In: Asthma22 Jan 2013
In 1980, Bierman et al reported for the first time a late asthmatic response (LAR) after exercise challenge (EC). The LAR starts 3 to 12 hours after EC and may last for several days. According to Anderson et al, a LAR is defined as a fall in peak expiratory flow rate (PEFR) or in forced expiratory volume in 1 s (FEV^ greater than 10 percent of baseline. The prevalence of a LAR after EC has been reported to vary between 2 and 60 percent.* Recently, the existence of a LAR after EC has been challenged. These investigators looked at a LAR after EC as a nonspecific epiphenomenon, to be the result from medication withdrawal before EC, and cyclic changes in pulmonary function and airway hyperresponsiveness. It was stated in a recent review that cumulative evidence indicates that a LAR after exercise may occur, but that the prevalence of it is uncertain. buy flovent inhaler
Furthermore, decrements in airways caliber may occur simply as the result of withdrawal of medication. In a group of 86 patients with reversible airflow limitation, a LAR after EC, considered to occur when PEFR decreased by 20 percent or more on an exercise day compared with the corresponding clocktime PEFR value on a control day, was demonstrated to have a prevalence of 19 percent. In this study of Speelberg et al, it was suggested that there is no agreement in the medical literature whether the percentage of a PEFR fall after an EC should be 10 or 20 percent, depending on the spontaneous variability of PEFR in the population studied. It was also suggested that drawing graphs, instead of looking at, figures, may be more illustrative for demonstrating a LAR after EC.
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