Relationship Between Degree of Obstruction and Airflow Limitation in Subglottic Stenosis
Relationship Between Degree of Obstruction and Airflow Limitation in Subglottic Stenosis
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DOI：
10.1002/lary.27006
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发表时间：
2018-07-01
期刊：
影响因子：
2.6
通讯作者：
Garcia, Guilherme J. M.
中科院分区：
文献类型：
--
作者：
Lin, Emily L.;Bock, Jonathan M.;Garcia, Guilherme J. M.
目的：声门下狭窄（SGS）是儿科患者最常见的气道疾病之一。目前，治疗决策主要依赖于 Cotton-Myer 量表，该量表根据空域横截面积 (CSA) 的减少百分比对 SGS 严重程度进行分类。然而，上气道阻力与声门下 CSA 之间的精确关系尚不清楚。我们假设气道阻力可以用伯努利阻塞理论来描述，该理论预测在严重收缩的情况下，气道阻力与空域 CSA 成反比（R 与 A(-1) 成正比）。方法：使用 6 名健康受试者和 5 名 SGS 患者的计算机断层扫描 (CT) 扫描来创建从鼻孔到隆突的呼吸道三维模型。将不同长度和不同直径的圆柱段以数字方式插入健康受试者的声门下，以创建模拟 SGS 模型。进行了计算流体动力学模拟，并在模拟 SGS 模型和实际 SGS 模型中计算了气道阻力。结果：收缩直径对气道阻力的影响大于收缩长度。与伯努利阻塞理论一致，模拟 SGS 模型中的气道阻力可以用幂律 R=aA(b) 很好地表示，其中 a 是常数，指数 b 的范围为 -0.85 至 -1.07。研究发现，在恒定压降下气流减少的百分比 (Q(阻塞)/Q(健康)) 与严重收缩限制下 CSA 的减少百分比 (A(阻塞)/A(健康)) 成正比，即 Q(阻塞)/Q(健康)=kA(阻塞)/A(健康)，其中 k=2: 25 +/- 0: 15。模拟 SGS 模型中的阻力与基于实际 SGS 患者 CT 扫描的模型中的阻力相似，这表明我们模拟的 SGS 模型代表了实际 SGS 患者的气道阻力。 结论：我们的计算机模拟表明，SGS 患者的气流受限程度可以仅根据解剖测量来估计。建议未来的研究在更大的群体中测试这些预测。
Objectives: Subglottic stenosis (SGS) is one of the most common airway disorders in pediatric patients. Currently, treatment decisions rely primarily on the Cotton-Myer scale, which classifies SGS severity based on percentage reduction in airspace cross-sectional area (CSA). However, the precise relationship between upper airway resistance and subglottic CSA is unknown. We hypothesize that airway resistance can be described by the Bernoulli Obstruction Theory, which predicts that airway resistance is inversely proportional to airspace CSA (R proportional to A(-1)) in cases of severe constriction.Methods: Computed tomography (CT) scans of six healthy subjects and five SGS patients were used to create three-dimensional models of the respiratory tract from nostrils to carina. Cylindrical segments of varying lengths and varying diameters were digitally inserted in the subglottis of the healthy subjects to create simulated SGS models. Computational fluid dynamics simulations were run, and airway resistance was computed in the simulated SGS models and actual SGS models.Results: Constriction diameter had a greater impact in airway resistance than constriction length. In agreement with the Bernoulli Obstruction Theory, airway resistance in the simulated SGS models was well represented by the power law R=aA(b), where a is a constant and the exponent b ranged from -0.85 to -1.07. The percentage reduction in airflow (Q(OBSTRUCTION)/Q(HEALTHY)) at a constant pressure drop was found to be directly proportional to the percentage reduction in CSA (A(OBSTRUCTION)/A(HEALTHY)) in the limit of severe constrictions, namely Q(OBSTRUCTION)/Q(HEALTHY)=kA(OBSTRUCTION)/A(HEALTHY), where k=2: 25 +/- 0: 15. Airway resistances in the simulated SGS models were similar to resistances in models based on CT scans of actual SGS patients, suggesting that our simulated SGS models were representative of airway resistance in actual SGS patients.Conclusion: Our computer simulations suggest that the degree of airflow limitation in SGS patients may be estimated based on anatomic measurements alone. Future studies are recommended to test these predictions in larger cohorts.