Enrico Heffler1, Silvia Fichera2, Giuliana Nicolosi2, Nunzio Crimi2. 1. Respiratory Medicine and Allergology, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy. Electronic address: heffler.enrico@gmail.com. 2. Respiratory Medicine and Allergology, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy.