Paediatric Cardiology and Pulmonology
This domain tests whether you can separate an innocent murmur from a pathological one, recognise a duct-dependent circulation before collapse, and manage the two commonest respiratory emergencies of childhood, croup and bronchiolitis, without overtreating.
Murmurs and the neonatal circulation
- Innocent murmurs are soft, systolic, short, vary with position and are not accompanied by clicks, thrills, cyanosis, poor feeding or failure to thrive.
- Any murmur with a diastolic component, a click, a loud single second sound, weak femoral pulses or a syndromic feature needs echocardiography.
- Duct-dependent lesions: prostaglandin E1 keeps the duct open in critical coarctation, interrupted arch, pulmonary atresia and transposition; watch for apnoea as a side effect.
- Critical congenital heart disease screening by pre- and postductal pulse oximetry at 24-48 hours; a difference of more than 3% or a saturation below 95% triggers echocardiography.
Cyanotic spells and arrhythmia
Tetralogy spell: knee-chest position, oxygen, morphine, intravenous fluid, beta-blocker, and phenylephrine if refractory. Supraventricular tachycardia in an infant: vagal manoeuvre, then adenosine 0.1 mg/kg rapid intravenous push, then synchronised cardioversion.
Respiratory disease
- Croup: barking cough, stridor, hoarse voice; a single dose of oral dexamethasone, nebulised adrenaline only for moderate to severe obstruction.
- Bronchiolitis: supportive care, oxygen for saturations below 90-92%, feeding support; no routine bronchodilators, steroids or antibiotics.
- Asthma: stepwise inhaled corticosteroid treatment, salbutamol for acute symptoms, and a written action plan. Diagnosis in a wheezing infant is unreliable; most preschool wheeze is not asthma.
- Cystic fibrosis: sweat chloride above 60 mmol/L, newborn screening, pancreatic enzyme replacement.
Worked example
A 3-week-old has poor feeding, tachypnoea, weak femoral pulses and a systolic blood pressure 20 mmHg higher in the arms than the legs. This is coarctation until proven otherwise. Start prostaglandin E1, keep oxygen and ventilation cautious, and arrange urgent echocardiography; do not wait for a murmur.
Traps
Reassuring a family because a saturation is 97% when femoral pulses were never felt; giving antibiotics for bronchiolitis; diagnosing asthma in a 9-month-old with recurrent wheeze; using nebulised adrenaline as routine croup treatment.