Background

Nitric oxide (NO) is important in respiratory physiology and airway defense. Although the paranasal sinuses are the major source of nasal NO, transport dynamics between the sinuses and nasal cavities are poorly understood.

Methods

Exhaled nasal NO tracings were measured in two non-asthmatic subjects (one with allergic rhinitis, one without) using NO analyzer connected via face mask. We subsequently performed computational fluid dynamics NO emission simulations based on individual CT scans and compared to the experimental data.

Results

Simulated exhaled NO tracings match well with experimental data (r > 0.84, p < 0.01) for both subjects, with measured peaks reaching 319.6 ppb in one subject (allergic-rhinitis), and 196.9 ppb in the other. The CFD simulation accurately captured the peak differences, even though the initial sinus NO concentration for both cases was set to the same 9000 ppb based on literature value. Further, the CFD simulation suggests that ethmoid sinuses contributed the most (>67%, other sinuses combined <33%) to total nasal NO emission in both cases and that diffusion contributes more than convective transport. By turning off diffusion (setting NO diffusivity to ~0), the NO emission peaks for both cases were reduced by >70%.

Conclusion

Historically, nasal NO emissions were thought to be contributed mostly by the maxillary sinuses (the largest sinuses) and active air movement (convection). Here, we showed that the ethmoid sinuses and diffusive transport dominate the process. These findings may have a substantial impact on our view of nasal NO emission mechanisms and sinus physiopathology in general.

中文翻译：

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来自鼻旁窦的鼻一氧化氮通量的计算模型：针对人体实验的验证

背景

一氧化氮 (NO) 在呼吸生理学和气道防御中很重要。虽然鼻窦是鼻腔 NO 的主要来源，但对鼻窦和鼻腔之间的运输动力学知之甚少。

方法

使用通过面罩连接的 NO 分析仪在两名非哮喘受试者（一名患有过敏性鼻炎，一名没有）中测量呼出的鼻腔 NO 追踪。我们随后基于单个 CT 扫描进行了计算流体动力学 NO 排放模拟，并与实验数据进行了比较。

结果

模拟呼出的 NO 追踪与两名受试者的实验数据 (r > 0.84, p < 0.01) 非常匹配，其中一名受试者（过敏性鼻炎）的测量峰值达到 319.6 ppb，另一名受试者为 196.9 ppb。即使根据文献值将两种情况的初始窦 NO 浓度设置为相同的 9000 ppb，CFD 模拟也准确地捕获了峰值差异。此外，CFD 模拟表明筛窦在两种情况下对总鼻腔 NO 排放的贡献最大（>67%，其他鼻窦合计 <33%），并且扩散的贡献大于对流传输。通过关闭扩散（将 NO 扩散率设置为 ~0），两种情况下的 NO 排放峰都降低了 >70%。

结论

从历史上看，鼻内 NO 排放被认为主要是由上颌窦（最大的鼻窦）和主动空气运动（对流）贡献的。在这里，我们发现筛窦和弥散性运输主导了这一过程。这些发现可能对我们对鼻 NO 排放机制和鼻窦生理病理学的看法产生重大影响。