【abstract’s supplement 】Analysis of COD using CFD
Conductive olfactory dysfunction (COD) is caused by an obstruction in the nasal cavity and is characterized by changeable olfaction. COD can occur even when the olfactory cleft is anatomically normal, and therefore, the cause in these cases remains unclear. Herein, we used computational fluid dynamics to examine olfactory cleft airflow with a retrospective cohort study utilizing the cone beam computed tomography scan data of COD patients. By measuring nasal–nasopharynx pressure at maximum flow, we established a cut-off value ( in the supplementary experiment targeting 95 people with normal sense of smell ) at which nasal breathing can be differentiated from combined mouth breathing in COD patients (in the main experiment with 31 COD patients without nasal polyps ). We found that increased nasal resistance led to mouth breathing ( in the supplementary experiment ) and that the velocity and flow rate in the olfactory cleft at maximum flow were significantly reduced in COD patients with nasal breathing only compared to healthy olfactory subjects (in the main experiment ). In addition, we performed a detailed analysis of common morphological abnormalities associated with concha bullosa (in the main experiment ). Our study provides novel insights into the causes of COD, and therefore, it has important implications for surgical planning of COD, sleep apnea research, assessment of adenoid hyperplasia in children, and sports respiratory physiology.
In addition to the complicated research design, the strict character limit for submissions to other journals has made the abstract difficult to understand. This study involves two experiments. The main experiment was a retrospective study of COD patients. As a result, we obtained chaotic data for which no regularity could be found. So we became aware of the concept of mouth breathing and conducted supplementary experiments to eliminate possible data on combined mouth breathing.