Nitric Oxyde Concentration in Chronic Obstructive Pulmonary Disease Patients - SANOB Study

* Among many other causes, Bronchial obstruction in Chronic Obstructive Pulmonary Disease (COPD) is also caused by inflammation of peripheral airways walls. * Neutrophils and other inflammatory mediators like Interleukin-6 (IL6), Interleukin-8 (IL8), Interleukin-1 alpha (IL-1 alpha),Interleukin-1beta (IL-1 beta), Tumor Necrosis Factor alfa (TNF-alfa), Reactive Oxygen Species (ROS), Leukotriene B4 (LTB4), Nitric Oxyde (NO) are implicated in the inflammation. * NO is produced in response to physical and chemical stress on bronchial epithelium and plays a critical role in small airways remodelling * Exhaled NO concentration is usually used to monitor bronchial inflammation * The relationship between stretch and strain of small airways and bronchial inflammation is not well understood. * The investigators hypothesis is that cyclic opening and closure of peripheral obstructed airways through the consequent stretching and strain acting on them can provoke an inflammatory response which can be monitored by exhaled NO. * The pharmacological effects of bronchodilators may play a role on bronchial inflammation by reducing the stretching stress on bronchiolar walls thus reducing the production of NO in exhalate * Data about these physiopathological aspects is missing in literature.