title: Absence of hyperresponsiveness to methacholine in a worker with methylene diphenyl diisocyanate (MDI)-induced asthma.
abstract: A 29-year-old man had a persuasive history of respiratory illness following exposures to methylene diphenyl diisocyanate (MDI). He was evaluated by measuring bronchial reactivity to methacholine, both before and after controlled laboratory exposures to MDI. Despite evidence of progressive declines in FEV1 with increasing (but subirritant) doses of MDI on three consecutive days, there was no bronchial hyperresponsiveness to methacholine, before or after MDI challenge. We conclude that the absence of nonspecific bronchial hyperresponsiveness does not exclude the possibility of isocyanate asthma. In the face of a compelling history, a negative result of methacholine challenge should not deter observation or laboratory testing for specific respiratory allergy to these chemicals.
mesh_terms: D000328:Adult; D001249:Asthma / Q000139:chemically induced* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D003485:Cyanates / Q000009:adverse effects*; D005188:False Negative Reactions; D005541:Forced Expiratory Volume; D006801:Humans; D017953:Isocyanates; D008297:Male; D016210:Methacholine Chloride; D008688:Methacholine Compounds; D009784:Occupational Diseases / Q000139:chemically induced* / Q000503:physiopathology; D013997:Time Factors; D014797:Vital Capacity / Q000187:drug effects; D001559:Benzhydryl Compounds
chemical_list: D003485:Cyanates; D017953:Isocyanates; D016210:Methacholine Chloride; D008688:Methacholine Compounds; C005969:4,4'-diphenylmethane diisocyanate; D001559:Benzhydryl Compounds