Studies dealing with occupational exposures as diverse as colophony fumes, crab processing, isocyanates, and western red cedar reveal that only about 20% to 40% of patients will experience a gradual disappearance of their airway hyperresponsiveness after removal from the exposure for periods of one to six years. Improvement in responsiveness correlates with the duration and magnitude of the exposure. Reexposure leads to a recurrence of symptoms. These results suggest that the increased airway responsiveness is, at least in part, acquired as a result of exposure. The relatively poor remission rate, coupled with the knowledge that asthma accelerates decline in lung function, clearly has implications for what constitutes impairment from asthma. buy flovent inhaler
A framework for asthma impairment must consider four issues: (1) an adequate definition of disease, (2) clear indices of disease severity, (3) ability to attribute impairment to the exposure, and (4) a predictable prognosis. Only when we have reasonable clinical consensus on these four points can we move forward with realistic proposals to address impairment from asthma. Even with reasonable practical ideas about these issues, many questions about asthma impairment remain unclear: how should impairment be assessed when should it be assessed, and what constitutes impairment? Further research and discussion will be necessary to resolve these questions.
Tags: Airway responsiveness, Asthma, bronchial responsiveness, lung function, smoking