Department of Civil, Chemical and Environmental Engineering, University of Genova, Via Montallegro, 1, 16145, Genoa, Italy.
Department of Aerospace Sciences and Technologies, Politecnico di Milano, Campus Bovisa, 20156, Milano, Italy.
Biomech Model Mechanobiol. 2024 Feb;23(1):305-314. doi: 10.1007/s10237-023-01776-5. Epub 2023 Oct 30.
Nasal breathing difficulties (NBD) are widespread and difficult to diagnose; the failure rate of their surgical corrections is high. Computational fluid dynamics (CFD) enables diagnosis of NBD and surgery planning, by comparing a pre-operative (pre-op) situation with the outcome of virtual surgery (post-op). An equivalent comparison is involved when considering distinct anatomies in the search for the functionally normal nose. Currently, this comparison is carried out in more than one way, under the implicit assumption that results are unchanged, which reflects our limited understanding of the driver of the respiratory function. The study describes how to set up a meaningful comparison. A pre-op anatomy, derived via segmentation from a CT scan, is compared with a post-op anatomy obtained via virtual surgery. State-of-the-art numerical simulations for a steady inspiration carry out the comparison under three types of global constraints, derived from the field of turbulent flow control: a constant pressure drop (CPG) between external ambient and throat, a constant flow rate (CFR) through the airways and a constant power input (CPI) from the lungs can be enforced. A significant difference in the quantities of interest is observed depending on the type of comparison. Global quantities (flow rate, pressure drop and nasal resistance) as well as local ones are affected. The type of flow forcing affects the outcome of the comparison between pre-op and post-op anatomies. Among the three available options, we argue that CPG is the least adequate. Arguments favouring either CFR or CPI are presented.
鼻腔呼吸障碍（NBD）很常见，且难以诊断；其手术矫正的失败率很高。计算流体动力学（CFD）通过比较术前（术前）情况和虚拟手术（术后）的结果，来诊断 NBD 和规划手术。在寻找功能正常的鼻子时，考虑不同的解剖结构也需要进行类似的比较。目前，这种比较是通过多种方式进行的，隐含的假设是结果保持不变，这反映了我们对呼吸功能驱动因素的理解有限。该研究描述了如何进行有意义的比较。通过从 CT 扫描中进行分割得到术前解剖结构，并与通过虚拟手术获得的术后解剖结构进行比较。在三种全局约束条件下进行了稳态吸气的先进数值模拟，这些约束条件来自湍流流动控制领域：外部环境与喉咙之间的恒定压降（CPG）、气道中的恒定流量（CFR）和来自肺部的恒定功率输入（CPI）可以得到强制执行。根据比较的类型，观察到感兴趣的数量存在显著差异。全局数量（流量、压降和鼻阻力）和局部数量都会受到影响。流量强制的类型会影响术前和术后解剖结构之间的比较结果。在三种可用选项中，我们认为 CPG 最不合适。提出了支持 CFR 或 CPI 的论点。
