Effective treatment for narrowed airways
Chronic obstructive pulmonary disease (COPD) is a condition where the airways become narrower and shortness of breath or dyspnoea occurs. This is usually due to pollution with noxious gases or smoking. Chronic asthma also causes airflow limitation. These are both major causes of disability due to lack of ability to exercise and carry out daily routine activities. The action of inhaled bronchodilators is to increase exercise capacity by reducing lung overinflation (or dynamic hyperinflation). However, inhalers are not found to be effective in all patients and exercise capacity can be reduced. Project partners from the Politecnico di Milano in Italy aimed to find out the reasons for this condition which can hamper a patient's recovery. A trial was conducted on 18 patients with COPD. Salbutamol and saline by inhaler were applied in a double blind randomised crossover experiment. Variables measured included forced vital capacity or the volume of air that can be forced out the lungs and functional residual capacity. Overall, this is a measure of how much air is left in the lungs after a forced exhalation. At rest and during exercise, a non-invasive method of measurement, optoelectronic plethysmography (OEP), was used to determine breathing pattern, chest wall dimensions and extent of dyspnoea. Measurements showed that the bronchodilator improved forced expiratory flow in most patients. However, in those that showed less overinflation of the lung, there was a decrease in abdominal compartmental volume which reduced their capacity to exercise. For effective treatment of COPD, an understanding of the dynamics of chest wall muscle mechanics is essential. The identification of patients with reduced exercise potential is important so therapy based on increasing chest wall capacity can be combined with the use of bronchodilators.
