1. Respiratory Department, Hospital de la Santa Creu I Sant Pau, 08041 Barcelona, Spain
2. Respiratory Department, Hospital de Bellvitge, 08907 L’Hospitalet de Llobregat, Spain
3. Respiratory Department, Hospital Clínic i Provincial, 08036 Barcelona, Spain
4. Respiratory Department, Hospital Lucus Augusti, 27003 Lugo, Spain
5. Respiratory Department, Hospital de la Princesa, 28006 Madrid, Spain
6. Respiratory Department, Hospital La Fe, 46026 Valencia, Spain