1. Pediatric Thoracic Surgery Unit/Pediatric Surgery Service; Hospital de Clínicas de Porto Alegre; Department of Surgery; School of Medicine, Federal University of Rio Grande do Sul; Porto Alegre RS Brazil
2. Department of Otology and Laryngology; Harvard Medical School; Boston Children's Hospital; Boston Massachusetts U.S.A
3. Department of Otolaryngology and Communication Enhancement; Boston Children's Hospital; Boston Massachusetts U.S.A
4. Department of Otolaryngology-Head and Neck Surgery; Johns Hopkins University; Baltimore Maryland
5. Department of Surgery; Boston Children's Hospital; Boston Massachusetts U.S.A