RU2797190C1 - Method for assessing intranasal aerodynamics - Google Patents

Abstract

FIELD: medicine, otorhinolaryngology.

SUBSTANCE: anterior active rhinomanometry (PARM) in the right and left nasal passages separately is performed. Computed tomography (CT) is performed, during which images of the paranasal sinuses are obtained in the form of 2D images. Then 2D images are reconstructed in sagittal and coronal projections and a file is obtained with an image of the paranasal sinuses in the following three projections: coronal, sagittal and axial. After that, the resulting file is written to a DVD disc in the form of a DICOM file which is then converted first into a 3D image of the patient's head, then into a file with STL resolution, which is converted into a solid geometric three-dimensional 3D model of the upper respiratory tract. Then a 3D model of the movement of air flows in each nasal passage is built in the form of a graphic image in the coordinate system. In this case, the intensity of the air flow in each nasal passage is determined by the degree of coloring of its image from saturated blue, corresponding to a speed of 0 m/s, to red, corresponding to a speed of 5.0 m/s. When performing PARM, nasal flow velocity is measured during inhalation at a pressure of 150 Pa, and the DICOM file is converted from a sequence of 2D images into 3D images of the patient's head using the Invesalius program. An STL file containing a 3D image of the patient's head is converted into a 3D model of the upper respiratory tract using the Ansys Space С lame 2019 R3 program. Moreover, the resulting 3D model covers the nasal cavity, paranasal sinuses, nasopharynx, larynx and upper trachea. The construction of a 3D model of the movement of air flows is carried out in the inhalation mode in the Ansys Fluint 2019 R3 program. In this case, the values of the air flow velocity obtained during the PRM are used as boundary conditions. After that, coronal sections of a 3D model of the movement of air flows are made to visualize the color intensity of the air flow on each section of the resulting projection. It is additionally evaluated in the Ansys CDF-post 2019 R3 program according to the following criteria: ventilation symmetry of the right and left nasal passages, comparison of the identified zones with the highest and lowest ventilation in each nasal passage with the values of physiological norms, calculation of nasal flow velocity at a specific point. After that, based on the results of the assessment, either conservative or surgical treatment is prescribed.

EFFECT: method makes it possible to increase the efficiency of examining patients with difficulty in nasal breathing by identifying areas in the nasal cavity with impaired intranasal aerodynamics by building a personal 3D model of air flow in each nasal passage.

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Description

The invention relates to medicine, namely to otorhinolaryngology, and can be used in the examination of patients with difficulty in nasal breathing.

The nasal cavity is an anatomically and physiologically important aerodynamic environment, which is the first connector and distributor of air flow throughout the body.

However, various anatomical changes in the external nose and intranasal structures, as well as inflammatory changes in the mucous membrane of the nasal cavity, can significantly disrupt intranasal aerodynamics and lead to the development of a number of pathological processes.

The movement of the air flow and the implementation of the main respiratory function of the nose is of fundamental importance when examining patients with subjective nasal breathing disorders.

Currently, about ten main diagnostic methods are used to assess intranasal aerodynamics, each of which has its own advantages and disadvantages.

In recent years, a method for analyzing the circulation of air flow in the nasal cavity has appeared - computer computational aerodynamics. This diagnostic approach is based on computer simulation of the movement of the air flow relative to intranasal structures, obtained from complex calculations that do not accurately convey the real conditions of the state of the nasal mucosa in each individual patient to study the physiology of the nose.

A known method for diagnosing nasal breathing disorders, including the determination of nasal airflow variables calculated using computational fluid dynamics (see Giancarlo B. Cherobin, Richard L. Voegels J Eloisa M. M. S. Gebrim, Guilherme J. M. Garcia. ((Sensitivity of nasal airflow variables computed via computational fluid dynamics to the computed tomography segmentation threshold)) November 16, 2018. PLoS ONE, Sao Paulo, Brazil 13(11), p. 1-19).

The disadvantages of this method are:

- in computer simulation, the initial air flow is considered laminar at a bilateral flow rate of less than 20 l / min, however, this assumption does not allow an individual analysis of the air flow movement in each individual patient, since the flow movement is not laminar in everyone, but may be accompanied by severe turbulence;

- The measured nasal flow velocity and nasal resistance are only used for comparison with the results obtained from flow simulations.

The closest in technical essence to the claimed solution is a method for predicting changes in intranasal aerodynamics in patients after reconstructive maxillofacial surgery, containing computer analysis of the data obtained during the examination of the patient, which includes performing anterior active rhinomanometry of the PARM in the right and left nasal passages separately, and also computed tomography CT, during which images of the paranasal sinuses are obtained in the form of 2D images, then they are reconstructed in sagittal and coronal projections and a file is obtained with an image of the paranasal sinuses in three projections: coronal, sagittal and axial, after which the resulting file is recorded on DVD a disk in the form of a DICOM file, which is then converted first into a 3D image of the patient's head, then into a file with STL resolution, which is converted into a solid geometric 3D model of the upper respiratory tract, then a 3D model of the movement of air flows in each nasal passage is built in the form of a graphic images in the coordinate system, while determining the intensity of the air flow in each nasal passage according to the degree of coloring of its image from saturated blue, corresponding to a speed of 0 m/s, to red, corresponding to a speed of 5.0 m/s (see Fig. Yamagata K, Shinozuka K, Ogisawa S, Himejima A, Azaki H, Nishikubo S, Sato T., Suzuki M., Tanuma T., Tonogi M., “A preoperative predictive study of advantages of airway changes after maxillomandibular advancement surgery using computational fluid dynamics analysis)) PLoS ONE, Tokyo, Japan, 2021, 16(8), p. 1-19).

When implementing this method, before and after surgical treatment, anterior active rhinomanometry (hereinafter referred to as ARM) is performed with the measurement of nasal resistance in the right and left nasal passages separately.

Computed tomography (hereinafter referred to as CT) of the paranasal sinuses is performed. 2D images are reconstructed in sagittal and coronal projections using the software channel Intage Volume Editor (version 1.1; Cybernet Systems).

The resulting file is then recorded in DICOM (Digital Imaging and Communications in Medicine) format.

Next, the file is converted to a format with STL resolution ("Stereolithography"), with which a three-dimensional head model is saved for further use in the HEXPRESS program (version 7.2).

A computational grid is formed, covering the space from the nostrils to the nasal cavities and the respiratory tract of the pharynx to the epiglottis, and then a three-dimensional model of the air flow in the right and left nasal passages is built separately.

The disadvantages of this method are:

- CT of the paranasal sinuses, using a slice thickness of 1.0 mm, gives an image with insufficiently high image resolution and leads to significant errors in the creation of three-dimensional models;

- the movement of the air flow during inhalation was a simulation model built using software and taking into account that the patient is at rest at a constant value of atmospheric pressure, air viscosity and air temperature.

The technical result of the proposed solution is to increase the efficiency of examination of patients with difficulty in nasal breathing by identifying areas in the nasal cavity with impaired intranasal aerodynamics by building a personal 3D model of air flow in each nasal passage.

To achieve the specified technical result in the method for assessing intranasal aerodynamics, containing computer analysis of the data obtained during the examination of the patient, which includes performing anterior active rhinomanometry of the PARM in the right and left nasal passages separately, as well as CT computed tomography, during which images of the paranasal sinuses are obtained in the form of 2D images, then they are reconstructed in sagittal and coronal projections and a file is obtained with an image of the paranasal sinuses in three projections: coronal, sagittal and axial, after which the resulting file is recorded on a DVD disc as a DICOM file, which is then converted first to 3D image of the patient's head, then into a file with STL resolution, which is converted into a solid geometric three-dimensional model of the upper respiratory tract, then a 3D model of the movement of air flows in each nasal passage is built in the form of a graphic image in the coordinate system, while determining the intensity of the air flow in each nasal passage, according to the degree of coloring of its image, from saturated blue, corresponding to a speed of 0 m/s, to red, corresponding to a speed of 5.0 m/s, according to the invention, when performing PARM, the speed of the nasal flow is measured during inhalation at a pressure of 150 Pa , and the DICOM file is converted from a sequence of 2D images into 3D images of the patient's head using the Invesalius program, and the STL file containing the 3D image of the patient's head is converted into a 3D model of the upper respiratory tract using the Ansys Space Clame 2019 R3 program, and the resulting 3D model covers the nasal cavity, paranasal sinuses, nasopharynx, larynx and upper trachea, and the construction of a 3D model of the movement of air flows is carried out in the inspiratory mode in the Ansys Fluint 2019 R3 program, while the air flow velocity values obtained during PARM are used as boundary conditions, after what do the coronal sections of the 3D model do to visualize the color intensity of the air flow on each section of the resulting projection, which are additionally evaluated in the Ansys CDF-post 2019 R3 program according to the following criteria: ventilation symmetry of the right and left nasal passages; comparison of the identified zones with the highest and lowest ventilation in each nasal passage with the values of physiological norms; calculation of nasal flow velocity at a specific point; after which, based on the results of the assessment, conservative or surgical treatment is prescribed.

In the known solutions for building a 3D model of air flow for each patient, the same nasal flow velocity is set in all cases, which greatly smoothes the transmission of air flow in each nasal passage.

In the claimed solution, the combination of actions such as the presence of PARM indicators measured in a particular patient under real breathing conditions, and the use of the Ansys Space Clame 2019 R3 program when creating a 3D model of air flow allows to increase the reliability of assessing the degree of nasal breathing impairment.

This set allows you to create for each patient a personalized 3D model of the movement of air flows in each nasal passage, since aerodynamic indicators calculated under real conditions of physiological breathing in a sitting position for each nasal passage separately are used to simulate intranasal dynamics.

At the same time, the created virtual 3D model of the movement of air flows reflects the influence of the state of the mucous membrane of the nasal cavity on the circulation of air flows in the mode of real nasal breathing, which makes this model realistic and informative for understanding the aerodynamic processes occurring in the nasal cavity.

Additional construction of a 3D model of the movement of air flows in each nasal passage makes it possible to calculate the aerodynamic characteristics of nasal breathing at any given point in the created model.

This allows you to accurately identify areas with the best or impaired ventilation in order to understand the localization of the most functionally significant areas of intranasal aerodynamics disturbance and create a plan for correcting the identified violations.

From the foregoing, it follows that the introduced distinctive features affect the specified technical result, are in a causal relationship with it.

The method is illustrated by drawings, where:

- figure 1 shows table 1 with the classification of Mlynski G., Beule A., (2008) for calculating the degree of obstruction in one half of the nose with anterior active rhinomanometry;

- figure 2 shows a graph of the anterior active rhinomanometry PARM;

- figure 3 shows an image obtained by exporting a 2D surface to STL files in the Invisalius program with an image control panel, tools for segmentation and applying filters;

- figure 4 shows an image built in the Ansys Space Clame 2019 R program, showing the structure of the nasal cavity and paranasal sinuses, obtained by exporting a 3D model to stereolithography files (hereinafter referred to as STL);

- figure 5 shows a virtual model of the air flow in each nasal passage in the nasal cavity with the distribution of the modulus of the nasal flow velocity, set according to the PARM data for the right and left nasal passages, respectively, while sequentially built coronal sections illustrate changes in the nasal flow velocity depending on intranasal architectonics;

- figure 6 shows the stage of work in the Ansys Space Clame 2019 R3 program with a virtual 3D model, where uniform coronal sections of the model are made in the left rectangular coordinate system using the toolbar;

- figure 7 shows the stage of work in the Ansys Space Clame 2019 R3 program with a virtual 3D model of the movement of air flows in the right and left nasal passages, where isolines are shown illustrating the movement of air in symmetrical areas and using the toolbar at given points, the speed of movement is calculated air streams.

The method is carried out as follows.

Assessment of intranasal aerodynamics is performed in patients 18 years of age and older. Contraindications to this diagnostic method are:

- organic damage to the central nervous system with impaired cognitive and other functions;

- mental illness in the stage of decompensation;

- polypous process and other pathological processes leading to complete obstruction by a foreign body, tumor, etc., at least one of the common nasal passages.

The day before the examination, the patient is asked to refrain from using any nasal sprays (topical corticosteroids or intranasal antihistamines, decongestants and other drugs that have a decongestant effect), to avoid severe physical activity and visits to saunas and baths.

Stage 1. Video endoscopic examination of the nasal cavity.

After a conversation with the patient and the establishment of complaints about the violation of nasal breathing, a video endoscopic examination of the nasal cavity is performed.

The patient is in a sitting position. To visualize the structural features of the intranasal structures, a rigid endoscope with a viewing angle of 0 degrees and a diameter of 4.0 mm manufactured by Karl Storz is used.

First, an examination of the anterior part of the nasal cavity is performed, then the endoscope is advanced along the common nasal passage along the inferior turbinate to the choana, visualizing the floor of the nasal cavity, the inferior turbinate, its posterior end, the mouths of the auditory tubes, and the Rosemüller's fossa.

Then the endoscope is removed, oriented laterally upwards and anteriorly, the middle nasal concha, the place of its attachment, the area of the uncinate process, the semilunar fissure, the ethmoid vesicle are examined, and the study is completed by examining the upper nasal passage.

When evaluating the endoscopic picture, special attention is paid to the condition of the mucous membrane, the presence (absence) of crusts, secretions, as well as structural features of intranasal structures in general.

Thus, at stage 1, the following data are obtained: the presence of edema of the nasal mucosa in the patient; about hypertrophy of the lower and / or middle turbinates; about deformation of the nasal septum; about the discharge in the nasal cavity; about adenoid vegetations, about neoplasms in the nasal cavity and nasopharynx.

Stage 2. Performing anterior active rhinomanometry PARM.

Then PARM is performed, while in the right and left nasal passages, the nasal flow velocity during inspiration is measured separately at a pressure of 150 Pa using the RHINO-SYS rhinomanometric complex from Happersberger Otopront GmbH (Germany).

The hardware rhinomanometric complex Otopront "RHINO-SYS" is a complete system for diagnosing nasal breathing. It includes performing rhinomanometry, rhinoresistometry, acoustic rhinometry and long-term rhinometry (daily monitoring).

The indicated RHINO-SYS complex consists of the RHINO-BASE platform, a laptop computer, a portable RHINO-MOVE module for 24-hour rhinoflowmetry, and the RHINO-ACOUSTlC system for acoustic measurement of the nasal passages.

At the same time, the conditions for performing anterior active rhinomanometry PARM are observed, namely:

- the study is carried out in a room with a constant air temperature of 20-22 ° C in accordance with the recommendations of the European Committee for the Standardization of Rhinomanometric Methodology (2005);

- before the start of the study, the patient is offered to breathe calmly through the nose for 15 minutes in a sitting position.

During the study, a mask of the required size is used, equipped with a highly sensitive measurement sensor and a catheter, which is attached to a special adhesive nasal adapter connected to a pneumotachometer. A removable filter is placed between the mask and the measuring cap. The rhinomanometer is connected to a personal computer.

At the beginning of the study, the patient is placed in a sitting position, the left nostril is sealed with a special adapter connected by a silicone tube and the platform of the RHINO-SYS complex, and the patient is asked to perform calm breathing movements into the mask with the mouth closed.

With the help of the RHINO-BASE platform software, the PARM indicators are simultaneously calculated and recorded.

Among indicators PARM measure the speed of the nasal flow in the right common nasal passage at a pressure of 150 Pa.

Then, the adhesive nasal adapter is removed from the left nostril and the right half of the nose is hermetically obturated, and the patient is asked to perform calm breathing movements into the mask with the mouth closed, while registering similar PARM values for the left nasal passage.

All the indicators obtained using the RHINO-BASE platform are automatically entered into a table and the degree of nasal obstruction or the absence of nasal breathing disorders for each half of the nose separately is established in accordance with the classification of G. Mlynski, A. Beule, 2008 for PARM separately (Fig. .1).

With the help of the RHINO-BASE platform, the corresponding graphs of nasal flow versus pressure are built, characterizing each half of the nasal cavity separately.

Thus, in step 2, the following data are obtained: nasal flow velocity in the right and left nasal passages separately during inspiration.

Stage 3. Performing CT computed tomography on a Siemens SOMATON Emotion 16 tomograph and creating a 3D image of the patient's head.

Carry out the following steps.

Computed tomography of the paranasal sinuses is performed using scan parameters: 130kv, slice thickness 0.75 mm, pitch 0.8 and images of the paranasal sinuses are obtained in the form of 2 D images.

Next, 2D images are reconstructed in sagittal and coronal projections, according to the H70s sharpFR and H31s medium smooth+ reconstruction algorithm, and a file is obtained with an image of the paranasal sinuses in three projections: coronal, sagittal and axial.

The resulting file is then written to a DVD as a DICOM (Digital Imaging and Communications in Medicine) file.

After that, the specified DICOM file is loaded into the Invesalius program (designed to create and store three-dimensional reconstructions of medical images based on a sequence of 2D DICOM files).

From the sequence of 2D DICOM images, a 3D image of the patient's head is built.

Converting a DICOM file from a sequence of 2D images into 3D images of the patient's head in the Invesalius program allows you to build 3D images of the facial skeleton with high accuracy, highlight areas of interest, segment and visualize these areas.

Then, using the toolbar of the Invesalius program, edit this 3D image. To do this, perform zooming, panning, rotating the image, changing the brightness / contrast, segmenting and applying a filter.

The resulting 3D image of the patient's head is converted into a file with STL ("Stereolithography") resolution, with which a three-dimensional head model is saved for further use in the Ansys Space Clame 2019 R3 program.

Thus, in step 3, a 3D image of the patient's head is obtained, converted into a file with STL resolution.

Stage 4. Converting the 3D image of the patient's head into a 3D model of the upper respiratory tract.

An STL file containing a 3D image of the patient's head is loaded into Ansys Space Clame 2019 R3. From a single STL surface, separate surfaces are formed.

Using the toolbar of the Ansys Space Clame 2019 R3 program, they check the nodes, filter the 3D image of the patient's head, model the shape of the calculated surface, build irregular volumetric difference meshes with 3 million volumetric tetrahedral elements, leaving only the nasal cavity with an entrance for the air flow through the nostrils, in fact nasal cavity, paranasal sinuses, nasopharynx with a transition to the larynx and further to the level of the upper trachea.

As a result of these transformations, an STL file with a 3D image of the patient's head is converted into a 3D model of the upper respiratory tract, covering the nasal cavity, paranasal sinuses, nasopharynx, larynx, and upper trachea.

Thus, in step 4, the following data are obtained: a solid geometric 3D model of the upper respiratory tract, covering the nasal cavity, paranasal sinuses, nasopharynx, larynx and upper trachea.

Stage 5. Building a 3D model of the movement of air flows.

Then, a solid-state geometric 3D model of the upper respiratory tract is converted and a stationary air flow is modeled in each nasal passage in the inhalation mode in the Ansys Fluint 2019 R3 program.

At the same time, to simulate the movement of air flows in each nasal passage, the values of the air flow velocity during inhalation are used as boundary conditions, which are recorded when performing PRM in the right and left nasal passages at a pressure level of 150 Pa.

After that, the main geometric characteristics of the computational domain are checked.

The calculations use the left rectangular coordinate system, in which the Z axis is directed from the inlet perpendicular to the coronal sections, and the Y axis is vertical.

Based on the calculations performed in the above coordinate system, a 3D model of the movement of air flows starting from the vestibule of the nose (nostrils) and ending at the level of the nasopharynx is built.

This model is presented as a graphic image that can be moved in a coordinate system in 3 planes and calculate the speed of the nasal flow at any given point.

According to the 3D model of the movement of air flows, the flow velocities are judged by the color intensity of the flow from saturated blue, corresponding to practically a speed of 0 m/s, to red, corresponding to 5.0 m/s.

Thus, at stage 5, the following data are obtained: the computational domain is built in the coordinate system and a 3D model of the movement of air flows is built.

Stage 6. Visualization of air flow in the nasal cavity.

Further, with the obtained 3D model of the movement of air flows, they work in the left rectangular coordinate system and, using the toolbar, make uniform coronal sections of the model to visualize the color intensity of the air flow on each slice of the resulting projection.

Stage 7. Evaluation of the 3D model of the movement of air flows.

The obtained coronal sections of the virtual 3D model are analyzed in the Ansys CDF-post 2019 R3 program according to the following criteria:

- symmetry of ventilation of the right and left nasal passages;

- identification of zones with maximum and minimum ventilation in each nasal passage according to the degree of color intensity of the air flow image;

- comparison of the identified zones with maximum and minimum ventilation in each nasal passage with the values of physiological norms;

- calculation of the nasal flow rate using the toolbar of the Ansys CDF-post 2019 R3 program in the areas of interest;

- conducting an analysis in accordance with the identified violations and creating a plan for the correction of intranasal structures to restore aerodynamics.

Based on the results of the analysis, zones with a decrease in flow velocity are identified in each nasal passage and compared with the existing changes in the intranasal structures established during endoscopy of the nasal cavity, while the maximum nasal flow velocity when creating a 3D model of air flow is taken as 5.0 m/s. s corresponding to the red area.

Based on the results of the assessment, conservative or surgical treatment is prescribed.

The method is illustrated by the following example.

Patient B., 61 years old, applied to the St. Petersburg Research Institute of Ear, Throat, Nose and Speech with complaints of periodic nasal congestion.

Stage 1. Video endoscopic examination of the nasal cavity.

Anamnesis of the disease: violation of nasal breathing notes for a long time. Under the control of an endoscope with a viewing angle of 0 degrees, with a diameter of 4.0 mm, the nasal cavity was examined: the nasal mucosa is pale pink, moderately edematous. The inferior turbinates are moderately edematous, large, the inferior turbinates are partially contractible with anemia.

The nasal septum is curved to the left in the bone and cartilage sections throughout. The right middle nasal concha on the right is enlarged in size, the left middle nasal concha is of normal size, the middle nasal passages are free. There is no discharge in the nasal cavity. In the nasopharynx there is a moderate amount of clear mucous discharge. The mucous membrane of the posterior wall and fornix of the nasopharynx is pink, granular, the fornix of the nasopharynx is free. The tubal ridges are of normal size, the pharyngeal openings of the auditory tubes are free on both sides.

Stage 2. Implementation of PARM.

Then, after a 15-minute rest in a sitting position, anterior active rhinomanometry of the PARM is performed using the RHlNO-SYS complex from Happersberger Otopront GmbH (Germany).

In the left nasal passage at a pressure of 150 Pa, the nasal flow rate is set to 374 ml/s (range 300-500 ml/s), which corresponds to a mild degree of nasal breathing disorder (figure 2).

Analysis of similar aerodynamic characteristics showed in the right nasal passage the presence of a moderate degree of obstruction, namely, according to the classification presented in figure 1, the nasal flow rate was equal to 222.0 ml/s (range 180 - 300 ml/s).

Stage 3. CT scan and creation of a 3D image of the patient's head.

The patient then underwent a CT scan of the paranasal sinuses using scan parameters: 130kv, slice thickness 0.75 mm, pitch 0.8.

Next, images were reconstructed in the sagittal and coronal projections according to the H70s sharpFR and H31s medium smooth+ reconstruction algorithms.

The resulting file was recorded on a DVD disc as a DICOM file and loaded into the Invesalius program.

In this program, a 3D model of the patient's head was built, after which it was converted into a file with STL resolution (figure 3).

Stage 4. Converting the 3D image of the patient's head into a 3D model of the upper respiratory tract.

The resulting file was loaded into the Ansys Space Clame 2019 R3 program, the shape of the computational domain was modeled, and irregular volume difference grids were built.

Next, a solid 3D model of the upper respiratory tract was obtained, covering the nasal cavity, paranasal sinuses, nasopharynx, larynx and upper trachea (figure 4).

Stage 5. Building a 3D model of the movement of air flows.

Then, boundary conditions were set in the Ansys Fluint 2019 R3 program: the nasal flow rate was 374.0 ml/s in the left nasal passage, in the right - 222.0 ml/s, and the distribution of air flows in each nasal passage was modeled, obtaining 3D models of the movement of air flows (figure 5).

Stage 6. Visualization of air flow in the nasal cavity.

Further, in the left rectangular coordinate system, uniform coronal sections of the model were performed (Fig.6).

Stage 7. Evaluation of the 3D model of the movement of air flows.

Then, in the Ansys CDF-post 2019 R3 program, using a 3D model of air flow movement, a different degree of color intensity of the air flow (from blue to red) was established in the right and left nasal passages on all sections, starting from the first, that is, the emerging nasal air flows this patient is asymmetrical.

On the first two sections, the highest nasal flow velocity in the left nasal passage is established, the air flow is colored mainly in yellow and red.

On similar sections, the air flow in the right nasal passage has a predominantly yellow tint with single increases in the flow velocity to red areas.

Starting from the third coronal section, a significant change in the intensity of color towards enhancement was established almost throughout the entire length up to the maximum values (red color) of the flow image in the right nasal passage.

In the left passage, on the contrary, a decrease in color intensity to blue-green hues was found in the projection of the lower nasal passage.

On subsequent sections, reflecting the deep sections of the nasal cavity, in both nasal passages there is a decrease in the intensity of the color of the nasal flows in symmetrical areas, however, the greatest decrease in ventilation was recorded in the right half of the nose at the level of the lower nasal passage, which indicates a non-physiological distribution of the circulating nasal flow.

In the left nasal passage, the distribution of the intensity of the air flow circulation falls mainly on the middle and lower nasal passages in the deep sections, which corresponds to the parameters of the distribution of the physiological nasal flow.

In the nasopharynx, the distribution of air flows is also uneven.

The calculation in the Ansys CDF-post program of the average nasal flow velocity on the first two coronal sections showed an average flow velocity in the left nasal passage of 1.5 m/s, in the right nasal passage in the symmetrical section of 0.75 m/s, which is significantly lower.

On the third section, the average speed of the nasal flow in the left nasal passage in the projection of the lower nasal passage was 1.0 m/s, in the projection of the middle nasal passage the latter reached 3.0 m/s.

In the right nasal passage, a symmetrical distribution of the nasal flow was noted with an average speed of 2.25 m/s.

On subsequent sections at the level of the middle parts of the nasal cavity, the speeds of nasal flows in both halves of the nose are distributed evenly with a symmetrical decrease in flow speeds of 1.5 to 0.75 m/s.

A significant decrease in airflow velocity was found in the right half of the nasal cavity in the projection of the average stroke (airflow velocity up to 1.3 m/s, compared with the left half of the nose, where the airflow velocity is 1.5 m/s).

Further, an uneven distribution of air flow velocities in the nasopharynx was established, where the velocities ranged from 1.1 m/s to 2.8 m/s.

When comparing the obtained visual image of the ventilation of the left nasal passage with the data of video endoscopy of the nasal cavity, it was revealed that the cause of the asymmetry of air flows and a decrease in the flow velocity in the left nasal passage is not only the presence of a curvature of the nasal septum to the left in the lower third of the cartilaginous section of the nasal septum throughout.

The performed analysis of the distribution of flows in each half of the nose and the calculation of the flow velocities in symmetrical sections made it possible to establish the effect of the increased size of the right middle turbinate on the decrease in the speed of the circulation of the air flow in the right half of the nasal cavity to 1.3 m/s.

An assessment of changes in the aerodynamic characteristics of the nasal flow in the left nasal passage showed the presence of a local zone of nasal flow velocity reduction in the middle sections of the nasal cavity at the level of the lower nasal passage. This is due to the symmetrical increase in the posterior ends of the inferior turbinates.

At the same time, the uneven distribution of air flows in the nasopharynx is primarily due to the presence of barriers to adequate ventilation, both from the right and from the left nasal passage.

The construction of a 3D model of the movement of air flows showed that in the process of nasal obstruction formation in this patient, not only the curvature of the nasal septum plays a role, but also hypertrophy of the right middle turbinate, as well as hypertrophied posterior ends of the inferior turbinates.

To restore the physiological parameters of intranasal aerodynamics, a planned surgical treatment is required in this patient, aimed at normalizing the function of nasal breathing in volume: correction of the nasal septum, resection of the lateral portion of the middle turbinate, partial conchotomy of the posterior ends of the inferior turbinates with lateroposition of the latter.

The proposed method has the following advantages:

- Reliably and accurately illustrates intranasal aerodynamics;

- allows you to measure the speed of the nasal flow at any point to understand the norm or pathology;

- reflects the circulation of air flows in the nasal cavity with the maximum approximation to the real conditions of nasal breathing;

- allows you to create a personal 3D model of the movement of air flows through the use of individual CT data of the sinuses and flow rates measured in a patient during PARM.

Claims (5)

1. A method for assessing intranasal aerodynamics, containing computer analysis of data obtained during examination of a patient, which includes performing anterior active rhinomanometry of the PARM in the right and left nasal passages separately, as well as computed tomography CT, during which images of the paranasal sinuses are obtained in the form of 2D images , then they are reconstructed in sagittal and coronal projections and a file is obtained with an image of the paranasal sinuses in three projections: coronal, sagittal and axial, after which the resulting file is written to a DVD disc as a DICOM file, which is then converted first into a 3D image of the patient's head, then - into a file with STL resolution, which is converted into a solid geometric three-dimensional 3D model of the upper respiratory tract, then a 3D model of the movement of air flows in each nasal passage is built in the form of a graphic image in the coordinate system, while determining the intensity of the air flow in each nasal passage along the degree of coloration of its image from saturated blue, corresponding to a speed of 0 m/s, to red, corresponding to a speed of 5.0 m/s, characterized in that when performing PARM, the speed of the nasal flow is measured during inhalation at a pressure of 150 Pa, and the conversion a DICOM file from a sequence of 2D images into 3D images of the patient's head is produced in the Invesalius program, and an STL file containing a 3D image of the patient's head is converted into a 3D model of the upper respiratory tract using the Ansys Space Clame 2019 R3 program, and the resulting 3D model covers the nasal cavity , paranasal sinuses, nasopharynx, larynx and upper trachea, and the construction of a 3D model of the movement of air flows is carried out in the inspiratory mode in the Ansys Fluint 2019 R3 program, while the air flow velocity values obtained during PARM are used as boundary conditions, after which coronary slices of a 3D model of air flow to visualize the color intensity of the air flow on each slice of the resulting projection, which are additionally evaluated in the Ansys CDF-post 2019 R3 program according to the following criteria: ventilation symmetry of the right and left nasal passages; comparison of the identified zones with the highest and lowest ventilation in each nasal passage with the values of physiological norms; calculation of nasal flow velocity at a specific point; after which, based on the results of the assessment, conservative or surgical treatment is prescribed. 2. The method according to p. 1, characterized in that prior to performing the PARM, a video endoscopic examination of the nasal cavity is performed. 3. The method according to p. 1, characterized in that when performing PARM, the patient is in a sitting position. 4. The method according to p. 1, characterized in that when performing CT scanning parameters are used: 130 kV, slice thickness 0.75 mm, pitch 0.8. 5. The method according to claim 1, characterized in that when creating a 3D model of the movement of air flows in the calculations, a left rectangular coordinate system is used, in which the Z axis is directed from the inlet perpendicular to the coronal sections, and the Y axis is vertical.

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