Factors Affecting Location of Nasal Airway Obstruction

A common cause of nasal airway obstruction (NAO) is nasal septum deviation (NSD). In clinical strategies, septoplasty has been one of the effective ways to resolve NAO. Current opinions on surgical removal of focal location and size remain inconclusive altogether. Studies on plethora demonstrated that pressure gradient (PG) or streamwise pressure gradient (SPG) are reliable predictors for the location or area of NAO. This study aims to investigate the physical quantities, i.e., pressure, vorticity and turbulent flow energy which are associated with NAO using computational fluid dynamics (CFD) and to provide aerodynamic characteristics of NAO in depth. Two patients were diagnosed with left-sided NSD using computed tomography (CT). The patient-specific three-dimensional (3D) nasal cavity model was reconstructed using Mimics 19.0 (Materialise, Belgium). We adopted the time-dependent k-ω model to predict the flow field. The transient Reynolds-Averaged Navier-Stokes equations were calculated using software COMSOL 5.5 (COMSOL Inc., Palo Alto, CA). The logistic regression method was implemented to evaluate the impact of the targeted physical quantities. The CFD results showed that the rotational flows and vortical flow structures emerged at the rear of the NAO site in the left nasal cavity. The magnitude of SPG, vorticity, and turbulent kinetic energy of the location of NAO was significantly larger than those of the contralesional side. Statistical analysis demonstrated that there was no statistical difference (p>0.05) among the vorticity, turbulent kinetic energy, and SPG. This study exhibits that the vorticity and turbulent kinetic energy (TKE) may also serve as effective aerodynamic markers for the prediction of NAO location besides PG and SPG. CFD with machine learning research assists physicians in handling nasal airway obstruction (NAO) patients' surgical sites in the future.