HERMES Paediatric Respiratory cheat sheet

Paediatric Respiratory Medicine - Core Facts and Decision Rules

• Normal infant respiratory rate: newborn 30–60/min, falling to 20–30/min by 12 months; tachypnoea thresholds used by WHO for pneumonia are ≥60/min under 2 months, ≥50/min at 2–11 months, ≥40/min at 12–59 months.

• Oxygen saturation targets: 94–98% for most acute paediatric respiratory illness; in bronchiolitis a threshold of <92% is commonly used to start supplemental oxygen, and saturations alone are a poor discharge criterion because they dip in sleep.

• Croup (laryngotracheobronchitis): barking cough, hoarse voice, inspiratory stridor; graded mild/moderate/severe. Dexamethasone 0.15–0.6 mg/kg single dose (oral/IM/IV) treats all grades; nebulised adrenaline 1:1000, 0.5 mL/kg (max 5 mL) is for moderate-severe or impending airway failure with reassessment after 20–30 minutes.

• Bronchiolitis: viral (RSV most common), peak age 2–6 months, prodromal coryza then tachypnoea, wheeze/crackles, feeding difficulty. Management is supportive - oxygen if saturations low, nasogastric or IV fluids if feeding <50–75% of normal, suction of secretions; bronchodilators, corticosteroids, antibiotics and chest physiotherapy are not routinely indicated.

• Asthma severity in acute attacks is graded on ability to talk, heart rate, respiratory rate, oxygen saturation and peak expiratory flow. Life-threatening features: silent chest, cyanosis, poor respiratory effort, exhaustion, hypotension, altered consciousness, PEF <33% predicted. Give oxygen, repeated inhaled beta-2 agonist (with ipratropium in severe/life-threatening), systemic corticosteroids, and IV magnesium sulfate 40–50 mg/kg (max 2 g) over 20 minutes in severe/life-threatening attacks not responding to initial therapy.

• Preschool wheeze: episodic viral wheeze versus multiple-trigger wheeze. Inhaled corticosteroids are indicated for multiple-trigger or frequent troublesome wheeze; a trial (e.g. 3 months) with objective review is preferred to indefinite therapy, and montelukast is an alternative add-on.

• Cystic fibrosis diagnosis: positive newborn screening (raised immunoreactive trypsinogen) or clinical suspicion, then sweat chloride testing - ≥60 mmol/L diagnostic, 30–59 mmol/L intermediate (repeat, genetic testing, extended testing), <30 mmol/L normal in infants. Two disease-causing CFTR mutations or abnormal nasal potential difference also confirm diagnosis.

• Foreign body aspiration: sudden onset cough/choking in a previously well child, unilateral reduced breath sounds or wheeze, may have normal examination. Suspected inhaled foreign body with respiratory distress needs urgent rigid bronchoscopy; plain films are normal in a substantial minority because most aspirated objects are radiolucent (food, plastic).

• Tuberculosis in children: usually paucibacillary and smear-negative, so diagnosis rests on contact history, tuberculin skin test/interferon-gamma release assay, chest radiograph (hilar lymphadenopathy, miliary pattern) and gastric aspirate or induced sputum for culture/PCR. Children under 10 with latent infection are usually treated with 3 months of isoniazid plus rifampicin (or 6 months isoniazid monotherapy).