Introduction
Many patients have nasal obstruction in rhinology disease. For the evaluation of nasal obstruction, rhinomanometry is very popular worldwide.1 Rhinomanometry can measure nasal pressure and airflow during inspiration and expiration. Additionally, it can measure nasal resistance to measure the pressure difference between the nostril and choana. Nasal resistance can be affected by alternating congestion and decongestion of the nasal mucosa, which is termed the nasal cycle.2, 3 Lang et al. investigated the nasal cycle using endoscopy, rhinoresistometry, and acoustic rhinometry.4 Gogniashvili et al. also investigated the nasal cycle in the same manner.5 In general anesthesia, nasal patency is investigated before nasal intubation.6 Rhinomanometry can measure nasal resistance during the nasal cycle; however, it cannot measure the direct airflow pressure in the nasal cavity.
Recently, computational fluid dynamics (CFD) in rhinology has been popular for measuring airflow or pressure.7, 8 This enables the observation of the airflow, pressure, heat, and streamline, which cannot be determined directly. Kim et al. reviewed patient-specific CFD models of nasal airflow.9Moreover, Wang et al. simulated applying CFD to the study of the nasal cavity in 2005.10 In turn, Xiong et al. reported a numerical flow simulation in virtual post-endoscopic sinus surgery.11 Twenty-two healthy adults were studied to determine the normal nasal airflow.12 It was found that nasal resistance affected nasal obstruction. Recently, these phenomena were simulated using CFD. Radulesco reported a comparison of nasal obstruction with CFD variables.13 Finally, Berger reported the agreement between rhinomanometry and CFD regarding nasal resistance.14
CFD can be achieved by creating a 3D model and using numerical simulation. However, the nose is composed of the nasal cavity and paranasal sinus and is a very complicated structure. Thus, it is very difficult to create a highly accurate nasal cavity and paranasal sinus 3D model. The recent literature includes many CFD rhinology documents, with absence of accurate nose 3D models. Therefore, we created a nose 3D model to check the all-natural ostium of all paranasal sinuses. It was unclear whether the simulation in reality reflected the human body. By comparing the real nasal resistance value, which can be measured, with the numerical simulation value, it is possible to judge whether or not it is closer to the human body.