Induced sputum and exhaled nitric oxide as noninvasive markers of airway inflammation from work exposures.

PURPOSE OF REVIEW: Noninvasive measures of airway inflammation are increasingly used in the investigation and management of asthma. Their role in the investigation of occupational lung diseases, however, is not as clearly established. The present article reviews the use of noninvasive methods - induced sputum and exhaled nitric oxide - in the assessment of airway inflammation during the investigation of occupational asthma and eosinophilic bronchitis, and reviews studies investigating the effect of exposure to various occupational agents on airway inflammation in healthy individuals.

RECENT FINDINGS: A number of studies have confirmed the association between exposure to occupational agents and the presence of eosinophilic airway inflammation after that exposure in individuals with occupational asthma. Individuals with positive specific inhalation challenges to occupational agents seem to show a greater increase in exhaled nitric oxide than those with negative specific inhalation challenges. Exposure to various agents associated with an increase in exhaled nitric oxide mainly induced a neutrophilic inflammation.

SUMMARY: Increasing evidence supports the use of induced sputum as an additional tool in the investigation of occupational asthma. The role of exhaled nitric oxide in the investigation of occupational asthma needs to be clarified due to conflicting evidence reported in the literature.