Study And Clinical Application Of Numerical Model Related To NO Concentration Distribution In Nasal-paranasal Sinusitis

Nitric oxide(NO)plays an important role in maintaining the physiological functions of nasal cavity and sinuses.It has the functions of anti-bacteria,anti-fungi,anti-virus,promoting the secretion of nasal mucosal glands,maintaining mucociliary transport and regulating the tension of nasal mucosal vessels.The changes and abnormal distribution of NO in nasal cavity and sinus are closely related to the occurrence and development of nasal cavity and sinus diseases.At present,NO has been widely used to monitor the immunity and inflammation of nasal-paranasal sinuses at home and abroad,but the distribution and flow of NO concentration in human nasal cavity and paranasal sinuses are not very clear.The relationship between the distribution and level of NO concentration in nasal-paranasal sinuses and the inflammation of nasal-paranasal sinuses is still unclear.Nowadays,the distribution of NO concentration in nasal cavity and sinuses under normal and inflammation conditions is indirectly understood by measuring the concentration of NO in nasal exhaled breath,and the relationship between the distribution of NO concentration and nasal-sinusitis is inferred through this detection value.However,there are great differences in the current domestic and foreign research results,which fails to form a unified and accepted reference value.Moreover,the structure of nasal cavity and paranasal sinuses is complex,and the concentration of NO in nasal exhaled air can not really replace the distribution of NO concentration in the specific parts of nasal cavity and paranasal sinuses.Therfore,In this study,a numerical model of NO concentration distribution in nasal cavity and paranasal sinuses was established from the biomechanical point of view.The distribution and flow of NO concentration in nasal cavity and paranasal sinuses were simulated and analyzed under normal conditions and before and after sinusitis surgery by using computational fluid dynamics.This study mainly consists of the following parts:Section 1:Objective: To study the distribution of NO concentration in nasal cavity and sinuses and to understand the airflow in nasal cavity closely related to it.Methods: High resolution CT images of nasal cavity and paranasal sinuses of a volunteer were obtained,and a numerical model was established.The characteristics of airflow field were analyzed by numerical simulation.Results: The total and middle nasal airflow was the largest,the inferior nasal airflow was the second,and the olfactory fissure area was the smallest.Conclusions: Total nasal airflow acts as ventilation,and middle nasal airflow may play a role in bringing NO discharged from maxillary sinus to nasal cavity and upper and lower respiratory tract.The airflow in olfactory fissure area serves for olfactory sense.Section 2: Objective: To study the physiological role of NO concentration distribution,flow and NO distribution in the function of nasal cavity and sinus in healthy people,and to verify the credibility of the numerical model simulation results;through numerical simulation,to find a non-invasive and direct method for calculating NO concentration in nasal cavity and maxillary sinus.Methods: On the basis of the first section of the numerical model,the air flow field characteristics of NO in nasal cavity,nasal sinus and nasopharynx were analyzed by adding the mixture of NO and air in maxillary sinus,and the reliability of the model results was verified by comparing the ratio of NO concentration in nasal exhalation with that in maxillary sinus with that in the literature.The concentration of NO in maxillary sinus of different sizes was set,and the corresponding concentration of NO in nasal exhalation was calculated by numerical simulation.The positive linear relationship between the two was tested,and the ratio K was calculated.Results: The amount of NO entering the opposite side during expiratory phase was very small.The higher the concentration of NO near the ostium of nasal sinus,the higher the concentration gradient from the ostium of maxillary sinus to the far side,and the closer to the nasal cavity and the lateral wall of nasopharynx.NO flows in the nasal cavity with the respiratory airflow.When inhaling and exhaling,the airflow is mostly confined to the middle nasal passage.It enters the nasopharynx backward and goes out the front nostril forward and downward.NO can almost fill the nasal cavity at the beginning of exhalation.The concentration of NO in nasopharynx during inhalation period is relatively high;the ratio of NO concentration in nasal exhalation and maxillary sinus calculated by numerical simulation in this study is within the range of the latter;the concentration of NO in anterior nasal exhalation is directly proportional to the concentration of NO in maxillary sinus,and the ratio k is calculated.Conclusions: NO has little effect on the concentration of NO in contralateral nasal cavity.The concentration distribution of NO in nasal cavity and nasopharynx of healthy people has gradient,and varies with breathing time.Different concentrations play their physiological roles in different parts.The numerical simulation of nasal cavity and sinus can make qualitative and quantitative analysis of the concentration distribution of NO in nasal cavity and sinus individually.The ratio of NO concentration in nasal exhalation and maxillary sinus calculated by numerical simulation in this study is compared with the ratio in the literature.It is believed that the numerical simulation results in this study are credible.It is a non-invasive,direct and convenient method to calculate the concentration of NO in nasal cavity and paranasal sinuses by numerical simulation.Because the ratio of the two is consistent with the calculated ratio k in clinical practice,we can study the distribution of NO in nasal cavity and paranasal sinuses by studying the ratio k.Section 3: Objective: To study the influence of different volume flow rates on the distribution of NO concentration in nasal cavity and the concentration of NO in nasal exhalation during expiratory period,and to study the correlation between the change of NO concentration distribution in nasal cavity caused by different flow rates and the occurrence and treatment of nasal-sinusitis.Methods: On the basis of the second part of the numerical model,the volume velocity condition of nasopharyngeal entrance was changed to calculate the distribution of NO concentration in nasal cavity and nasal exhaled air.Results: If the output of NO is fixed in maxillary sinus,the larger the volume velocity or flow of exhaled gas,the smaller the concentration gradient of NO in nasal cavity,the smaller the distribution range,the lower the concentration of NO in nasal exhaled gas,and the concentration gradient of NO in anterior nostril.Conclusions: The distribution of NO concentration in nasal cavity and the concentration of NO in nasal exhaled air are closely related to the volume flow rate and flow rate of nasal gas,and are negatively correlated.The measurement of nasal exhaled air should unify the measurement of exhaled air volume flow rate or flow rate and the direction and depth of the measurement head,and the shorter the measurement time,the better,which is conducive to the formation and unification of the standard measurement value of nasal exhaled air NO concentration.Section 4: Objective: To study the distribution of NO concentration in nasal cavity and paranasal sinuses after the size change of maxillary sinus orifice,and to understand the influence of the size change of sinus orifice on the occurrence and development of sinusitis and the causes of persistence and recurrence after open sinus orifice surgery.Methods: On the basis of the second part of the numerical model,five models with different sizes of the maxillary ostium were established by changing the size of one side of the maxillary ostium,and two models with different sizes of the maxillary ostium were established to calculate the NO concentration distribution in the nasal cavity,anterior nasal ostium and the NO concentration distribution in the sinus.Results: The smaller the sinus orifice,the smaller the concentration gradient of NO around the sinus orifice,the lower the concentration of NO in the nasal cavity,the smaller the distribution range and the smaller the concentration of NO in the nasal exhaled air.The larger the sinus orifice,the lower the sinus orifice concentration around the sinus orifice,and the more obvious the concentration gradient.Conclusions: The shrinkage of sinus orifice caused by mucosal swelling and polyp formation be an important cause of sinusitis.The concentration of NO in nasal exhaled breath can be used as an index to determine whether the maxillary sinus ostium is unobstructed or not.Excessive opening of sinus orifice may be one of the important reasons for persistent or repeated inflammation in maxillary sinus.Section 5: Objective: To study the effect of maxillary sinus empyema,trauma and surgery on the distribution of NO concentration in nasal cavity.Methods: On the basis of the second part of the numerical model,the volume of maxillary sinus was changed and four different volume models were established.The distribution of NO concentration in nasal cavity was calculated under the same conditions.Results: The volume of maxillary sinus changed,but the distribution of NO concentration in nasal cavity had no difference.When the volume of maxillary sinus is reduced,the relative volume of NO-producing mucosa surface decreases slowly,which may have little effect on the concentration of NO in nasal cavity and nasal exhaled gas.Conclusion: The reduction of maxillary sinus volume caused by surgery or trauma may not affect the distribution of NO concentration in nasal cavity and its physiological function,but the reduction of maxillary sinus volume caused by inflammation needs further study.Section 6: Objective: To understand whether the operation of middle turbinate and the lesions of middle nasal meatus will affect the distribution of NO concentration in nasal cavity and the concentration of NO in nasal exhaled air through the influence of the change of transverse diameter of middle nasal meatus on the concentration of NO in nasal cavity and nasal exhaled air during sinusitis.Methods: On the basis of the second part of the numerical model,the volume of the middle nasal meatus was enlarged transversely.The distribution of NO concentration in nasal cavity and the concentration of NO in nasal exhaled air were calculated and compared with the results of the second part of the healthy people.Results: The numerical simulation showed that the transverse diameter of the middle nasal meatus widened and the concentration of NO in other parts except the middle nasal meatus increased.Conclusions:The enlargement of middle nasal meatus leads to the increase of NO concentration in nasal cavity and nasopharynx,which affect the physiological function of upper and lower respiratory tract.It is suggested that when measuring the concentration of NO in nasal exhaled air before and after sinusitis,combined with whether there is a change in the transverse diameter of the middle nasal tract,which is conducive to the unification and reduction of the concentration of NO in nasal exhaled air,and can more accurately reflect the postoperative recovery of sinusitis and the opening of sinus ostium.Section 7: Studies on the contents of NO and nitric oxide synthase in the mucosa of maxillary sinus in sinusitisObjective: To investigate whether the concentration of NO in nasal sinuses increases under the condition of sinusitis indirectly by detecting the amount of NO and nitric oxide synthase in nasal mucosa,to analyze the causes of the decrease of NO concentration in nasal exhaled air during sinusitis,and to analyze the mechanism of NO involvement in the pathogenesis of sinusitis.Methods: The amount of NO and NOS in sinusitis and sinus mucosa specimens of control group were detected and compared.Results: NO and NO synthase were the highest in fungal sinusitis group,followed by chronic sinusitis group and the lowest in control group.Conclusion: The change of NO concentration is one of the important factors for the pathogenesis of sinusitis.The concentration of NO in sinuses may also increase during sinusitis.Combined with the numerical study of the influence of sinus orifice size on the concentration of NO in nasal cavity,the decrease of NO concentration in nasal exhaled breath of sinusitis is probably due to the decrease of sinus orifice.