| Popis: |
Concern has been expressed about rising asthma morbidity and mortality, although the latter appears to have declined recently. A reasonable surrogate for fatal asthma is an episode of near fatal asthma (NFA). The etiology of episodes of NFA appears to be multifactorial. Features that would characterize asthma patients at risk of NFA have been difficult to define but have included psychosocial barriers. environmental exposures, inadequate or inappropriate physician and/or patient responses to deteriorating asthma and, in particular, overreliance on symptomatic bronchodilator therapy. The association between fatal asthma and NFA with beta-agonist use has been controversial, with it being argued that high use of beta-agonists reflects severity of asthma as opposed to being causal. Studies in the laboratory and ambulatory care setting suggest that regular compared with as-required use of beta-agonists is associated with worsening in asthma control. Although a reduced perception of dyspnea has been identified in some asthma patients, it is not universally present in those with NFA. Retrospective data suggest that hyperinflation of the thorax, as judged by total lung capacity, may be a useful marker for subjects at risk of NFA. Future studies should better characterize these risk factors and develop management strategies (both therapeutic and educational) that might reduce the risk of subjects experiencing episodes of NFA and, by extension, reducing the continued unacceptable mortality associated with asthma. |
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