MCQ Bank

A previously well 2-week-old term infant presents with poor feeding and pallor. Heart rate is 290 bpm. After the first 20 beats, the R-R interval is extremely regular. P waves are visible in 60% of the complexes and differ in morphology from the sinus P waves recorded on a previous ECG. The QRS morphology is identical to that during sinus rhythm. Which is the single most likely diagnosis?

A male infant is delivered at 39 weeks gestation following an antenatally diagnosed left-sided congenital diaphragmatic hernia. He develops severe hypoxaemia within the first hour of life with marked respiratory distress. Echocardiography confirms a structurally normal heart with severely raised pulmonary vascular resistance and right-to-left ductal shunting. Which is the single most likely underlying mechanism of his persistent pulmonary hypertension?

A baby boy is born at 26 weeks' gestation. He is breathing spontaneously and is stabilised on CPAP shortly after birth, with the team using a blended oxygen supply. They wish to titrate the inspired oxygen to an evidence-based starting concentration. According to the 2025 European Consensus Guideline on RDS, what is the most appropriate starting FiO₂ for this infant?