Dellabianca A, Omodeo P, Colli M C, Bianchi P, Scibilia J, Moscato G
School of Allergology and Clinical Immunology, University of Pavia, Italy.
Ann Allergy Asthma Immunol. 1996 Nov;77(5):378-84. doi: 10.1016/S1081-1206(10)63336-4.
In a previous work we have demonstrated that the use of an indirect stimulus such as ultrasonically nebulized distilled water (UNDW, "fog") challenge, in addition to methacholine, in the assessment of occupational asthma due to TDI improves our ability in detecting sensitized subjects.
In the present study we aimed to determine the validity of "fog" in the assessment of occupational asthma induced by various low molecular weight substances.
Fourty subjects exposed to low molecular weight substances with work-related respiratory symptoms underwent methacholine, UNDW and specific bronchial challenge tests. Diagnosis of occupational asthma was made in 20 of 40 patients who developed bronchoconstrictive responses to the specific challenges (reactors). Sensitivity and specificity of UNDW alone, of methacholine alone, and of the combination of the two tests were determined at two different cutpoints of PD20FEV1 of methacholine, with the results of the specific challenge as the "gold standard".
Frequency and severity of bronchial hyperresponsiveness both to UNDW and to methacholine were significantly higher in reactors than in nonreactors. Ultrasonically nebulized distilled water had higher specificity (80% versus 60%) but lower sensitivity (65% versus 75% to 90%) than methacholine. As compared with methacholine alone, the combination in series of the two challenges (both challenges positive) substantially improved specificity (85% versus 60%).
In conclusion, in the assessment of low molecular weight chemical-induced asthma diagnosed with the specific challenge as the "gold standard," UNDW challenge proves more specific than methacholine for occupational asthma, but it is considerably less sensitive. The combination of the two challenges results in very high sensitivity and high specificity for occupational asthma, therefore, although further investigations are required for the definitive diagnosis, it should be regarded as a useful means to confirm objectively a suggestive history.
在之前的一项研究中，我们已经证明，在评估因甲苯二异氰酸酯（TDI）导致的职业性哮喘时，除了使用乙酰甲胆碱外，采用间接刺激物如超声雾化蒸馏水（UNDW，“雾”）激发试验，可提高我们检测致敏个体的能力。
在本研究中，我们旨在确定“雾”激发试验在评估由各种低分子量物质诱发的职业性哮喘中的有效性。
40名暴露于低分子量物质且有与工作相关呼吸道症状的受试者接受了乙酰甲胆碱、UNDW和特异性支气管激发试验。40名患者中有20名在特异性激发试验（反应者）中出现支气管收缩反应，被诊断为职业性哮喘。以特异性激发试验结果为“金标准”，在乙酰甲胆碱PD20FEV1的两个不同切点处，分别测定单独使用UNDW、单独使用乙酰甲胆碱以及两种试验联合使用时的敏感性和特异性。
反应者对UNDW和乙酰甲胆碱的支气管高反应性的频率和严重程度均显著高于非反应者。超声雾化蒸馏水的特异性（80%对60%）高于乙酰甲胆碱，但敏感性（65%对75%至90%）低于乙酰甲胆碱。与单独使用乙酰甲胆碱相比，两种激发试验串联组合（两种激发试验均为阳性）可显著提高特异性（85%对60%）。
总之，在以特异性激发试验为“金标准”诊断的低分子量化学物质诱发的哮喘评估中，UNDW激发试验对职业性哮喘的特异性高于乙酰甲胆碱，但敏感性明显较低。两种激发试验联合使用对职业性哮喘具有很高的敏感性和特异性，因此，尽管明确诊断还需要进一步研究，但它应被视为客观证实可疑病史的有用手段。
