[1] Hosp Sao Joao, Dept Pediat, Serv Neonatol, Div Neonatol, P-4202451 Oporto, Portugal
[2] Hosp Sao Joao, Dept Pediat, Unit Pediat Pulmonol, P-4202451 Oporto, Portugal
[3] Hosp Sao Joao, Dept Pediat, Div Pediat Surg, P-4202451 Oporto, Portugal
[4] Univ Porto, Fac Med, Oporto, Portugal
[5] Univ Minho, Sch Hlth Sci, P-4719 Braga, Portugal