Using published diagnostic criteria, how would you classify the severity of bronchopulmonary dysplasia in an infant at 8 weeks postnatal age requiring 28% oxygen?

• A. Mild
• B. Moderate
• C. Severe
• D. Not BPD

Answer: (B)

Bronchopulmonary dysplasia severity is determined by the infant’s oxygen needs at around 36 weeks postmenstrual age. If still on oxygen, the level of FiO2 separates mild, moderate, and severe: less than 30% oxygen indicates moderate BPD, while 30% or more (or need for positive-pressure support) indicates severe. In this case, being on 28% oxygen at 8 weeks postnatal age places the infant in the moderate category, assuming the PMA is around 36 weeks. If oxygen had been discontinued by 36 weeks PMA, it would be mild; if the oxygen need were ≥30% or there was ventilatory support, it would be severe. Not BPD would apply only if no oxygen was required after 28 days.