Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
J Breath Res. 2019 Jul 18;13(4):044001. doi: 10.1088/1752-7163/ab2c99.
Fractional exhaled nitric oxide (FNO) has been proposed as a non-invasive marker of inflammation in the lungs. Measuring FNO at several flow rates enables the calculation of flow independent NO-parameters that describe the NO-exchange dynamics of the lungs more precisely. The purpose of this study was to compare the NO-parameters between asthmatics and healthy subjects in a systematic review and meta-analysis.
A systematic search was performed in Ovid Medline, Web of Science, Scopus and Cochrane Library databases. All studies with asthmatic and healthy control groups with at least one NO-parameter calculated were included.
From 1137 identified studies, 33 were included in the meta-analysis. All NO-parameters (alveolar NO concentration (CNO), bronchial flux of NO (JNO), bronchial mucosal NO concentration (CNO) and bronchial wall NO diffusion capacity (DNO)) were found increased in glucocorticoid-treated and glucocorticoid-naïve asthma. JNO and CNO were most notably increased in both study groups. Elevation of DNO and CNO seemed less prominent in both asthma groups.
We found that all the NO-parameters are elevated in asthma as compared to healthy subjects. However, results were highly heterogenous and the evidence on CNO and DNO is still quite feeble due to only few studies reporting them. To gain more knowledge on the NO-parameters in asthma, nonlinear methods and standardized study protocols should be used in future studies.
分比呼出一氧化氮（FNO）已被提议作为肺部炎症的一种非侵入性标志物。在多个流速下测量 FNO 可以计算出独立于流速的 NO 参数，这些参数可以更精确地描述肺部的 NO 交换动力学。本研究的目的是通过系统评价和荟萃分析比较哮喘患者和健康受试者之间的 NO 参数。
在 Ovid Medline、Web of Science、Scopus 和 Cochrane Library 数据库中进行了系统检索。纳入了所有具有哮喘和健康对照组且至少计算了一个 NO 参数的研究。
从 1137 项确定的研究中，有 33 项被纳入荟萃分析。所有 NO 参数（肺泡 NO 浓度（CNO）、NO 支气管通量（JNO）、支气管黏膜 NO 浓度（CNO）和支气管壁 NO 扩散能力（DNO））均在接受和未接受糖皮质激素治疗的哮喘中升高。JNO 和 CNO 在两个研究组中均显著增加。在两个哮喘组中，DNO 和 CNO 的升高似乎不太明显。
与健康受试者相比，我们发现所有的 NO 参数在哮喘中均升高。然而，结果高度异质，由于只有少数研究报告了 CNO 和 DNO，因此关于它们的证据仍然相当薄弱。为了更深入地了解哮喘中的 NO 参数，未来的研究应该使用非线性方法和标准化研究方案。
