Monitoring Airway Hyperresponsiveness: Pharmacological Stimuli

The role of airway challenge tests using pharmacologic stimuli in asthma has fluctuated in importance over the last 40 years. Initially proposed as diagnostic tests for asthma, they have not found widespread use in this regard. These tests remain useful in the detection of asthma in epidemiological surveys and have been included in the definition of asthma. As our knowledge of the pathology and ‘‘natural’’ history of asthma has increased and the focus of asthma treatment has gradually extended beyond days, weeks, and months to years, the use of direct challenge with pharmacologic stimuli is likely to increase. There are two reasons for this. Firstly, direct airway challenges may be useful to ensure the adequacy of current therapy and secondly, to determine the long-term efficacy of treatment, analogous to the use of the glycosylated hemoglobin in managing diabetes.