Clinics in chest medicine
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Clinics in chest medicine · Mar 2014
ReviewChronic obstructive pulmonary disease: clinical integrative physiology.
Peripheral airway dysfunction, inhomogeneous ventilation distribution, gas trapping, and impaired pulmonary gas exchange are variably present in all stages of chronic obstructive pulmonary disease (COPD). This article provides a cogent physiologic explanation for the relentless progression of activity-related dyspnea and exercise intolerance that all too commonly characterizes COPD. ⋯ Also explored are the perceptual and physiologic consequences of progressive erosion of the resting inspiratory capacity. Finally, emerging information on the role of cardiocirculatory impairment in contributing to exercise intolerance in patients with varying degrees of airway obstruction is reviewed.
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Alpha1-antitrypsin (AAT) deficiency was first described in 1963 together with its associations with severe early-onset basal panacinar emphysema. The genetic defects leading to deficiency have been elucidated and the pathophysiologic processes, clinical variation in phenotype, and the role of genetic modifiers have been recognized. ⋯ The only recognized specific therapeutic strategy is regular infusions of the purified plasma protein, and evidence confirms its efficacy in protecting the lung (at least partially). Early detection and modification of lifestyle remains crucial to the management of AAT deficiency.
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As parenchymal lung disease in chronic obstructive pulmonary disease becomes increasingly severe there is a diminishing prospect of drug therapies conferring clinically useful benefit. Lung volume reduction surgery is effective in patients with heterogenous upper zone emphysema and reduced exercise tolerance, and is probably underused. Rapid progress is being made in nonsurgical approaches to lung volume reduction, but use outside specialized centers cannot be recommended presently. Noninvasive ventilation given to patients with acute hypercapnic exacerbation of chronic obstructive pulmonary disease reduces mortality and morbidity, but the place of chronic non-invasive ventilatory support remains more controversial.
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Chronic obstructive pulmonary disease (COPD) is currently defined as a common preventable and treatable disease that is characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. Exacerbations and comorbidities contribute to the overall severity in individual patients. The evolution of this definition and the diagnostic criteria currently in use are discussed. COPD is increasingly divided in subgroups or phenotypes based on specific features and association with prognosis or response to therapy, the most notable being the feature of frequent exacerbations.
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Cigarette smoking is a major preventable cause of morbidity and mortality. It is the major risk factor for chronic obstructive pulmonary disease in the developed world. Smoking is a chronic relapsing disease. ⋯ All clinicians should be comfortable with the use of nicotine replacement therapy, bupropion, and varenicline. Second-line therapies can be used by those familiar with their use. Effective use of these medications requires their integration into an effective management plan, which is likely to be a long-term undertaking, involving several cycles of remission and relapse.