1. San Pedro de Alcántara Hospital, Cáceres, Spain
2. CIBER de enfermedades respiratorias (CIBERES), Madrid, Spain
3. Virgen del Rocío Hospital, Sevilla, Spain
4. University Hospital, Burgos, Spain
5. IIS Fundación Jiménez Díaz, Madrid, Spain
6. Valdecilla Hospital, Santander, Spain
7. Gregorio Marañon Hospital, Madrid, Spain
8. Miguel Servet Hospital, Zaragoza, Spain
9. Valld'Hebron Hospital, Barcelona, Spain
10. Doce de Octubre Hospital, Madrid, Spain
11. San Juan Hospital, Alicante, Spain
12. Sleep Unit, Respiratory Department, Alava University Hospital IRB, Vitoria, Spain
13. Department of Physiology, University of Valladolid, Spain
14. Department of Medicine, Section of Pulmonary and Critical Care, University of Chicago, Chicago, IL