Nasal response in patients with diisocyanate asthma

Abstract

Background: To date, no studies have assessed nasal and bronchial response to diisocyanates during specific inhalation challenges (SIC). Objectives: This study was performed to assess nasal response during SIC with diisocyanates (nasal and oral breathing) in patients with suspected occupational asthma due to these agents. Methods: Fourteen patients with suspected clinical history of diisocyanate-induced asthma were challenged with diisocynates in a 7m3 chamber. Nasal response testing during challenges was assessed by acoustic rhinometry, peak nasal inspiratory flow (PNIF), and visual analog scale (VAS), alongside bronchial responses. Results: Eleven patients had a significant asthmatic response to diisocyanates. None reported clear work-related nasal symptoms. In patients with positive bronchial response to diisocyanates, nasal mean minimal cross-sectional area (MCA) decreased by 26.9%, nasal volume at 5 cm decreased by 33.5%, and PNIF decreased by 28.3%, all from baseline. A positive nasal response was elicited in 45%, 54%, and 45% of patients, respectively. A significant increase in VAS was observed in 4 patients. Three patients with negative bronchial response had a negative nasal response. Conclusion: SIC revealed an objective nasal response in around 50% of patients with occupational asthma due to diisocyanates, in spite of the fact that none of them reported work-related nasal symptoms. The clinical significance of this finding is a poor association between nasal symptoms at work and an objective nasal response during positive SIC with diisocyanates.