Nasal airflow of patient with septal deviation and allergy rhinitis

Comparison of microparticle transport and deposition in nasal cavity of three different age groups

Objective: The nasal cavity effectively captures the particles present in inhaled air, thereby preventing harmful and toxic pollutants from reaching the lungs. This filtering ability of the nasal cavity can be effectively utilized for targeted nasal drug delivery applications. This study aims to understand the particle deposition patterns in three age groups: neonate, infant, and adult.Materials and methods: The CT scans are built using MIMICS 21.0, followed by CATIA V6 to generate a patient-specific airway model. Fluid flow is simulated using ANSYS FLUENT 2021 R2. Spherical monodisperse microparticles ranging from 2 to 60 µm and a density of 1100 kg/m3 are simulated at steady-state and sedentary inspiration conditions.Results: The highest nasal valve depositions for the neonate are 25% for 20 µm, for infants, 10% for 50 µm, 15% for adults, and 15% for 15 µm. At mid nasal region, deposition of 15% for 20 µm is observed for infant and 8% for neonate and adult nasal cavities at a particle size of 10 and 20 µm, respectively. The highest particle deposition at the olfactory region is about 2.7% for the adult nasal cavity for 20 µm, and it is <1% for neonate and infant nasal cavities.Discussion and conclusions: The study of preferred nasal depositions during natural sedentary breathing conditions is utilized to determine the size that allows medication particles to be targeted to specific nose regions.

[Measurement of nasal septum area in 128 Chinese patients with nasal septum deviation]

Objective:Establish the anatomical parameters of the nasal septum and the area of each component in patients with nasal septum deviation, for the sake of guiding the scope of surgical resection for correction of nasal septum deviation. Methods:This is a retrospective study of 128 cases of sinus computer tomography images of patients with nasal septum deviation, marked 9 nasal septal anatomical locations, measured the area of the nasal septum and its components, and analyzed the trend of the percentage of the area of the nasal septum cartilage in the total area of the nasal septum with age. Results:The total area of the nasal septum in the 128 patients with nasal septum deviation is: （2951.96±305.91） mm², the area of nasal septal cartilage: （961.89±229.64） mm², the area of the vertical ethmoid plate: （1123.96±214.17） mm², the area of the vomerine: （652.77±108.09） mm². The area of male septum is larger than that of female. As age increases, the nasal septal cartilage gradually decreases, and the percentage of the nasal septal cartilage area in the total area of the nasal septum gradually decreases. Conclusion:Elderly people who undergo nasal septum correction should be carefully considered to grasp the scope of resection, and the influence of gender on the area of nasal septum should also be paid attention.

Nasal airflow comparison in neonates, infant and adult nasal cavities using computational fluid dynamics

BACKGROUND AND OBJECTIVE

Neonates are preferential nasal breathers up to 3 months of age. The nasal anatomy in neonates and infants is at developing stages whereas the adult nasal cavities are fully grown which implies that the study of airflow dynamics in the neonates and infants are significant. In the present study, the nasal airways of the neonate, infant and adult are anatomically compared and their airflow patterns are investigated.

METHODS

Computational Fluid Dynamics (CFD) approach is used to simulate the airflow in a neonate, an infant and an adult in sedentary breathing conditions. The healthy CT scans are segmented using MIMICS 21.0 (Materialise, Ann arbor, MI). The patient-specific 3D airway models are analyzed for low Reynolds number flow using ANSYS FLUENT 2020 R2. The applicability of the Grid Convergence Index (GCI) for polyhedral mesh adopted in this work is also verified.

RESULTS

This study shows that the inferior meatus of neonates accounted for only 15% of the total airflow. This was in contrast to the infants and adults who experienced 49 and 31% of airflow at the inferior meatus region. Superior meatus experienced 25% of total flow which is more than normal for the neonate. The highest velocity of 1.8, 2.6 and 3.7 m/s was observed at the nasal valve region for neonates, infants and adults, respectively. The anterior portion of the nasal cavity experienced maximum wall shear stress with average values of 0.48, 0.25 and 0.58 Pa for the neonates, infants and adults.

CONCLUSIONS

The neonates have an underdeveloped nasal cavity which significantly affects their airway distribution. The absence of inferior meatus in the neonates has limited the flow through the inferior regions and resulted in uneven flow distribution.