[Study on changes of nasal resistance based on 3D printing transparent nasal cavity models]

Objective:To investigate the causal relationship between the minimum cross-sectional area of nasal cavity and nasal resistance. Methods:Thirty transparent detachable 3D printing nasal cavity models were made. The airway was completely blocked with sealing material at different anatomical sections. Then ventilatable nasal drainage tubes with different cross-sectional areas were used to pass through the nasal cavity. Nasal resistance was measured. SPSS was used for statistical analysis. Results:①The postoperative nasal resistances of patients and 3D printing nasal cavity models were （0.38±0.15）Pa· s/mL and （0.39±0.02）Pa· s/mL respectively. There was no statistical difference between the two groups.The preoperative nasal resistance of patients was （0.56±0.09）Pa· s/mL, and the postoperative nasal resistance of the models was significantly descreased by 31% compared with preoperative nasal resistance of the patients, with statistically significant difference（P<0.05）. ②When the ventilatable nasal drainage tubes with a cross-sectional area of 3.14 square millimeters was located in the the upper part of common meatus and the nasal valve area, the nasal cavity is moderately blocked, and the nasal resistances were （1.80±0.30） times and （2.02±0.36） times of that before the obstruction respectively. When the ventilatable nasal drainage tube was located in the lower part of common meatus,the nasal resistance was （1.68±0.28） times of that before the obstruction. ③When the ventilatable nasal drainage tubes with a cross-sectional area of 6.28 square millimeters and were located in the lower part of common meatus, the upper part of common meatus and nasal valve area, the nasal resistances were （1.44±0.23） times, （1.50±0.25） times and （1.60±0.27） times of those before obstruction, respectively. ④When the ventilatable nasal drainage tubes with a cross-sectional area of 9.42 square millimeters were located in the above areas, nasal ventilation was nearly normal without obvious nasal obstruction. The nasal resistances were （1.17±0.18） times, （1.26±0.21） times and （1.33±0.24） times of those before obstruction, respectively. ⑤The nasal resistance was statistically significant correlated with the cross-sectional area of the ventilation tubes and the obstruction sites. The correlation coefficients were -0.895 and 0.339, respectively （P<0.05）. Conclusion:①3D printing can quickly and accurately replicate anatomical structure of the nasal cavity, and can be used as a research method for quantifitative measurement of nasal resistance. ②The minimum cross-sectional area of nasal cavitiy is the main determinant of nasal resistance. ③The obstruction site is the secondary determinant of nasal resistance. When the degree of nasal obstruction is the same , the nasal resistance in the nasal valve area is sightly higher than that in the common meatus.