Airway hyperresponsiveness to methacholine in chemical warfare victims

BACKGROUND: The lung is one of the most exposable organs to chemical warfare agents such as sulfur mustard gas. Pulmonary complications as a result of this gas range from severe bronchial stenosis to mild or no symptoms. Airway hyperresponsiveness (AHR) which is usually assessed as response to inhaled methacholine is the most characteristic feature of asthma. AHR is reported in chronic obstructive pulmonary disease patients and smokers, and may also show in chemical warfare victims. However, there are little reports regarding AHR in chemical warfare victims. OBJECTIVE: Therefore, in this study, airway responsiveness to methacholine in victims of chemical warfare was examined. METHODS: The threshold concentrations of inhaled methacholine required for a 20% change in forced expiratory flow in 1 s (FEV1; PC20) or a 35% change in specific airway conductance (PC35) were measured in 15 chemical war victims and 15 normal control subjects. RESULTS: In 10 out of 15 chemical warfare victims (two thirds), PC20 and PC35 methacholine could be measured and subjects were called responders. AHR to methacholine in responder chemical war victims (PC20 = 0.41 and PC35 = 0.82 g/l) was significantly lower than in normal subjects (PC20 = 5.69 and PC35 = 4.60 g/l, p < 0.001 for both cases). There was a significant correlation between FEV1 and PC20 methacholine (r = 0.688, p < 0.001). The correlations between PC20 and PC35 were statistically significant as well (r = 0.856, p < 0.001). CONCLUSION: Results showed increased airway responsiveness of most chemical warfare victims to methacholine which correlated with the FEV1 value and which may be related to chronic airway inflammation or irreversible airway changes.