Bronchopulmonary dysplasia: prevention, management and long-term outlook

Abstract

Despite major advances in neonatology over the last few years, neonatal intensive care units continue to care for a number of infants with ventilator and oxygen dependency or bronchopulmonary dysplasia (BPD). In 1967 Northway first described a chronic lung disease which developed after recovery from respiratory distress syndrome (RDS). 1 The original description was of a progressive illness culminating at 30 days in severe lung disease with oxygen dependency and a characteristic chest X-ray. The definition of BPD has evolved to the criteria currently used in Table 1. 36 weeks gestation is a more useful cut off when considering extremely preterm babies and is more predictive of final outcome than respiratory status at 28 days of life. The typical chest X-ray of BPD is seen in Figure 1. There are two variants which are sometimes seen in clinical practice. In the first the clinical criteria are similar but the lung appearance on chest radiograph is relatively normal or shows minor bilateral diffuse opacities. In the second the nonventilated preterm infant develops a persistent oxygen requirement commencing in the second week of life or later (Wilson Mikity syndrome). The prognosis in these two groups is better than in classical BPD. Although definitions of BPD are useful for statistics and comparisons, they are less useful clinically. BPD is more of a continuum of lung insult, injury and repair from birth. The absence of a diuresis classically present in the recovery phase of RDS, the development of pulmonary interstitial emphysema or pneumothoraces on the chest radiograph and the inability to wean the infant from the ventilator by day 7 of life are all early signs that chronic lung disease is likely to be established and the infant will continue to require respiratory support. The incidence of BPD from published studies varies considerably and is partly dependent on the definition. It varies from 3 0 4 0 % in mechanically ventilated newborns. 2~ Over the last 3 years a reduction in the number of babies with BPD on our Unit has been noted with an incidence of 15% in infants under 1500 g in 1995. Other units in the UK are reporting an increase. Good epidemiological studies are required to explain these differences.