Central sleep apnoea and hypoventilation syndromes — formative SAQs

SAQ 1 — The neonate who breathes awake but not asleep (10 marks, 15 minutes)

A term newborn boy is well and pink while awake and handling, but during sleep he becomes shallow-breathing, cyanosed and desaturates, with a rising carbon dioxide on blood gas. Echocardiography and chest imaging are normal and the lungs are clear. He repeatedly fails attempts to wean from respiratory support. There is a history of severe constipation since birth. ^[1]

a) What is the most likely diagnosis, and what single feature of the history and examination pattern points to a central disorder of the control of breathing rather than a cardiac or pulmonary cause? (3 marks) ^{[1] [3]}

b) What confirmatory investigation would you send, and what does it tell you about severity and associated risks? (3 marks) ^{[1] [15]}

c) Outline the immediate ventilatory principle that protects this baby and why supplemental oxygen alone is dangerous. (4 marks) ^[1]