论文部分内容阅读
目的研究典型男性阻塞性睡眠呼吸暂停低通气综合症(OSAHS)患者在平静呼吸时上气道气流运动特性,以及气流对软腭和悬雍垂作用的动力特点。方法基于患者CT影像数据建立可靠的上气道流场几何模型,以临床睡眠监测数据作为数值模拟边界条件的依据,采用低雷诺数的湍流模型计算获得一个完整呼吸周期内上气道气流运动规律。结果 OSAHS患者在呼吸过程中,上气道气流流动形式有显著差异。在吸气阶段,上气道腔内流速可达9.808 m/s,最大负压可达-78.856 Pa,鼻腔顶部出现局部回流,软腭受到的最大气流压力为-10.884 Pa,悬雍垂受到的最大气流压力为-51.946 Pa,气流对软腭和悬雍垂造成的最大剪切应力分别为78和311 mPa。在呼气阶段,上气道腔内最大流速为10.330 m/s,最大负压为-51.921 Pa,口咽部和鼻腔顶部均出现局部回流,且口咽部顺时针回流现象显著,软腭受到的最大气流压力为2.603 Pa,悬雍垂受到的最大气流压力为-18.222 Pa,软腭和悬雍垂受到的最大剪切应力分别为51和508 mPa。结论口咽部是易塌陷的部位,一个呼吸循环过程的数值模拟可以捕捉到上气道流场显著的回流特征,上气道回流直接影响软腭和悬雍垂所受的力,同时也关系到患者呼吸的流畅程度。
Objective To investigate the characteristics of upper airway airflow in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) during calm breathing and the dynamic characteristics of airflow on soft palate and uvula. Methods Based on the CT images of the patients, a reliable geometric model of the upper airway flow field was established. Based on the data of clinical sleep monitoring data and the numerical simulation of boundary conditions, a turbulence model with low Reynolds number was used to calculate the airflow pattern of the upper airway during a complete respiratory cycle . Results There was a significant difference in the airflow patterns of the upper airway during OSAHS. In the inspiratory phase, the maximum air pressure in the upper airway reached to 9.808 m / s, the maximum negative pressure reached -78.856 Pa, local reflux occurred at the top of the nasal cavity, the maximal airflow pressure on the soft palate was -10.884 Pa, and the uvula received the maximum The airflow pressure was -51.946 Pa. The maximum shearing stress caused by airflow on the soft palate and uvula was 78 and 311 mPa, respectively. During the expiratory phase, the maximal flow velocity in the upper airway was 10.330 m / s and the maximum negative pressure was -51.921 Pa. Local reflux was observed in the oropharyngeal and nasal cavities, and the oropharyngeal clockwise reflux phenomenon was significant. The maximum airflow pressure was 2.603 Pa, the maximum airflow pressure on the uvula was -18.222 Pa, and the maximum shear stress on the soft palate and uvula was 51 and 508 mPa, respectively. Conclusions The oropharynx is prone to collapsing. A numerical simulation of the respiratory cycle can capture the significant reflux characteristics of the upper airway flow field. The upper airway reflux directly affects the force exerted by the soft palate and uvula, and is also related to The patient’s degree of flu to breathe.