Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Dec 2012
ReviewThe role of air pollution in adult-onset asthma: a review of the current evidence.
The causes of adult-onset asthma are poorly established, and the asthmogenic role of air pollution has been investigated primarily in children. This review assesses the current evidence of the association between air pollution and asthma incidence among subjects free of asthma at least until late childhood. Seven publications from five study populations fulfilled the inclusion criteria (one case-control and six cohort studies). ⋯ Larger studies with more consistent definitions of phenotypes and exposure assessment for local traffic-related pollutants (e.g., ultrafine particles) are needed. Pooling existing cohorts such as in the ongoing European ESCAPE and TRANSPHORM consortia are promising steps. There is, however, a need for large-scale megacohorts to investigate these effects in standardized ways and to identify the most susceptible populations.
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Asthma is a chronic inflammatory condition affecting up to 10% of all women of child-bearing age. In most patients asthma can be safely treated during pregnancy. However, asthma crises or exacerbations during pregnancy can be life threatening to both the mother and the child. ⋯ Pregnant asthmatics require regular and intensified monitoring. National and international guidelines recommend that antiasthmatic treatment should be maintained and intensified if necessary for the well-being of both the mother and the unborn child. Although there is consensus that the potential risks of uncontrolled asthma during pregnancy outweigh the potential risks of antiasthmatic medications the use of the lowest doses possible to achieve and maintain asthma control is recommended.
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Asthma is a heterogeneous disease, with wide variability in pathology, natural history, and response to therapy. Historically, treatment of asthma relied almost exclusively on clinical judgment and pulmonary function tests (spirometry or peak flows), despite the limitations of both. Physiological tests are one step removed from what the clinician needs to know, namely, the underlying activity and whether it is amenable to additional or alternative treatment. ⋯ Financial constraints applied by health providers and funding agencies have limited the use of induced sputum analysis and exhaled nitric oxide to date. However, evaluation of candidate biomarkers has provided important insights in clinical practice and in research settings. At the very least, existing techniques should have a regular place in severe asthma clinics, if not more widely, where heterogeneity is the norm and not all asthma is what it seems.
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Population-based studies suggest that one in 10 cases of new, recurrent, or deteriorating asthma in adulthood is related to the workplace environment. Nonspecific, irritant exposures at work can upset symptom control in pre-existing disease (work-exacerbated asthma); where disease arises de novo from the workplace (occupational asthma) it generally has an allergic basis, arising from airborne exposure to a sensitizing agent. ⋯ The majority of cases can be diagnosed through a combination of a careful history, appropriate immunology (where available), and the detection of work-related variability in measurements of lung function made serially at work and at home. Occupational asthma is a disease that is potentially preventable and often curable; positive outcomes are dependent more on changes in the workplace than on pharmacological therapy.
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Semin Respir Crit Care Med · Dec 2012
ReviewAirway hyperresponsiveness: new insights into the pathogenesis.
Airway hyperresponsiveness (AHR) is the most characteristic clinical feature of asthma. The pathogenesis of AHR in asthma is characterized by a variety of epithelial, microbial, and inflammatory triggers on one hand and abnormalities of effector structures in the airways such as smooth muscle cells, blood vessels, and nerves on the other hand. ⋯ This may be one reason for the observation that potent new antiinflammatory drugs for the treatment of asthma have only little impact on AHR. New therapeutic strategies are, therefore, needed to modulate structural and functional changes in the airways, especially in patients with treatment-resistant severe asthma.