Cyanotic newborn and critical congenital heart disease screening — branching viva

Opening question

A thirty-hour-old term infant is dusky on feeding but comfortable, with SpO₂ of 86 per cent in the right hand and 84 per cent in the foot in air and no murmur. Interpret the screen against the thresholds, and tell me your immediate next step and your immediate management. [2] [9]

Branch 1 — the well-looking blue baby

The baby looks well and the team wonders whether the saturation can be watched. Why does the appearance not lower your concern, which bedside findings localise a cardiac lesion, and why is the absence of a murmur a trap rather than a reassurance? [2]

Branch 2 — oxygen and the duct

The team asks whether to give 100 per cent oxygen while waiting. Explain the principle that governs oxygen in a suspected duct-dependent mixing lesion, name the drug that reopens the duct, its starting dose range, and why it must precede the echocardiogram. [9] [8]

Branch 3 — the differential and the hyperoxia test

The baby has a metabolic acidosis and a septic screen is sent. Discuss the differential diagnosis of neonatal cyanosis, the interpretation and the limits of the hyperoxia test, and the investigation that settles cardiac versus pulmonary disease. [2]

Branch 4 — the collapsed infant and the screening failure

Now picture the same lesion missed and the baby collapsing at home at forty-eight hours. Explain why this is a failure of the layered screening programme, and describe the three layers that should have detected the lesion and why each can miss. [1] [2]

Closing — the principle in one sentence

In one sentence, what is the prostaglandin-first principle of the cyanotic newborn, and why does the general paediatrician's speed to reopen the duct matter more than the speed of the diagnosis? [8] [1]