Numerical Investigation of the Flow Field in Realistic Nasal Septal Perforation Geometry

Faramarzi, Mohammad; Abouali, Omid; Atighechi, Saeid; Ahmadi, Goodarz; Farhadi, Pejman; Keshavarzian, Erfan; Behniafard, Nasim; Baradaranfar, Mohammad Hossein

doi:10.2500/ar.2014.5.0090

Cited by 15 publications

(18 citation statements)

References 30 publications

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“…In line with the changes in pressure drop post RME, we observed a decrease in the velocity of air ow at the expiratory phase in group 2. This trend was supported by the results of Faramarzi et al, who evaluated the aerodynamics of the nasal cavity in a patient with septal perforation and found that velocity was higher in the area that showed a higher pressure drop [28]. In our study, we failed to observe any statistically signi cant change in terms of maximum wall shear stress between either T0 and T1 or the two groups.…”

Section: Cfd Simulationsupporting

confidence: 89%

The Effect of Rapid Maxillary Expansion on the Upper Airway’s Aerodynamic Characteristics

Feng

Chen

Halme

et al. 2020

Preprint

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Background: The effect of rapid maxillary expansion (RME) on the upper airway (UA) has been studied earlier but without a consistent conclusion. This study aims to evaluate the outcome of RME on the upper airway function in terms of airflow resistance by applying a computational fluid dynamics (CFD) simulation.Methods: This retrospective cohort study consists of seventeen cases with two consecutive CBCT scans obtained before (T0) and after (T1) RME. Patients were divided into two groups with respect to patency of the nasopharyngeal airway as expressed in the adenoidal nasopharyngeal ratio (AN): group 1 was comprised of patients with an AN ratio < 0.6 and group 2 encompassing those with an AN ratio ≥ 0.6. CFD simulation at inspiration and expiration were performed based on the three - dimensional (3D) models of the UA segmented from the CBCT images. The aerodynamic characteristics in terms of pressure drop, midsagittal maximum velocity, and maximum wall shear stress were compared by independent samples t-test between the two groups at T0 and T1. Results: At T0, the pressure drop at expiration was significantly higher in group 2 compared to group 1, whereas the difference between the two groups was not significant at T1. The midsagittal maximum velocity of the two groups decreased to some extent at expiration, but without significant difference. The midsagittal maximum velocity of group 2 was at inspiration significantly higher than that of group 1 at T0 and T1. Conclusion: RME had a positive effect on UA airflow resistance in patients with an AN ratio ≥ 0.6. The findings provide positive evidence of RME in airway function and should thus be recommended to patients with both a narrow maxilla and enlarged adenoid.

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Section: Cfd Simulationsupporting

confidence: 89%

The Effect of Rapid Maxillary Expansion on the Upper Airway’s Aerodynamic Characteristics

Feng

Chen

Halme

et al. 2020

Preprint

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“…Computational fluid dynamics (CFD) has been used to analyze the characteristics of various nasal sinus conditions or procedures in efforts to better understand the associated effects on nasal airflow . However, there are relatively limited CFD data demonstrating the abnormal airflow patterns and the associated affects related to septal perforation in real patients; most prior published studies either use simulated perforations based on a healthy nose or have a sample size of 1 patient …”

mentioning

confidence: 99%

Computational fluid dynamics evaluation of posterior septectomy as a viable treatment option for large septal perforations

Otto

Farag

et al. 2017

Int Forum Allergy Rhinol

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Introduction Numerous surgical techniques exist to treat nasal septal perforation (NSP). The surgical closure of large NSPs (>2cm) is still challenging. Posterior septectomy has been reported as a simple alternative to treat large NSP, yet its mechanisms for symptom relief are not clear, and if failed, its consequence cannot be easily reversed. Methods Ten NSP patients were recruited: five underwent posterior septectomy and five conventional flap or button repair. Computational Fluid dynamics (CFD) simulated the nasal aerodynamics based on CT scans. All patients had preoperative CT, however, only four had postoperative CT – two underwent posterior septectomy and the other two flap repair. We examined surgical outcomes and the nasal airflow features among the two treatment options. Results Both groups of patients had good outcomes based on chart review. Patients undergoing septectomy had significantly larger perforation size (2.32±0.87 vs 1.21±0.60 cm), higher flow rate across the perforation (47.8±28.6 vs. 18.3±12.2 ml/s) and higher wall shear stress (WSS) along the posterior perforation margin (1.39±0.52 vs. 1.15±0.58 Pa). The posterior WSS significantly correlate with cross-over flow velocity (r=0.77, p=0.009) and was reduced by almost 67% post-septectomy, and by 29% post-repair. Conclusions This is the first CFD analysis on NSP patient cohort. NSP resulted in flow disturbance and increased WSS that potentially lead to symptomatology. The removal of high stress points along the posterior margin may explain why posterior septectomy can be an effective treatment option. Aerodynamic abnormalities, in addition to perforation size and location, could serve as basis for future treatment decisions.

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“…All as far as we are aware, they have looked only at the airflow inside the nasal cavity and not outside as in this study. Septum perforation was numerically assessed for pre-and post-operation condition 15 . Similar approach was also used by Nomura el al.…”

Section: Introductionmentioning

confidence: 99%

Nasal Internal and External Aerodynamics for Healthy and Blocked Cavities

Nayebossadri

Avital

Motallebi

et al. 2018

J. Mech. Med. Biol.

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Human nasal airflow in a healthy and partially blocked cavities is investigated using computational and experimental means. While previous studies focused on the flow inside the nasal cavity, this study also looks at the external air stream coming out of the nostrils. The aim is to investigate the airflow subject to partial blocking in the nasal cavity and assess the potential of using a flow visualization method to identify abnormal nasal geometry. Two methods of study are used: Computational Fluid Dynamics (CFD) and experiment based on Particle Image Velocimetry (PIV). Nasal cavity geometry is reconstructed from CT scans. The flow visualization Schileren method is also demonstrated. The computational results agree well with the previous results in terms of Nasal Resistance (NR) and character of the internal flow. Good agreement is also found in the external aerodynamics during expiration between the computational and experimental results. Several generic partial blockages are investigated to show changes in NR, turbulence energy and the air stream leaving the nostrils during expiration. Anterior blockages are found to have more profound effects on all these three aspects, but all show effects on the external air stream. A possible universal angle for the external air stream emitted by a healthy nasal cavity is discussed.

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Numerical Investigation of the Flow Field in Realistic Nasal Septal Perforation Geometry

Cited by 15 publications

References 30 publications

The Effect of Rapid Maxillary Expansion on the Upper Airway’s Aerodynamic Characteristics

The Effect of Rapid Maxillary Expansion on the Upper Airway’s Aerodynamic Characteristics

Computational fluid dynamics evaluation of posterior septectomy as a viable treatment option for large septal perforations

Nasal Internal and External Aerodynamics for Healthy and Blocked Cavities

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