Lesson of the Week: Pulmonary hypoplasia presenting as persistent tachypnoea in the first few months of life

CASE 1

This boy was born by normal delivery at 39 weeks' gestation after an uneventful pregnancy; he weighed 2960 g. He was seen on the postnatal ward at 12 hours of age for grunting and poor feeding. A chest x ray taken at the time was consistent with transient tachypnoea of the newborn. He was discharged at 5 days of age but remained tachypnoeic. At 3 weeks of age he was admitted with fever and coryzal symptoms, pronounced tachypnoea, and poor feeding. Examination was unremarkable apart from a respiratory rate of 70/minute with mild intercostal recession.

The coryzal illness resolved but he continued to be tachypnoeic. An electrocardiogram and an echocardiogram did not disclose any abnormalities. He was referred for lung function testing at the age of 4 months because of parental anxiety. His functional residual capacity measured by whole body plethysmography was 16.9 ml/kg indicating pulmonary hypoplasia. In our laboratory the normal mean is 29.8 ml/kg (range 17.6-42 ml/kg). Over the first year his respiratory rate gradually settled to 30-35/minute at rest. A repeat measurement at 12 months of age was 20 ml/kg, showing “catch up” lung growth.

CASE 2

Born …