Bronchopulmonary dysplasia (BPD) is defined by the NIH as mild, moderate, or severe based on the required respiratory support at 36 weeks adjusted age. 1 An NIH workshop proposed a severity-based definition that classifies BPD into mild, moderate or severe based on either postnatal age or PMA (Table 2-1). Mild BPD was defined as a need for supplemental oxygen {02) for~ 28 days but not at 36 weeks PMA or discharge, moderate BPD as 0 2 for~ 28 days plus treatment with <30% 0 2 at 36 weeks PMA, and severe BPD as 0 2 for~ 28 days plus~ 30% 0 2 and/or positive pressure at 36 weeks PMA. Ehrenkranz et af validated the NICHD severity-based definition ofBPD by comparing it to the more traditional definitions ofBPD such as supplemental oxygen at 28 days and at 36 weeks PMA. The NICHD consensus severity based scale better identified infants who are at most risk for poor pulmonary outcomes as well as neurodevelopment impairment than the traditional definitions
