Impact of a Concha Bullosa on Nasal Airflow Characteristics in the Setting of Nasal Septal Deviation: A Computational Fluid Dynamics Analysis

Alterations in nasal airflow and air conditioning after endoscopic nasopharyngectomy for recurrent nasopharyngeal carcinoma: a pilot computational fluid dynamics study

Endoscopic nasopharyngectomy represents a significant intervention for recurrent nasopharyngeal carcinoma (NPC). Various surgical techniques, including transnasal and transoral approaches, are employed. However, the impact of these procedures on nasal airflow dynamics is not well understood. This computational fluid dynamics (CFD) study aimed to investigate alterations in nasal airflow and air conditioning following endoscopic nasopharyngectomy. A 55-year-old male patient with recurrent NPC was selected, whose CT data were utilized for image reconstruction. A preoperative model and two postoperative models, including the transnasal and transoral approach models, were established. The airflow patterns and various CFD parameters were analyzed. In the postoperative models, the high-speed airflow went along the soft palate and into the nasopharyngeal outlet, and there was the low-speed turbulence in the expanded nasopharyngeal cavity. Compared to the preoperative model, the postoperative models exhibited reductions in surface-to-volume ratio, nasal resistance, airflow velocity and proportion of high wall shear stress regions in nasopharynx. The changing trends of nasopharyngeal air temperature and humidity in the preoperative and transoral models were consistent. The heating and humidification efficiency decreased in the transnasal model compared to the transoral model. The endoscopic nasopharyngectomy for recurrent NPC affects the nasal airflow and warming and humidification function. The transoral approach has less influence on aerodynamics of the upper airway compared to the transnasal approach. From a CFD perspective, the endoscopic nasopharyngectomy does not increase the risk of postoperative complications, including the empty nose syndrome and the carotid blowout syndrome.

The anatomical variations of paranasal sinuses may be related to the formation of antrochoanal polyp by computed tomography imaging study

Background

There is little investigation into the connection between anatomic variations and the development of antrochoanal polyp (ACP), and the etiology of ACP remains unclear. The study aims to explore the relationship among anatomic variations, maxillary sinus volume, nasal meatus-related parameters, and the occurrence of ACP.

Methods

There were 127 patients included in this retrospective cross-sectional study with unilateral ACPs hospitalized at Shandong Provincial ENT Hospital between February 2010 and February 2020. Evaluation indicators included anatomic variations, maxillary sinus volume, and nasal meatus-related parameters in 45 children and 82 adults, which were evaluated twice by 3DSlicer software. Parameters were assessed using the Kolmogorov-Smirnov test, followed by paired t-test and Chi-squared test for multiple comparisons.

Results

Significant differences were found in the accessory maxillary ostium (AMO) and maxillary sinus retention cyst between two sides (both P<0.001). Maxillary sinus volume and sex had an association of statistical significance on adults' ACP side (P=0.026) and non-antrochoanal polyp (non-ACP) side (P=0.032). The affected side's maxillary sinus volume was significantly larger than the healthy side (P<0.001). The length from the maxillary sinus orifice to the plane of the most lateral margin of the middle turbinate of the ACP side was larger than the non-ACP side in children (P=0.044). Males' length from the maxillary sinus orifice to the plane of the most lateral margin of the middle turbinate of the ACP side was considerably greater than the healthy side (P<0.001). The length from the maxillary sinus orifice to the plane of the most lateral margin of the middle turbinate (P=0.014) and the length from the inferior turbinate to the nasal septum (P=0.013) on the non-ACP side was higher than the affected side in adults. Males' length from the inferior turbinate to the nasal septum was higher on the healthy side than the affected side (P<0.001). Males had a greater maximum length from the maxillary sinus lateral wall to the nasal septum (P=0.024) and the length from the inferior turbinate to the nasal septum (P=0.003) on the non-ACP side than females. Males had a larger maximum length from the maxillary sinus lateral wall to the nasal septum on the ACP side than females (P=0.011).

Conclusions

In our study, the occurrence of the AMO, the maxillary sinus's expanded size, and the stenosis of the associated channels around the ostiomeatal complex and common meatus are regarded as probably connected to the formation of ACPs. In addition, the anatomic variations that involve the ostiomeatal complex and may lead to a change in maxillary sinus pressure and nasal ventilation are important factors in the formation of ACPs.

Anatomical Variations Associated With Maxillary Sinus Fungal Ball

OBJECTIVE

We investigated the anatomical and dental factors associated with unilateral maxillary sinus fungal ball (MSFB). Also, we evaluated the effect of combinations of those factors on the incidence of MSFB.

METHODS

Three hundred patients were divided into MSFB, normal, and chronic rhinosinusitis (CRS) groups. We reviewed paranasal computed tomography scans for the presence of deviated nasal septum, concha bullosa (CB), Haller cells, and various dental factors. Also, we measured the ethmoid infundibulum, maxillary natural ostium, and CB.

RESULTS

Maxillary sinus fungal ball showed a more significant association with CB compared to the other 2 groups (37%, P < .05). The MSFB group had a lower rate of Haller cells than the normal group (10% vs 22%, respectively; P < .05). Also, the MSFB group had a wider maxillary sinus ostium than the normal group (7.07 ± 1.8 vs 5.48 ± 1.3 mm; P < .01). Moreover, the combination of CB and Haller cells was significantly associated with a decreased rate of the fungal ball (P = .047, odds ratio = 0.694). The dental factors were more prevalent in the MSFB and CRS groups (73% and 75%, respectively) than in the normal group (32%, P < .001).

CONCLUSIONS

Maxillary sinus fungal ball is significantly associated with CB, Haller cells, an increased maxillary sinus ostium size, and dental factors.

Clinical Efficacy Analysis of Functional Rhinoplasty Assisted by Nasal Endoscopy

OBJECTIVE

To analyze the clinical effect of endoscopy-assisted functional rhinoplasty.

METHODS

Endoscopy-assisted functional rhinoplasty was performed in all patients. Deviated nasal septum was corrected, nasal septum cartilage graft was prepared through open access under the assistance of endoscopy, the nasal frame structure was adjusted with the endoscopy-assisted rhinoplasty combined with middle and inferior turbinoplasty, and the patient's nasal ventilation function and external nose cosmetology were restored. Visual Analogue Scale (VAS), Nasal Obstruction Symptom Evaluation (NOSE), nasal acoustic reflex, and nasal resistance were examined preoperatively and 6 months postoperatively. Rhinoplasty Outcome Evaluation (ROE), nasal appearance deviation value, and morphological measurement of the external nose were used to assess the external nasal appearance. Finally, postoperative satisfaction was used for overall evaluation.

RESULTS

In terms of nasal ventilation evaluation, the VAS and NOSE scores of nasal obstruction decreased significantly at 6 months after the operation compared with that before the operation (1.96 ± 0.84 vs 6.68 ± 1.28, 4.25 ± 1.80 vs 12.25 ± 2.50; P < .05). Among the objective indexes, MCA1, MCA2 and NV5 were significantly increased whereas RT, MCA1a/MCA1b, MCA2a/MCA2b, MD1a/MD1b, and MD2a/MD2b were significantly decreased compared with those before the operation (P < .05). The MD1 and MD2 levels before and after operation had no significant differences (P > .05). In the evaluation of external nose morphology, postoperative ROE was significantly increased, and the deviation value of nasal appearance was significantly decreased [(16.93 ± 2.61 vs 10.64 ± 3.01), (1.46 ± 1.11 mm vs 5.72 ± 2.30 mm), P < .05]. In terms of postoperative patient satisfaction: 26 cases (92.9%) were very satisfied with nasal ventilation function, 2 cases (7.1%) were satisfied with nasal ventilation function, 24 cases (85.7%) were very satisfied with nasal appearance, and 4 cases (14.3%) were satisfied with nasal appearance.

CONCLUSIONS

Nasal endoscopy-assisted functional rhinoplasty can improve the nasal ventilation function and external nasal morphology at the same time. Moreover, its clinical effect is good, and the patient satisfaction is high.

[Correlation between nasal mucosal temperature change and nasal airflow perception]

The mechanism of nasal airflow perception remains little known. It is currently believed that the main mechanism for perceiving nasal patency is to activate transient receptor potential melastatin subtype 8. Computer fluent dynamics show that increased airflow and heat flux are associated with higher subjective scores. Similarly, physical measurements of the nasal cavity using a temperature probe show a correlation between the lower nasal mucosa temperature and better results. Trigeminal function detection also indirectly confirms this. This literature review aimed to explore the role of nasal mucosal temperature change in the subjective perception of nasal patency and the secondary aim was to appraise the relevant evidence about the mechanism.

Evaluation of nasal function after endoscopic endonasal surgery for pituitary adenoma: a computational fluid dynamics study

OBJECTIVE

To analyze the effect of different endoscopic endonasal approaches (EEAs) on nasal airflow and heating and humidification in patients with pituitary adenoma (PA) by computational fluid dynamics (CFD).

METHODS

A three-dimensional pre-surgical model (Pre) of the nasal cavity and 6 that were post-EEA surgery were created from computed tomography scans as follows: small posterior septectomy (0.5 cm, sPS), middle posterior septectomy (1.5 cm, mPS), large posterior septectomy (2.5 cm, lPS), and sPS with middle turbinate resection (sPS-MTR), mPS-MTR, and lPS-MTR. Simulations were performed by CFD to compare the changes in different models.

RESULTS

The temperature in the nasal vestibule rose more rapidly than in other parts of the nasal cavities in all models. There were no apparent differences in temperature and humidity among the models in sections anterior to the middle turbinate head (C6 section). MTR significantly influenced airflow distribution between the bilateral nasal cavities and the different parts of the nasal cavity, while changes in temperature and humidity in each section were mainly affected by MTR. The temperature and humidity of the choana and nasopharynx of each postoperative model were significantly different from those of the preoperative model and the change in values significantly correlated with the surface-to-volume ratio (SVR) of the airway.

CONCLUSIONS

Changes due to the different nasal structures caused different effects on nasal function following the use of EEA surgery for the treatment of PA. CFD provided a new approach to assess nasal function, promising to provide patients with individualized preoperative functional assessment and surgical planning.

[Advances in etiology and mechanism of structural nasal obstruction]

Structural nasal obstruction（SNO） is a series of diseases caused by congenital or acquired structural anatomical abnormalities of nasal airway and its surrounding tissues, which leads to increased nasal ventilation resistance. The effect of medication drugs for SNO is poor and surgical intervention is often needed. However, the abnormal structure of nasal airway is very complex, including the periphery of nasal airway, internal nasal airway, the front and rear of nasal airway and complex factors. These abnormal structures may interfere with the nasal airflow mechanics by changing the nasal ventilation volume and disrupting the symmetry of the bilateral nasal cavity, and finally lead to subjective feeling of nasal obstruction. In addition, the structure of nasal airway has plasticity. After the abnormal structure appears, the corresponding compensation of nasal airway can occur to ensure normal nasal ventilation and bilateral nasal cavity symmetry. Therefore, the SNO is the result of the failure of nasal airway remodeling after the appearance of abnormal structures. The etiology of SNO is complex, involving original structural abnormalities, nasal symmetry changing and nasal airway structure remodeling. Therefore, accurate identification of the main factors leading to SNO is the vitalpremise of making personalized nasal ventilation surgery.

Aerodynamics Analysis of the Impact of Nasal Surgery on Patients with Obstructive Sleep Apnea and Nasal Obstruction

OBJECTIVE

The purpose of this study was to evaluate the effects of nasal surgery on airflow characteristics in patients with obstructive sleep apnea (OSA) by comparing the alterations of airflow characteristics within the nasal and palatopharyngeal cavities.

METHODS

Thirty patients with OSA and nasal obstruction who underwent nasal surgery were enrolled. A pre- and postoperative 3-dimensional model was constructed, and alterations of airflow characteristics were assessed using the method of computational fluid dynamics. The other subjective and objective clinical indices were also assessed.

RESULTS

By comparison with the preoperative value, all postoperative subjective symptoms statistically improved (p < 0.05), while the Apnea-Hypopnea Index (AHI) changed little (p = 0.492); the postoperative airflow velocity and pressure in both nasal and palatopharyngeal cavities, nasal and palatopharyngeal pressure differences, and total upper airway resistance statistically decreased (all p < 0.01). A significant difference was derived for correlation between the alteration of simulation metrics with subjective improvements (p < 0.05), except with the AHI (p > 0.05).

CONCLUSION

Nasal surgery can decrease the total resistance of the upper airway and increase the nasal airflow volume and subjective sleep quality in patients with OSA and nasal obstruction. The altered airflow characteristics might contribute to the postoperative reduction of pharyngeal collapse in a subset of OSA patients.

Nasal airflow of patient with septal deviation and allergy rhinitis

A numerical simulation of a patient’s nasal airflow was developed via computational fluid dynamics. Accordingly, computerized tomography scans of a patient with septal deviation and allergic rhinitis were obtained. The three-dimensional (3D) nasal model was designed using InVesalius 3.0, which was then imported to (computer aided 3D interactive application) CATIA V5 for modification, and finally to analysis system (ANSYS) flow oriented logistics upgrade for enterprise networks (FLUENT) to obtain the numerical solution. The velocity contours of the cross-sectional area were analyzed on four main surfaces: the vestibule, nasal valve, middle turbinate, and nasopharynx. The pressure and velocity characteristics were assessed at both laminar and turbulent mass flow rates for both the standardized and the patient’s model nasal cavity. The developed model of the patient is approximately half the size of the standardized model; hence, its velocity was approximately two times more than that of the standardized model.

Numerical Simulation of Nasal Airflow Aerodynamics, and Warming and Humidification in Models of Clival Chordoma Pre and Post-Endoscopic Endonasal Surgery

OBJECTIVES

To study the effect of endoscopic endonasal surgery on nasal function for the treatment of clival chordoma.

METHODS

Pre and post-operative computed tomography (CT) scans of a case of chordoma treated with an endoscopic endonasal approach (EEA) were collected retrospectively, and models of the nasal cavity were reconstructed so that a subsequent numerical simulation of nasal airflow characteristics, warming, and humidification could be conducted.

RESULTS

Middle turbinectomy resulted in redistribution of airflow within the nasal cavity, and the most significant changes occurred in the middle section. Consistent with the results of airflow evaluation, it was found that the change in nasal anatomical structure significantly reduced warming and humidification. Nasal humidification decreased substantially when postoperative loss of mucosa was taken into consideration. The H₂O mass fraction of pharynx in inspiration phase were significantly correlated with airway surface-to-volume ratio (SVR).

CONCLUSIONS

The EEA for chordoma significantly affected nasal function. Attention should be paid to the protection of nasal structure and the associated mucosa.

Rapid Maxillary Expansion Has a Beneficial Effect on the Ventilation in Children With Nasal Septal Deviation: A Computational Fluid Dynamics Study

Nasal septal deviation (NSD) is one of the most common nasal diseases. Different from common clinical examination methods, computational fluid dynamics (CFD) can provide visual flow information of the nasal cavity. The dimension and volume of the nasal cavity are easily affected by rapid maxillary expansion (RME). The purpose of this study was to use CFD to evaluate the effect of RME on the aerodynamics of the nasal cavity in children with maxillary transverse deficiency and NSD. Computational fluid dynamics was implemented after 3D reconstruction based on the CBCT of 15 children who have completed RME treatment. After treatment, the volume increases in the nasal cavity, nasopharynx, oropharynx, and pharynx were not statistically significant. The wall shear stress of the nasal cavity after RME, 1.749 ± 0.673 Pa, was significantly lower than that before RME, 2.684 ± 0.919 Pa. Meanwhile, the maximal negative pressure in the pharyngeal airway during inspiration was smaller after RME (-31.058 Pa) than before (-48.204 Pa). This study suggests that RME has a beneficial effect on nasal ventilation. The nasal airflow became more symmetrical in the bilateral nasal cavity after RME. Pharyngeal resistance decreased with the reduction in nasal resistance and the increase in the volume of oropharynx after RME.