Method for simulating upper airway obstruction operation scheme based on airflow dynamics

Abstract

The invention belongs to the field of upper airway obstruction surgery, and particularly relates to a method for simulating an upper airway obstruction surgery plan based on computational fluid mechanics, which is used for checking and diagnosing anatomical abnormality of an upper airway of a patient, and relates to multi-part diseases. The method comprises the following steps: firstly, processing a CT scanning image to construct an original three-dimensional model; thirdly, dividing a three-dimensional grid, performing airflow simulation by using computational fluid mechanics software, and judging an airflow blocking part and degree according to a simulation result so as to determine a part aiming at the operation; performing digital simulation engraving on the part to obtain a postoperative model; finally, the airflow field is repeatedly simulated in the postoperative model, an ideal scheme is selected by comparing airflow field values, by simulating the airflow fields before and after the operation, doctors can accurately determine the targeted part of the operation, different operation schemes are simulated, and individualization and refinement of the operation are improved; the symptoms of a patient are improved most ideally, and the risk of postoperative complications is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of upper airway obstruction surgery, and specifically relates to a method for simulating an upper airway obstruction surgery plan based on aerodynamics. Background Art

[0002] Upper airway obstruction is one of the most common reasons for patients to visit an otolaryngology clinic. Before performing surgery, airway assessment is required to confirm the anatomical abnormalities of the upper airway. Currently, commonly used preoperative assessment methods include: nasal endoscopy, imaging examination, and traditional nasal ventilation function examination (such as rhinometry). However, these methods cannot specifically analyze the influence of the internal nasal anatomical structure on air flow resistance, nor can they dynamically and intuitively reflect the changes in the nasal air flow field.

[0003] Surgeons usually plan surgery only based on their experience and the assessment of patients, which results in the fact that for some patients, the nasal congestion symptoms are not improved ideally after surgery, or "empty nose syndrome" is caused by excessive resection of the nasal turbinates.

[0004] Therefore, it is necessary to research and develop a method that can intuitively and quantitatively reflect the precise anatomical sites causing air flow obstruction, as well as the improvement of the air flow field by different surgical methods. Thus, it can help clinicians predict the surgical effect through virtual surgery before performing real surgery, perform targeted operations on the obstruction sites, and enable patients to obtain ideal postoperative effects.

[0005] For this reason, the present invention provides a method for simulating an upper airway obstruction surgery plan based on aerodynamics. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art and solve at least one of the technical problems proposed in the background art.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: A method for simulating an upper airway obstruction surgery plan based on aerodynamics according to the present invention includes the following steps:

[0008] S1. Patient data collection and determination of upper airway anatomical structure abnormalities, to determine patients who need to undergo upper airway-related surgery and have upper airway anatomical structure abnormalities;

[0009] S2. Construction of a three-dimensional upper airway model, to obtain high-resolution two-dimensional images of the patient's upper airway through CT scanning, and based on the two-dimensional upper airway images, construct a three-dimensional upper airway model through a reconstruction method;

[0010] S3. Simulation of the air flow field of the original model, to simulate the air flow field on the three-dimensional model of the patient's original upper airway obtained in step S2;

[0011] S4: Simulate surgical implementation. Based on the original three-dimensional model, for the blocked part, use digital carving method to simulate multiple surgical plans and obtain the three-dimensional model of the upper airway after simulation of the operation.

[0012] S5: Simulate the airflow field after the operation. On the three-dimensional model after the simulated operation, simulate the airflow field according to the same method and conditions as in S3.

[0013] S6: Evaluate and optimize the surgical plan. Judge the improvement of the upper airway flow field by interpreting the cloud map. If it does not reach the ideal, return to step S4 to redesign the surgical plan until the best plan is determined. The doctor can thereby predict the improvement degree of the patient's postoperative obstruction symptoms.

[0014] Preferably, the upper airway anatomical structure abnormalities in step S1 include:

[0015] Anatomical abnormalities of the nasal cavity: nasal septum deviation, turbinate hypertrophy, nasal polyps, nasal passage stenosis, congenital nasal atresia, nasal bone fracture, nasal tumors;

[0016] Anatomical abnormalities of the pharynx: tonsil hypertrophy, adenoid hypertrophy, soft palate relaxation, uvula elongation or thickening, pharyngeal cavity stenosis, tumors of the tissues around the pharynx;

[0017] Anatomical abnormalities of the larynx: laryngeal tumors, laryngeal cleft, laryngeal stenosis, laryngeal cartilage dysplasia.

[0018] Preferably, step S2 specifically includes the following steps:

[0019] S201: Set the threshold range to -1240HU to -420HU for threshold segmentation to distinguish the upper airway tissue from the cavity.

[0020] S202: Erase the mask at the anterior naris to distinguish the upper airway from the external air, and erase the mask at the glottis to distinguish the upper airway from the lower respiratory tract.

[0021] S203: Calculate and obtain the three-dimensional model of the stl format of the patient's original upper airway.

[0022] Step S3 specifically includes the following steps:

[0023] S301: Preparation before model import and mesh generation: Open the preprocessing module ICEMCFD software in ANSYS software, import the model in stl format into this software, and make basic preparations for the subsequent mesh generation operation.

[0024] S302: Mesh generation: Use the finite volume method to generate meshes for the imported model in ICEMCFD software; during the meshing process, strictly control the number of meshes so that it is between 2×10 5 ~3×10 5Within a certain range, finally complete the establishment of the computational fluid dynamics (CFD) model and save it as a mesh model in MSH format;

[0025] S303. Import the mesh model into Fluent software: Import the mesh model that has been divided and saved in MSH format in S2 into Fluent software for subsequent simulation settings and calculations in Fluent;

[0026] S304. Set boundary conditions and physical parameters: Set boundary conditions in Fluent software. For the inhalation state, set the anterior naris as the inlet and the glottis as the outlet; for the exhalation state, it is the opposite, with the inlet being the glottis and the outlet being the anterior naris; apply a gas pressure of 50 Pa at the inlet, define the average velocity of the outlet plane as 5 m / s, and set the wall as a rigid no-slip boundary; in addition, set the density of air as 1.225 kg / m 3 and the viscosity coefficient as 1.8×10 -5 Pa·s;

[0027] S305. Numerical simulation calculation: Select the lattice Boltzmann method in Fluent software to perform numerical simulation calculations on the airflow field inside the CFD model; obtain relevant numerical values of the upper airway flow field through calculations, specifically including information such as flow velocity, airflow trace distribution, wall shear force, and pressure;

[0028] S306. Data visualization and result application: Import the data calculated by Fluent into CFDpost software for visualizing the calculation results; intercept the plane of interest and use the software to generate flow velocity contour maps, airflow trace distribution contour maps, and pressure contour maps; physicians can determine the exact location and degree of upper airway obstruction by reading these contour maps, and for the determined obstruction site, subsequent simulated surgeries can be performed.

[0029] Preferably, step S4 specifically includes the following steps:

[0030] S401. Determine the obstruction site determined in step S3;

[0031] S402. Based on the stl format of the patient's original upper airway three-dimensional model obtained in step S2;

[0032] S403. Import the three-dimensional model in stl format into the digital sculpting software NomadSculpt to simulate the proposed surgical plan; modify the geometric shape of the three-dimensional model by adding or deleting air or solid materials. The surgical plan includes complete or partial resection, correction, shaping, implantation, displacement, repair of anatomical abnormal parts, a combination of one or more of them;

[0033] S404. Obtain a three-dimensional upper airway model after simulated surgery through simulation.

[0034] Preferably, step S6 specifically includes the following steps:

[0035] S601. Interpret the velocity cloud map, air flow trace cloud map, and pressure cloud map to determine whether the upper airway flow field has been improved, and further determine whether the virtual surgery plan designed in step S4 has improved the upper airway obstruction;

[0036] S602. If the location and method of the virtual surgery fail to improve the upper airway flow field to an ideal state, return to step S4 to redesign the surgery plan and perform virtual surgery;

[0037] S603. Repeat step S2 until the air flow field after virtual surgery reaches a satisfactory state to determine the optimal surgery plan;

[0038] S604. The clinician predicts the degree of improvement of the upper airway obstruction symptoms after surgery based on the determined optimal surgery plan.

[0039] The beneficial effects of the present invention are as follows:

[0040] 1. A method for simulating an upper airway obstruction surgery plan based on aerodynamics, by simulating the original upper airway flow field, accurately determines the location and degree of upper airway obstruction, providing an accurate basis for formulating subsequent surgery plans.

[0041] 2. A method for simulating an upper airway obstruction surgery plan based on aerodynamics, based on the original three-dimensional model, can directly simulate surgical operations on the three-dimensional model using digital carving methods, such as various combination methods of resection, correction, shaping, implantation, displacement, repair, etc., providing an intuitive preview perspective for the clinician before performing the surgery.

[0042] 3. A method for simulating an upper airway obstruction surgery plan based on aerodynamics, by comparing the air flow field cloud maps of the model after simulation and the original model, can predict the degree of improvement of the obstruction symptoms of the patient after surgery, providing a basis for predicting the surgical effect.

[0043] 4. A method for simulating an upper airway obstruction surgery plan based on aerodynamics can compare the effects of different surgery plans on improving the air flow field, providing a basis for the selection of surgery plans.

[0044] In summary, for the method of simulating the surgical plan for upper airway obstruction based on aerodynamic dynamics according to the present invention, through the simulation of the airflow field, doctors can identify the blocked site and perform virtual surgery on this site. Through CFD technology, the postoperative airflow field can be simulated to analyze the effects of each surgical action in advance, ensuring the maximum benefit for patients with the least surgical invasion. This will improve the surgical outcome, postoperative morbidity, surgical time, and overall patient comfort. It will enhance the refinement and individualization of surgical planning, help doctors predict the benefits of surgery for patients, and reduce the risk of postoperative complications. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] Figure 1 is the principle block diagram in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] In order to make the technical means, creative features, achieved objectives, and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0048] As Figure 1 shown, a method of simulating the surgical plan for upper airway obstruction based on aerodynamic dynamics according to an embodiment of the present invention includes the following steps:

[0049] S1. Patient data collection and determination of upper airway anatomical structure abnormalities, to identify patients who need upper airway-related surgery and have upper airway anatomical structure abnormalities;

[0050] S2. Construction of the three-dimensional model of the upper airway, obtaining high-resolution two-dimensional images of the patient's upper airway through CT scanning, and constructing a three-dimensional model of the upper airway based on the two-dimensional images of the upper airway through a reconstruction method;

[0051] S3. Simulation of the airflow field of the original model, simulating the airflow field on the three-dimensional model of the patient's original upper airway obtained in step S2;

[0052] S4: Simulation of surgical implementation, based on the original three-dimensional model, for the blocked site, using digital carving methods to simulate multiple surgical plans to obtain a three-dimensional model of the upper airway after simulated surgery;

[0053] S5: Simulation of the airflow field after simulated surgery, simulating the airflow field on the three-dimensional model after simulated surgery according to the same method and conditions as in S3;

[0054] S6. Evaluation and optimization of the surgical plan, judging the improvement of the upper airway airflow field by interpreting the cloud map. If it does not meet the ideal, return to step S4 to redesign the surgical plan until the best plan is determined, and doctors can thereby predict the improvement degree of the patient's postoperative obstruction symptoms.

[0055] The upper airway anatomical abnormalities in step S1 include:

[0056] Nasal cavity anatomical abnormalities: nasal septum deviation, turbinate hypertrophy, nasal polyps, nasal passage stenosis, congenital nasal atresia, nasal bone fracture, nasal tumors;

[0057] Pharyngeal anatomical abnormalities: tonsil hypertrophy, adenoid hypertrophy, soft palate relaxation, uvula elongation or thickening, pharyngeal cavity stenosis, tumors of the tissues around the pharynx;

[0058] Laryngeal anatomical abnormalities: laryngeal tumors, laryngeal cleft, laryngeal stenosis, laryngeal cartilage dysplasia.

[0059] Step S2 specifically includes the following steps:

[0060] S201. Set the threshold range to -1240 HU to -420 HU for threshold segmentation to distinguish the upper airway tissue from the cavity;

[0061] S202. Erase the mask at the anterior nares to distinguish the upper airway from the external air, and erase the mask at the glottis to distinguish the upper airway from the lower respiratory tract;

[0062] S203. Calculate and obtain the three-dimensional model of the patient's original upper airway in stl format.

[0063] Step S3 specifically includes the following steps:

[0064] S301. Preparation before model import and mesh generation: Open the preprocessing module ICEMCFD software in ANSYS software, import the stl format model into this software, and make basic preparations for subsequent mesh generation operations;

[0065] S302. Mesh generation: Use the finite volume method to generate meshes for the imported model in ICEMCFD software; during the generation process, strictly control the number of meshes so that it is within the range of 2×10 5 ~3×10 5 to complete the establishment of the computational fluid dynamics (CFD) model and save it as a mesh model in MSH format;

[0066] S303. Import the mesh model into Fluent software: Import the mesh model that has been segmented and saved in MSH format in S2 into Fluent software for subsequent simulation settings and calculations in Fluent;

[0067] S304, boundary conditions and physical parameter settings: Boundary conditions were set in Fluent software. For the inhalation state, the anterior nares were set as the inlet and the glottis as the outlet. For the exhalation state, the inlet was the glottis and the outlet was the anterior nares. A gas pressure of 50 Pa was applied at the inlet, the average velocity of the outlet plane was defined as 5 m / s, and the wall was set as a rigid no-slip boundary. In addition, the density of the air was set to 1.225 kg / m 3 , the viscosity coefficient is 1.8×10 -5 Pa·s;

[0068] S305, numerical simulation calculation: select the lattice Boltzmann method in the Fluent software to perform numerical simulation calculation on the airflow field inside the CFD model; obtain relevant values ​​of the upper airway flow field through calculation, including flow velocity, airflow trace distribution, wall shear force, pressure and other information;

[0069] S306. Data visualization and result application: Import the data calculated by Fluent into CFDpost software to visualize the calculation results; intercept the plane of interest and use the software to generate flow velocity cloud map, airflow trajectory distribution cloud map, and pressure cloud map; doctors can determine the precise location and degree of upper airway obstruction by reading these cloud maps, and perform simulated surgery for the determined obstruction site.

[0070] Step S4 specifically includes the following steps:

[0071] S401, determining the blocked part determined in step S3;

[0072] S402, based on the original upper airway three-dimensional model of the patient in stl format obtained in step S2;

[0073] S403, importing the 3D model in stl format into the digital sculpting software NomadSculpt, simulating the proposed surgical plan; modifying the geometric shape of the 3D model by adding or removing air or solid materials, the surgical plan including complete or partial resection, correction, shaping, implantation, displacement, repair of the anatomical abnormal part, or a combination of one or more thereof;

[0074] S404, obtaining a three-dimensional upper airway model after the simulated surgery through simulation.

[0075] Step S6 specifically includes the following steps:

[0076] S601, reading the flow velocity cloud map, the airflow trace cloud map and the pressure cloud map to determine whether the upper airway flow field is improved, and then determining whether the virtual surgical plan designed in step S4 improves the upper airway obstruction;

[0077] S602. If the site and method of the virtual surgery fail to improve the upper airway airflow field to an ideal state, return to step S4, redesign the surgical plan and perform the virtual surgery again.

[0078] S603. Repeat step S2 until the airflow field after the virtual surgery reaches a satisfactory state, and determine the optimal surgical plan.

[0079] S604. Based on the determined optimal surgical plan, the clinician predicts the improvement degree of the upper airway obstruction symptoms after the surgery for the patient.

[0080] Embodiment

[0081] I. This embodiment aims at patients with upper airway obstruction caused by nasal septum deviation combined with inferior turbinate hypertrophy, resulting in moderate obstructive sleep apnea (OSA). Through aerodynamic simulation, a suitable surgical plan is designed and verified to improve the upper airway ventilation condition of the patient.

[0082] II. Specific implementation steps

[0083] (I) Patient data collection and preprocessing

[0084] Case selection: A 42-year-old male patient was selected. He was diagnosed with moderate OSA through polysomnography, with an apnea-hypopnea index (AHI) of 22.6. The patient complained of persistent nasal congestion symptoms. After examination, it was determined that the patient had anatomical abnormalities, manifested as a C-shaped deviation of the nasal septum to the left, with a deviation angle of 18° ± 2°, and bilateral inferior turbinate hypertrophy, with a thickness greater than 5 mm.

[0085] Image acquisition: The patient was scanned using a Siemens 64-slice spiral CT scanner in Germany. The scanning range was set from the nasal apex to the glottis, with a scanning slice thickness of 1 mm, an interslice spacing of 0.6 mm, a voltage of 120 kV, a current of 200 mA, an image matrix of 512×512, and the acquired file format was DICOM.

[0086] Three-dimensional model reconstruction and optimization: With the help of Mimics 22.0 software, by setting the threshold segmentation range from -1240 HU to -420 HU to distinguish the upper airway structure and air. The nasal septum deviation area (Locus1: located 3.2 cm from the anterior naris) and the inferior turbinate hypertrophy area (Locus2: at the entrance of the inferior meatus) were accurately outlined, and finally a three-dimensional model in STL format was output.

[0087] (II) Computational fluid dynamics (CFD) simulation

[0088] Mesh generation: ANSYS ICEM CFD 2021 R2 software was used for mesh generation to construct an unstructured mesh model. The mesh elements used tetrahedral elements, and the final total number of meshes generated was 2.8×105 pieces, and the output format is in MSH format.

[0089] Boundary condition setting: In the inhalation state, the anterior nares are set as the inlet and the glottis is set as the outlet; in the exhalation state, it is the opposite, the inlet becomes the glottis and the outlet becomes the anterior nares.

[0090] Apply a gas pressure of 50 Pa at the inlet, and define the average velocity of the outlet plane as 5 m / s. Set the wall as a rigid no-slip boundary, and at the same time set the density of air as 1.225 kg / m 3 , and the viscosity coefficient as 1.8×10 -5 Pa·s.

[0091] Numerical simulation calculation: Use the lattice Boltzmann method in Fluent software to carry out numerical simulation calculation on the airflow field inside the constructed CFD model, and obtain relevant data such as the flow velocity of the upper airway flow field, the distribution of airflow trace lines, the wall shear force, and the pressure.

[0092] Data visualization: Import the data calculated by Fluent into CFDpost software, intercept the planes where Locus1 and Locus2 are located, and both of these cross-sections are perpendicular to the main airflow trace lines, so as to generate the flow velocity contour map, the airflow trace line distribution contour map, and the pressure contour map for intuitive analysis of the flow field characteristics.

[0093] Result analysis: It is concluded through analysis that the average velocity at Locus1 is 2.03 m / s and the pressure is 41.91 Pa; the average velocity at Locus2 is 2.33 m / s and the pressure is 39.80 Pa. At the same time, it is found that there is no effective airflow trace line passing through the inferior meatus, and the distribution of airflow trace lines in the bilateral nasal cavities is asymmetric, indicating that there is an obvious obstruction in the patient's upper airway.

[0094] (3) Virtual surgery design and verification

[0095] Surgical plan design: Design two surgical plans. Plan A is simple septoplasty; Plan B is septoplasty combined with partial resection of the posterior ends of bilateral inferior turbinates.

[0096] Digital carving operation: Use NomadSculpt 3.5 software for digital carving. For the nasal septum, use the "voxel cutting" tool to remove the deviated part; for the inferior turbinate, use the "smooth carving" tool to reduce its volume by 30%.

[0097] CFD after simulated surgery: After simulated surgery with Scenario A, the average flow velocity at Locus1 increased to 2.24 m / s and the pressure dropped to 38.25 Pa; the average flow velocity at Locus2 became 2.40 m / s and the pressure became 36.55 Pa. After simulated surgery with Scenario B, the average flow velocity at Locus1 further increased to 2.35 m / s and the pressure dropped to 37.41 Pa; the average flow velocity at Locus2 reached 2.59 m / s and the pressure dropped to 34.72 Pa.

[0098] Scheme determination: By comparing the data after simulated surgery of the two schemes, it was found that the parameters of Scheme B were closer to the values of the upper airway airflow field without anatomical abnormalities. Therefore, Scheme B was selected as the final surgical scheme.

[0099] III. Summary of the embodiment

[0100] In this embodiment, through a series of steps such as patient data collection and preprocessing, computational fluid dynamics simulation, virtual surgery design and verification, based on the airflow dynamics simulation, a suitable surgical scheme was successfully determined for patients with upper airway obstruction caused by deviated nasal septum combined with hypertrophic inferior turbinate, providing a scientific and reliable reference basis for the formulation of clinical surgical schemes, helping to improve the surgical treatment effect and the upper airway ventilation function of patients.

[0101] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for simulating upper airway obstruction surgical plan based on airflow dynamics, characterized in that: The following steps are involved: S1. Patient data collection and upper airway anatomical abnormality determination, to identify patients who need upper airway-related surgery and have upper airway anatomical abnormalities; S2, constructing a three-dimensional model of the upper airway, obtaining a high-resolution two-dimensional image of the upper airway of the patient by means of CT scanning, and constructing a three-dimensional model of the upper airway based on the two-dimensional image of the upper airway by means of a reconstruction method; S3, original model airflow field simulation, simulating the airflow field on the original upper airway three-dimensional model of the patient obtained in step S2; S4: simulated surgery implementation, based on the original 3D model, using digital carving methods to simulate multiple surgical plans for the obstruction site, and obtain a simulated postoperative upper airway 3D model; S5: Simulation of postoperative airflow field: on the simulated postoperative three-dimensional model, the airflow field was simulated according to the same method and conditions as S3; S6, surgical plan evaluation and optimization, by interpreting the cloud map to determine the improvement of the upper airway flow field. If it is not ideal, return to step S4 to redesign the surgical plan until the best plan is determined. The doctor can use this to predict the degree of improvement of the patient's postoperative obstruction symptoms.

2. The method for simulating upper airway obstruction surgery based on airflow dynamics according to claim 1, characterized in that: The upper airway anatomical abnormalities in step S1 include: Abnormal nasal anatomy: deviated nasal septum, hypertrophic turbinate, nasal polyps, nasal stenosis, congenital nasal atresia, nasal bone fracture, nasal tumor; Pharyngeal anatomical abnormalities: enlarged tonsils, enlarged adenoids, loose soft palate, long or thick uvula, stenosis of the pharyngeal cavity, tumors of the tissues surrounding the pharynx; Laryngeal anatomical abnormalities: laryngeal tumors, laryngeal clefts, laryngeal stenosis, and laryngeal cartilage dysplasia.

3. A method for simulating upper airway obstruction surgery based on airflow dynamics according to claim 2, characterized in that: The step S2 specifically includes the following steps: S201, the threshold range is set to -1240HU to -420HU for threshold segmentation to distinguish the upper airway tissue from the cavity; S202, erasing the mask at the anterior nares to distinguish the upper airway from the outside air, and erasing the mask at the glottis to distinguish the upper airway from the lower airway; S203, calculating and obtaining the original upper airway three-dimensional model of the patient in STL format.

4. The method for simulating upper airway obstruction surgery based on airflow dynamics according to claim 3, characterized in that: The step S3 specifically includes the following steps: S301, model import and meshing preparation: open the pre-processing module ICEMCFD software in ANSYS software, import the model in stl format into the software, and make basic preparations for subsequent meshing operations; S302. Meshing: Use the finite volume method in the ICEMCFD software to mesh the imported model. During the meshing process, strictly control the number of grids to 2×10 5 ~3×10 5 Within the scope of , the computational fluid dynamics model is finally established and saved as a grid model in MSH format; S303, importing the mesh model into Fluent software: importing the mesh model divided in S2 and saved in MSH format into Fluent software, so as to perform subsequent simulation settings and calculations in Fluent; S304, boundary conditions and physical parameter settings: Boundary conditions were set in Fluent software. For the inhalation state, the anterior nares were set as the inlet and the glottis as the outlet. For the exhalation state, the inlet was the glottis and the outlet was the anterior nares. A gas pressure of 50 Pa was applied at the inlet, the average velocity of the outlet plane was defined as 5 m / s, and the wall was set as a rigid no-slip boundary. In addition, the density of the air was set to 1.225 kg / m 3 , the viscosity coefficient is 1.8×10 -5 Pa·s; S305, numerical simulation calculation: select the lattice Boltzmann method in the Fluent software to perform numerical simulation calculation on the airflow field inside the CFD model; obtain relevant values ​​of the upper airway flow field through calculation, including flow velocity, airflow trace distribution, wall shear force, pressure and other information; S306. Data visualization and result application: Import the data calculated by Fluent into CFDpost software to visualize the calculation results; intercept the plane of interest and use the software to generate flow velocity cloud map, airflow trajectory distribution cloud map, and pressure cloud map; doctors can determine the precise location and degree of upper airway obstruction by reading these cloud maps, and perform simulated surgery for the determined obstruction site.

5. The method for simulating upper airway obstruction surgery based on airflow dynamics according to claim 4, characterized in that: The step S4 specifically includes the following steps: S401, determining the blocked part determined in step S3; S402, based on the original upper airway three-dimensional model of the patient in stl format obtained in step S2; S403, importing the 3D model in stl format into the digital sculpting software NomadSculpt, simulating the proposed surgical plan; modifying the geometric shape of the 3D model by adding or removing air or solid materials, the surgical plan including complete or partial resection, correction, shaping, implantation, displacement, repair of the anatomical abnormal part, or a combination of one or more thereof; S404, obtaining a three-dimensional upper airway model after the simulated surgery through simulation.

6. The method for simulating upper airway obstruction surgery based on airflow dynamics according to claim 4, characterized in that: The step S6 specifically includes the following steps: S601, reading the flow velocity cloud map, the airflow trace cloud map and the pressure cloud map to determine whether the upper airway flow field is improved, and then determining whether the virtual surgical plan designed in step S4 improves the upper airway obstruction; S602: If the location and method of the virtual surgery fail to improve the upper airway airflow field to an ideal state, return to step S4, redesign the surgery plan and perform the virtual surgery; S603, repeating step S2 until the airflow field after the virtual surgery reaches a satisfactory state, and determining the best surgical plan; S604. The clinical physician predicts the degree of improvement of the patient's upper airway obstruction symptoms after surgery based on the determined optimal surgical plan.

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