Pre-surgery planning tool for estimation of resection volume to improve nasal breathing based on lattice Boltzmann fluid flow simulations

Computational analysis of human upper airway aerodynamics

There is a considerable interest in understanding transient human upper airway aerodynamics, especially in view of assessing the effects of various ventilation therapies. Experimental analyses in a patient-specific manner pose challenges as the upper airway consists of a narrow confined region with complex anatomy. Pressure measurements are feasible, but, for example, PIV experiments require special measures to accommodate for the light refraction by the model. Computational fluid dynamics can bridge the gap between limited experimental data and detailed flow features. This work aims to validate the use of combined lattice Boltzmann method and a large eddy scale model for simulating respiration, and to identify clinical features of the flow and show the clinical potential of the method. Airflow was computationally analyzed during a realistic, transient, breathing profile in an upper airway geometry ranging from nose to trachea, and the resulting pressure calculations were compared against in vitro experiments. Simulations were conducted on meshes containing about 1 billion cells to ensure accuracy and to capture intrinsic flow features. Airway pressures obtained from simulations and in vitro experiments are in good agreement both during inhalation and exhalation. High velocity pharyngeal and laryngeal jets and recirculation in the region of the olfactory cleft are observed. Graphical Abstract The Lattice-Boltzmann Method combined with Large Eddy Simulations was used to compute the aerodynamics in a human upper airway geometry. The left side of this graphical abstract shows the velocity and vorticity (middle figure in bottom row, and right figure of the right bottom figure) profiles at peak exhalation. The simulations were validated against experiments on a 3D-print of the geometry (shown in the top figures on the right hand side). The pressure drop (right bottom corner) shows a good agreement between experiments and simulations.

[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.