1. Haemophilia Centre; Haemostasis and Thrombosis Unit; Aghia Sophia Children's Hospital; Athens Greece
2. ENT department; Aghia Sophia Children's Hospital; Athens Greece
3. Department of Thoracic Surgery; Sotiria Chest Diseases Hospital; Athens Greece
4. 1 Paediatric Department; Athens Medical School; Aghia Sophia Children's Hospital; Athens Greece