Hôpital du Sacré-Coeur de Montréal, Université de Montréal, Montreal, QC, Canada.
Chest. 2010 Mar;137(3):617-22. doi: 10.1378/chest.09-2081. Epub 2009 Dec 1.
The measure of sputum eosinophil counts is a useful tool in the investigation of occupational asthma (OA), but processing sputum is time consuming. Measuring the fractional concentration of exhaled nitric oxide (FENO) may be an alternative in clinical practice. The aim of this study was to assess the respective changes of sputum eosinophil counts and FENO following exposure to occupational agents in the routine practice of two tertiary centers in North America and Europe.
Workers undergoing specific inhalation challenges (SICs) for possible OA in tertiary clinics in both Canada and Belgium were enrolled. Sputum cell counts and FENO were collected at the end of the control day and at 7 and 24 h after exposure to the offending agent.
Forty-one subjects had a negative SIC; 26 subjects had OA proven by a positive SIC. In subjects with positive SIC, there was a significant increase in sputum eosinophils at 7 h (9.0 [9.9]%) and 24 h (11.9 [14.9]%) after exposure compared with the baseline (2.8 [4.2]%), whereas there was a significant increase in FENO only 24 h after exposure (26.0 [30.5] ppb) compared with the baseline (16.6 [18.5] ppb). A 2.2% change in sputum eosinophil counts achieved a much higher sensitivity and positive predictive value than a 10-ppb change in FENO with similar specificity and negative predictive value for predicting a 20% decrease in FEV(1) during SICs.
Sputum eosinophil counts constitute a more reliable tool than FENO to discriminate positive and negative SICs.
痰嗜酸性粒细胞计数是职业性哮喘（OA）研究中的一种有用工具，但处理痰液很耗时。测量呼出气一氧化氮（FENO）的分数浓度可能是临床实践中的一种替代方法。本研究旨在评估北美和欧洲两个三级中心的常规实践中，暴露于职业性抗原后痰嗜酸性粒细胞计数和 FENO 的各自变化。
在加拿大和比利时的三级诊所，对疑似 OA 进行特定吸入性挑战（SIC）的工人被纳入研究。在暴露于致病变应原结束时以及暴露后 7 小时和 24 小时采集痰液细胞计数和 FENO。
41 名受试者 SIC 为阴性；26 名受试者 SIC 阳性，证实为 OA。在 SIC 阳性的受试者中，与基线相比，暴露后 7 小时（9.0 [9.9]%）和 24 小时（11.9 [14.9]%）痰液嗜酸性粒细胞显著增加，而仅在暴露后 24 小时 FENO 显著增加（26.0 [30.5] ppb）与基线相比（16.6 [18.5] ppb）。痰嗜酸性粒细胞计数变化 2.2%的敏感性和阳性预测值明显高于 FENO 变化 10 ppb，且对预测 SIC 期间 FEV1 下降 20%的特异性和阴性预测值相似。
痰嗜酸性粒细胞计数比 FENO 更能可靠地区分 SIC 阳性和阴性。
