The great majority of subjects exposed to irritant spillsdo not develop RADS. Most symptomatic individuals recover within a few days. Early symptoms are often related to upper airway irritation, and are more common in smokers and asthmatics. Persistent respiratory symptoms and AHR occur in 10% or less of exposed individuals. The definition of RADS does not require spirometric evidence of airflow limitation, nor does it necessitate the demonstration of spontaneous airflow variability or a significant bronchodilator response. On the contrary, pulmonary function tests are often normal, and when airflow obstruction exists it may fail to improve significantly with bronchodilation. asthma inhalers
The degree of AHR reported for most cases of RADS is often mild. Pathological findings are not constant with bronchial biopsies showing varying degrees of inflammation and fibrotic changes.
Figure 4) One-week follow-up lung resistance (Rl) (a), lung elasticity (El) (b) and the concentration of methylcholine required to double Rl (EC200RL) (c). Control animals (n=3, open symbols; mean ± SE) and study group data (n=11), and individual (lines) and group means ± SE (solid squares) are shown. The apparent trend of increase inRLvalues was not significant. Study group means did not change significantly and were similar to those of the control animals