Exhaled Nitric Oxide Levels After Specific Inahalatory Challenge Test in Subjects with Diagnosed Occupational Asthma

Abstract

Objectives: Measuring exhaled nitric oxide (eNO) is a useful method for the assessment of bronchial inflammation in asthmatic subjects. The aim of the study was to evaluate the changes in eNO level in the subjects with suspected occupational asthma (OA) after a specific inhalation test (SIT) with occupational agents. Materials and Methods: Forty two patients, including 17 farmers, 15 bakers and 10 health care workers had a physical examination, skin prick tests with common and occupational allergens, total serum IgE level, specific anti-allergen IgE determinations, spirometry and SIT. Also, morphological changes in induced sputum (ISP) and nasal lavage fluid (NLF) were analysed and eNO measurements were performed. Results: SIT revealed a significant increase in the proportion of eosinophils in NLF and in ISP in the cases with diagnosed OA. Moreover, these cases showed significantly increased eNO levels only 24 h after SIT, compared to the measurements before SIT. We also found a significant correlation between eNO level at 24 h after SIT and the percentage of eosinophils in NLF before, and 4 and 24 h after SIT, as well as in ISP before and 24 h after SIT in all subjects with diagnosed OA. Conclusion: The findings may confirm the usefulness of exhaled nitric oxide measurements for diagnosing OA.

Changes in Exhaled Nitric Oxide Levels After Bronchial Allergen Challenge

“…This observation is consistent with previous studies that used common [14][15][16]26] and occupational allergens [27,28].…”

Across-shift changes of exhaled nitric oxide and spirometric indices among cotton textile workers

“…In a study on potroom workers, Lund et al have found significantly higher FeNO concentrations than in a control group, and this measure was also higher among those with asthmatic symptoms [23]. In another study, which was conducted for assessment of occupational asthma in health care workers, farmers and bakers, the authors have found a significant increase in FeNO after a specific inhalation test with relevant allergens [24]. Studies have shown an increase in respiratory complaints and decrease in spirometric parameters among cotton workers, but the effect of cotton dust inhalation on acrossshift FeNO changes and its relationship with respiratory complaints is not fully understood.…”

“…For assessment of airway inflammation, non-invasive methods such as Exhaled Breath Condensate (EBC), induced sputum, fractional exhaled nitric oxide (FeNO) can be used, but there is no consensus on the use of these methods for evaluation of occupational respiratory diseases [17]. Many studies have shown an increase in FeNO among subjects with airway hyper-responsiveness [18][19][20][21][22], but only few studies have assessed changes of this index for detection of occupational asthma [23][24][25][26]. In a study on potroom workers, Lund et al have found significantly higher FeNO concentrations than in a control group, and this measure was also higher among those with asthmatic symptoms [23].…”

Specific inhalation challenge in the diagnosis of occupational asthma: consensus statement

“…There have been conflicting data on the changes in FeNO after SIC with occupational agents [87][88][89][90][91][92][93][94][95]. A significant increase in FeNO level was observed only 24 h after positive challenges, while there was a significant increase in sputum eosinophil at 7 h [92,96].…”