1. Thoracic Surgery Department, Laboratory of Airways and Lung, Hospital of Clínicas of Porto Alegre, Ramiro Barcelos 2.350, 90035-903 Porto Alegre, RS, Brazil
2. Federal University of Rio Grande of Sul (FRGS), Rua Ramiro Barcelos 2400, 2° andar Bairro Santana, 90035-003 Porto Alegre, RS, Brazil