Need for Monitoring Nonspecific Bronchial Hyperresponsiveness Before and After Isocyanate Inhalation Challenge
2003; Elsevier BV; Volume: 123; Issue: 4 Linguagem: Inglês
10.1378/chest.123.4.1276
ISSN1931-3543
AutoresJ. Sastre, Mar Fernández‐Nieto, Ana Novalbos, Manuel de las Heras, Javier Cuesta, Santiago Quirce,
Tópico(s)Indoor Air Quality and Microbial Exposure
ResumoSpecific and nonspecific bronchial responsiveness may decline or disappear after cessation of exposure in the workplace in patients with occupational asthma, leading to false-negative specific inhalation challenge (SIC) results.Twenty-two patients with suspected diisocyanate-induced asthma were studied. SIC with diisocyanates (toluene diisocyanate [TDI] or hexamethylene diisocyanate [HDI]) was carried out in a 7-m(3) dynamic chamber up to a maximum concentration of 19 parts per billion for 120 min. Methacholine inhalation challenges were performed before and 24 h after SIC with TDI or HDI. Patients who did not show an asthmatic reaction after SIC but had a greater than twofold reduction in provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)) after the first isocyanate challenge underwent a second isocyanate SIC 2 days later.The first SIC with isocyanates elicited an asthmatic reaction in 13 patients (59%). In five patients who did not show an asthmatic reaction after the first SIC, PC(20) exhibited more than a twofold reduction. In three of the five patients, a second SIC with isocyanates elicited an immediate positive asthmatic reaction. Therefore, 3 of 16 patients (19%) were ultimately shown to have bronchial responsiveness to isocyanate; occupational asthma was demonstrated due to post-SIC monitoring of bronchial hyperresponsiveness to methacholine.PC(20) should be systematically assessed before and after SIC with isocyanates in the absence of significant changes in FEV(1) during SIC to avoid false-negative results.
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