Seminars in respiratory and critical care medicine
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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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Severe asthma affects 5 to 10% of the asthma population but consumes a disproportionate amount of the global asthma budget (~50%) due to unscheduled health care utilization in primary care, hospitalizations due to severe exacerbations, and the costs of pharmacotherapy. A key challenge in managing severe asthma is to identify appropriate groups of patients that will respond best to existing and evolving therapies. Recent advances in our understanding of how to classify severe asthma using multivariate taxonomical approaches have provided a unique model of a stratified medicines approach. ⋯ A similar paradigm can be applied to other domains in severe asthma such as airway hyperresponsiveness, which may now be treated with the first mechanical therapy in airways disease (bronchial thermoplasty). At the same time it is important for the clinician to recognize and treat comorbid factors that make asthma difficult to manage such as poor adherence to medication, rhinosinusitis, and psychological comorbidity. Therefore it is of vital importance to develop a multidisciplinary approach to the management of severe asthma that is best applied within specialist centers with experience and wider access to national and international severe asthma networks.
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Semin Respir Crit Care Med · Dec 2012
Aspirin-exacerbated respiratory disease: update on pathogenesis and desensitization.
Aspirin-exacerbated respiratory disease (AERD) is a unique syndrome of airway inflammation that frequently occurs in patients with nasal polyposis, chronic sinusitis, and asthma. These patients tend to have progressive and recalcitrant sinus disease requiring frequent surgical intervention and in many cases systemic corticosteroids. Much about the pathogenesis of AERD remains unclear, but environmental factors likely play a prominent role in its development. ⋯ Given the prevalence and usefulness of aspirin and NSAID therapy in primary care clinics, an accurate diagnosis should be made in all patients. Desensitization is an effective treatment option for many patients. Recent advances have made this procedure considerably safer and outpatient aspirin desensitization is now the standard of care.
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The identification of phenotypes of asthma has a long history, but previous classifications have not identified clinically important differences in pathology, natural history, or treatment response. Progress has accelerated recently, fueled by the development of new techniques to assess airway disease, particularly noninvasive techniques to assess airway inflammation. ⋯ There has been increasing interest in the application of mathematical techniques such as factor analysis and cluster analysis to organize and group large amounts of interrelated data in an unbiased way. This article discusses attempts to do this in asthma and speculates on the clinical implications of this new information.
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Semin Respir Crit Care Med · Dec 2012
Asthma: vocal cord dysfunction (VCD) and other dysfunctional breathing disorders.
Vocal cord dysfunction (VCD) and dysfunctional breathing (DB) disorders may mimic or coexist with asthma, leading to overtreatment with corticosteroids with consequent morbidity. Iatrogenic complications can be averted by early and correct diagnosis. VCD, also termed paradoxical vocal fold motion disorder (PVFMD), is characterized by intermittent paradoxical adduction of the vocal cords, mainly during inspiration, leading to airflow obstruction and dyspnea. ⋯ The pathophysiology of DB is poorly understood, but psychological or physiological stress may precipitate episodes in some patients. Treatment requires a multidisciplinary approach (including speech therapy and psychological support). Prognosis is usually good.