Takahisa Yamamoto

Paper No.JP57

Paper No. JP56

Aerosol medicine exhalation through the nose (ETN) is one of promising and comprehensive treatment methods for Eosinophilic Chronic Rhinosinusitis (ECRS) with asthma. In this treatment, the patient inhales aerosol of inhaled corticosteroid (ICS) medicine from mouth using portable inhaler. Then a part of the aerosol still floats and remains in upper airway. When the patient exhales inhaled air through the nose, the aerosol is effectively transported on the walls of middle meatus and olfactory fissure. This study performed Computational Fluid Dynamics (CFD) analysis for the transport phenomena of aerosol medicine during exhalation period in order to evaluate the curative effect of ETN numerically. As a result of CFD analysis, ETN formed impinging flow toward upper wall of nasopharynx, subsequently complex swirl and circulation flow in the nasopharynx region. In addition, main flow of ETN passed upper region of nasal cavity. Such the tendencies affected on aerosol transport characteristics a part of aerosol particles moved into ethmoindal sinuses.

Nebulizer treatment has been used for nasal diseases such as paranasal sinusitis, hypertrophic rhinitis and inferior concha inflammation. The effectiveness of the nebulizer treatment has been confirmed from clinical view points until now. However there are a few researches that evaluate the effect of the nebulizer treatment quantitatively, i.e., how medicinal mist transports and deposits on inflammation areas of nasal wall. Some researchers calculated intranasal transport phenomena of medicinal droplets using Computed Fluid Dynamics (CFD). However these researches analyzed a few cases. The individual difference was left out of consideration even though there were different shapes of nasal cavities and different grade of medical conditions. This study constructs three-dimensional geometry model of nasal cavity using an actual patient's CT data. The case undergoes deviated nasal septum, hypertrophic rhinitis, chronic sinusitis and bloating inferior nasal concha tumentia. This study analyzes the characteristics of airflow and medicinal droplet, especially focuses on local deposition characteristics. As a result airflow velocity and pressure drop increase in the narrowing region caused by jet effect. Inlet angle and velocity of nebulizer treatment can easily control medicinal droplet transport characteristics. The circulatory flow is able to contribute advances medicinal droplet transportation in widespread area of intranasal.

Controlling postoperative course is serious problem in liver transplantation. The transplantation changes blood flow balance in the liver consequently causes on local and overall swellings (deformation) of the transplanted liver. In order to prevent such the diseases prediction method is required before the transplantation surgery. This study build analytical method for blood flow in portal vein; geometric model was made from patient's CT image data and performed Computational Fluid Dynamics (CFD) analysis of blood flow in the portal vein. As a result of analysis, it was confirmed that this method was able to predict actual blood flow balance in the portal vein because the tendencies of calculation and measurement results conformed each other. In addition, blood flow in the left lobe of the portal vein showed different flow characteristics compared with right lobe; eddies were proceeded in the left lobe. These results mentioned here lead us detail blood flow characteristics in the portal vein and contribute to elucidation of the vascular disease.

Obstructive Sleep Apnea Syndrome (OSAS) is one of nasal disorders. In order to develop effective treatment for OSAS it is needed to discuss and survey not only from medical but also engineering points of views. The purpose of this study is to get the knowledge about the OSAS from engineering standpoint. This study made a three-dimensional geometry model of the respiratory organ which includes nasal, pharynx and larynx by means of OSAS patient's CT data, and performed Computational Fluid Dynamics (CFD) analysis for breathing air flow characteristics in respiration process. As the results of the analysis, this study confirmed eddies were generated and transported in all over the respiratory organs. In addition this study made clear that inhalation and exhalation wall share stresses. There were high wall share stress areas on anterior wall in the inhalation process, on the contrary posterior wall in the exhalation process. These characteristics affect on the development mechanism of OSAS.