[1] Univ Med Ctr Ljubljana, Childrens Hosp, Ljubljana 1000, Slovenia
[2] Univ Ljubljana, Fac Med, Ljubljana 1000, Slovenia
[3] Hosp Sao Joao, Dept Pediat, P-4202451 Oporto, Portugal
[4] Univ Messina, Dept Pediat, I-98122 Messina, Italy
[5] Hosp Sao Joao, Paediat Sect Portuguese Soc Anaesthesiol, Dept Anesthesiol, P-4202451 Oporto, Portugal
[6] Sheffield Childrens Hosp, Inter Acad Paediat Endoscopy Training, Ctr Paediat Gastroenterol, Weston Bank, Sheffield S10 2TH, S Yorkshire, England
[7] Vrije Univ Brussel, Dept Pediat, UZ Brussel, B-1090 Brussels, Belgium