Background: Bronchopulmonary dysplasia (BPD) is a chronic lung disease of prematurity. The new definition of BPD was introduced in 2001. It combined two existing BPD definitions - oxygen dependency at 28 days of life and at 36 weeks of postmenstrual age. New definition divided BPD into three forms: mild, moderate and severe. Despite significant progress in neonatal intensive care and increasing survival of extremely immature infants the incidence of BPD is not decreasing. The etiopathology of new disease is still discussed.
Objective: The aim of the study was to assess the frequency and severity of BPD in very low birth weight (VLBW) neonates (<28 GA) and to determine peri- and postnatal risk factors according to the new BPD definition.
Patients and methods: We retrospectively analyzed the case records of 244 neonates boys - 112; girls - 132) at gestational age weeks 23-28 (26.4+/-1.4) treated at the Institute of Mother and Child in Warsaw between 1999 and 2004. Of these 166 (68%) infants were evaluable at 36 weeks of postmenstrual age and had BPD evaluation according to the new definition. The following variables were analyzed according to BPD status: sex distribution, gestational age, body weight at birth severity, of respiratory distress syndrome (RDS), intrauterine or late infections, congenital or late pneumonia, patent ductus arteriosus (PDA) and intraventricular haemorrhage (IVH) grade III or IV.
Results: BPD was present in 126 (76%) neonates including: severe BPD in 23 (18%), moderate 19 (15%) and mild BPD in 84 (67%) of children. Neonates with BPD had lower gestational age (26.4+/-1.3 vs 27.4+/-0.9 week, p<0.001) and lower birth weight (887+/-186 vs 1038+/-183 g, p<0.001) than children without BPD. The rates of late onset sepsis, late pneumonia and PDA were statistically higher in children with BPD than in those without BPD (respectively 70 vs 33%, 72 vs 35% and 51 vs 20% p<0.001). Logistic regression with adjustment for gestational age did not change these results. Children with severe BPD had higher rate of late infections (p<0.05) and PDA (p<0.05).
Conclusions: 1. The frequency of BPD in VLBV neonates is high (76%) but in the majority of cases the disease is mild (67%); 2. Severe BPD was more common in neonates with late onset sepsis and IVH grade III or IV; 3. The BPD risk factors are: low gestational age, low birth weight, as well as late onset sepsis, late pneumonia and PDA.