(particle size=1.0,2.5,4,7.5,10.0 um)changes,the particle deposition rate in the upper airway gradually increases after partial resection of bilateral middle turbinate and internal displacement of bilateral middle turbinate fracture,but the change is smaller than that before operation.2.3 When the particle density is 1550 kg/m~3and the particle size is 10um:The sedimentation rate of particles in the olfactory region before operation was0.867%,the grading sedimentation rate of the olfactory region in the middle turbinate side of the left and right nasal cavity was 10.390%and 18.181%,and the grading sedimentation rate of the olfactory region in the middle septal side of the left and right nasal cavity was 45.455%and 25.194%,respectively.After the operation of bilateral middle turbinate fracture,the particle sedimentation rate of olfactory region was 1.208%,the grading sedimentation rate of left and right nasal middle turbinate nasal olfactory region was 37.069%and 37.931%,and the grading sedimentation rate of left and right nasal septum olfactory region was 22.414%and 2.586%,respectively.After the operation of bilateral middle turbinate fracture,the particle sedimentation rate of olfactory region was 0.558%,the grading sedimentation rate of left and right nasal middle turbinate nasal olfactory region was 10.417%and 8.333%,and the grading sedimentation rate of left and right nasal septum olfactory region was 62.500%and18.750%.Conclusion:1.Through biomechanical research,it is found that the internal displacement and partial resection of middle turbinate fracture will change the airflow or particle sedimentation in the local anatomical change area,but have little impact on the overall airflow and particle sedimentation in the nasal cavity.The surgery for internal displacement of middle turbinate fractures increases the sedimentation rate of particles in the olfactory area on the side of the middle turbinate,which can improve nasal olfactory function.3.After partial middle turbinate resection,the graded sedimentation rate of particles in the nasal olfactory region is greater in the nasal septum side than in the middle turbinate side,and will damage the nasal olfactory function. |
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