Reactive airways dysfunction syndrome after exposure to dinitrogen tetroxide

Background. Reactive airways dysfunction syndrome (RADS) is characterized b y persistent bronchial hyperreactivity and asthmatic symptoms in a previous ly healthy individual after a single intense exposure to an irritant fume, vapor, or gas. On October 23, 1995, a cloud of dinitrogen tetroxide (N2O4) escaped from a railroad tanker car in Bogalusa, Louisiana, exposing an esti mated 4,000 citizens to the gas. Methods. A sample of 234 patients with respiratory complaints after the spi ll received a complete history and physical examination, a symptom question naire, and pulmonary function tests. Patients whose previously undocumented asthma-like symptoms persisted for 3 months after exposure to N2O4 had met hacholine challenge testing. Results. Of the 234 patients evaluated, six met the criteria for a diagnosi s of RADS. The distance of these six patients from the source of the leak, their durations of exposure, and initial symptoms were not different from t hose of the sample patients who did not have RADS. Conclusions. After evaluation of 234 symptomatic patients who were exposed to N2O4, we diagnosed six cases of RADS. There were no demographic characte ristics or initial symptoms that identified patients who were at risk of ha ving this syndrome. We believe we are the first to report cases of RADS due to N2O4 exposure.