Apnoea of prematurity — structured oral (viva)

Branch 1 — Definition and classification

Examiner: "What is apnoea of prematurity, and how do you define an event?" Candidate: Apnoea of prematurity is a developmental disorder of respiratory control in infants born before 37 weeks, presenting after the first 24 hours. An event is defined as a cessation of breathing for 20 seconds or longer, or a shorter pause with bradycardia below 80 beats per minute, central cyanosis, or desaturation below 80 to 85 percent. [2]

Examiner: "Name the three types. Which is most common?" Candidate: Central apnoea is absent effort and airflow from loss of neural drive; obstructive apnoea preserves effort but loses airflow through upper-airway collapse; and mixed apnoea is a central pause followed by obstruction. Mixed is the most common type, which is why continuous positive airway pressure is often required alongside caffeine. [2]

Branch 2 — Interpretation of the change

Examiner: "The events have tripled over 12 hours. What does that tell you, and what will you do first?" Candidate: A worsening pattern after a period of stability is a sentinel for late-onset sepsis or necrotising enterocolitis until proven otherwise. My first step is a septic screen — blood culture, full blood count and CRP — and I would start broad-spectrum antibiotics. I would also check a blood gas, glucose, and electrolytes, and examine the abdomen. [2]

Branch 3 — Pharmacology

Examiner: "Tell me about caffeine. What is the mechanism and the dosing?" Candidate: Caffeine is the methylxanthine of choice. It antagonises adenosine A1 and A2a receptors, increasing central respiratory drive, sharpening the response to carbon dioxide, and improving diaphragmatic contractility. I would give caffeine citrate as a loading dose of 20 mg/kg followed by maintenance of 5 to 10 mg/kg once daily. The Caffeine for Apnea of Prematurity trial confirmed that this strategy improved survival without neurodevelopmental disability at 18 to 21 months. [1]

Examiner: "Why caffeine over theophylline?" Candidate: Caffeine has a wider therapeutic index, once-daily dosing, faster onset, and fewer side effects; theophylline requires serum-level monitoring that caffeine does not. Cochrane review confirms caffeine is preferred over theophylline for apnoea in preterm infants. [1]

Branch 4 — Escalation and prognosis

Examiner: "If caffeine and antibiotics are running but the infant continues to desaturate, what next?" Candidate: I would add nasal continuous positive airway pressure or nasal intermittent positive-pressure ventilation to splint the upper airway and maintain functional residual capacity, addressing the obstructive component. If apnoea remains refractory, doxapram infusion is the third-line rescue agent. [2]

Examiner: "What do you tell the family about long-term outlook?" Candidate: Most infants outgrow apnoea of prematurity by 36 weeks postmenstrual age, with resolution by 43 to 44 weeks in the extremely preterm. Apnoea of prematurity is not a risk factor for sudden infant death syndrome, and home monitoring is not routinely indicated. [2]