1 Pneumology and Thoracic Surgery Service, Unit for Patients with Highly Complex COPD, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
2 University Institute of Tropical Disease and Public Health of the Canary Islands, University of La Laguna, Santa Cruz de Tenerife, Spain.
3 Pneumology Service, University Hospital Lucus Augusti, Lugo, Spain.