Department of Respiratory Disease, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Respir Res. 2010 Apr 30;11(1):50. doi: 10.1186/1465-9921-11-50.
The non-invasive assessment of airway inflammation is potentially advantageous in asthma management. Exhaled carbon monoxide (eCO) measurement is cheap and has been proposed to reflect airway inflammation and oxidative stress but current data are conflicting. The purpose of this meta-analysis is to determine whether eCO is elevated in asthmatics, is regulated by steroid treatment and reflects disease severity and control.
A systematic search for English language articles published between 1997 and 2009 was performed using Medline, Embase and Cochrane databases. Observational studies comparing eCO in non-smoking asthmatics and healthy subjects or asthmatics before and after steroid treatment were included. Data were independently extracted by two investigators and analyzed to generate weighted mean differences using either a fixed or random effects meta-analysis depending upon the degree of heterogeneity.
18 studies were included in the meta-analysis. The eCO level was significantly higher in asthmatics as compared to healthy subjects and in intermittent asthma as compared to persistent asthma. However, eCO could not distinguish between steroid-treated asthmatics and steroid-free patients nor separate controlled and partly-controlled asthma from uncontrolled asthma in cross-sectional studies. In contrast, eCO was significantly reduced following a course of corticosteroid treatment.
eCO is elevated in asthmatics but levels only partially reflect disease severity and control. eCO might be a potentially useful non-invasive biomarker of airway inflammation and oxidative stress in nonsmoking asthmatics.
气道炎症的无创评估在哮喘管理中具有潜在优势。呼出气一氧化碳（eCO）测量价格便宜，并已被提议反映气道炎症和氧化应激，但目前的数据存在矛盾。本荟萃分析的目的是确定 eCO 在哮喘患者中是否升高，是否受类固醇治疗调节，以及是否反映疾病严重程度和控制情况。
使用 Medline、Embase 和 Cochrane 数据库对 1997 年至 2009 年期间发表的英文文献进行了系统搜索。纳入了比较非吸烟哮喘患者和健康受试者或哮喘患者在接受类固醇治疗前后 eCO 的观察性研究。数据由两名研究者独立提取，并使用固定或随机效应荟萃分析生成加权均数差异，具体取决于异质性程度。
荟萃分析纳入了 18 项研究。与健康受试者相比，哮喘患者的 eCO 水平明显升高，与持续性哮喘相比，间歇性哮喘的 eCO 水平也明显升高。然而，在横断面研究中，eCO 无法区分接受类固醇治疗的哮喘患者和无类固醇治疗的患者，也无法区分控制良好和部分控制的哮喘与未控制的哮喘。相比之下，在接受皮质类固醇治疗后，eCO 显著降低。
eCO 在哮喘患者中升高，但水平仅部分反映疾病严重程度和控制情况。eCO 可能是一种潜在有用的非侵入性生物标志物，用于衡量非吸烟哮喘患者的气道炎症和氧化应激程度。
