Airway Obstruction in Severe COPD

Lung obstruction in emphysema patients is due to the reduction of airway support and the consequent dynamic collapse of airways, particularly during forced exhalation; in emphysema patients, intrinsic airway disease is not present and resistance is entirely expiratory. Severe COPD is a combination of emphysema with varying amounts of chronic bronchitis and bronchospasm. The primary treatment for chronic or recurrent bronchospasm is administration of anti-inflammatory drugs, specifically, inhaled corticosteroids. Attempts to identify significant responses to inhaled steroids in patients with moderate COPD have shown minor improvement in pulmonary function utilizing forced exhalation and in functional measures determined using such assessment tools as questionnaires or distance walked in 6 min. It is usually stated that patients with more severe, end-stage disease will not benefit from receiving inhaled corticosteroids. Canadian health care mall online

The possible reasons for such negative opinions about corticosteroids in patients with severe COPD include the following: (1) minimum or the wrong type of airway inflammation; (2) ineffective delivery of inhaled drugs to the sites of inflammation in the airway; and (3) utilization of the wrong evaluation measures. However, (1) airway inflammation clearly plays a role in COPD, since oral corticosteroids are often the sole effective treatment for acute exacerbations of COPD. (2) The delivery of inhaled drugs to airways remains a major issue. The proper use of metered-dose inhalers is not intuitive, and, even with coaching, the coordination of activation with inhalation, the slow speed of inhalation, and end-expiratory breath holding are rarely achieved.

Spacers, dry-powder inhalers, and breath-activated devices help with the coordination, but a too-rapid inhalation speed remains a common limitation. (3) The pulmonary function response to agents that increase airway diameter can be accurately assessed with the use of the body plethysmograph, but use of this tool is limited to specialized laboratories. Functional assessments such as the 6-min walking test may be faulty guides to the improvement of airway caliber in patients with COPD, since patients with severe COPD are limited by physical deconditioning and can greatly improve conditioning by pulmonary rehabilitation without change in pulmonary function (by all measures, including body plethysmography). – click to go to main page blog in Canada.