Lower respiratory tract infection (Child)

🫁 Causes of Lower Respiratory Tract Infections (Children)

• 👶 Acute Bronchiolitis: Most common in infants under 2 years, usually caused by Respiratory Syncytial Virus (RSV). Classic in winter months.
• 🦠 Pneumonia: Can occur at any age; common under 5 years. Bacterial, viral, or atypical organisms may be responsible.
• 🤧 Viral LRTIs: RSV, Influenza, Parainfluenza, and Adenovirus cause milder to moderate infections but can progress in vulnerable children.
• ♻️ Chronic LRTI: Seen in children with asthma, bronchopulmonary dysplasia, or cystic fibrosis → recurrent infections, poor clearance of secretions.

🔬 Aetiology

• Viral Causes:
  • RSV → leading cause of bronchiolitis/pneumonia in infants.
  • Influenza → seasonal outbreaks, severe pneumonia possible.
  • Parainfluenza → croup, bronchitis, pneumonia in young children.
  • Human Metapneumovirus → bronchiolitis, pneumonia in infants/toddlers.
  • Adenovirus → severe pneumonia, post-infectious bronchiectasis risk.
• Bacterial Causes:
  • Streptococcus pneumoniae → lobar pneumonia, empyema risk.
  • Haemophilus influenzae type b (Hib) → rare due to vaccination, but still severe when present.
  • Mycoplasma pneumoniae → atypical pneumonia in school-age children.
  • Staphylococcus aureus → severe necrotising pneumonia, lung abscesses.
• Fungal Causes (rare, immunocompromised):
  • Aspergillus spp. → invasive disease in neutropenic children.
  • Pneumocystis jirovecii → HIV, chemotherapy, transplant patients.
• Other Factors:
  • Prematurity (underdeveloped lungs).
  • Congenital lung disease (e.g., CF, bronchopulmonary dysplasia).
  • Primary immunodeficiency or HIV.
  • Environmental → secondhand smoke 🚬, overcrowding, poor housing.

🩺 Common Symptoms

• Cough (productive or dry)
• Fever 🌡️ (low-grade to high-grade)
• Breathlessness (dyspnoea, tachypnoea)
• Pleuritic chest pain
• Wheeze or crackles on auscultation
• Fatigue, lethargy, poor feeding (infants)

👨‍⚕️ Physical Examination Findings

• Tachypnoea: earliest sign of distress 🚨
• Chest indrawing: intercostal/subcostal recession in infants
• Accessory muscle use: nasal flaring, grunting
• Abnormal breath sounds: crackles, wheeze, bronchial breathing
• Cyanosis: late, severe hypoxia → emergency sign

🧪 Diagnostic Investigations

• Chest X-ray: consolidation, effusion, hyperinflation (bronchiolitis).
• Pulse oximetry: oxygen saturation; <92% → concerning.
• Blood tests: CBC, CRP, blood cultures if sepsis suspected.
• Nasopharyngeal swabs: viral PCR (RSV, Influenza, COVID-19).
• Sputum cultures: older children if productive.

💊 Treatment Options

• Antibiotics: For bacterial pneumonia (first-line = oral amoxicillin in community).
• Antipyretics: Paracetamol/ibuprofen for fever and comfort.
• Bronchodilators: Trial in wheezy children, especially asthmatic.
• Hydration & Nutrition: IV fluids if unable to feed; monitor electrolytes.
• Oxygen therapy: If sats <92% or signs of distress.
• Hospitalisation: If severe distress, hypoxia, poor feeding, or dehydration.

⚠️ Complications

• Pleural effusion/empyema → may need drainage.
• Lung abscess (esp. Staph aureus).
• Respiratory failure requiring ventilation.
• Sepsis and multi-organ failure in severe bacterial infection.
• Post-infectious bronchiectasis (esp. adenovirus, TB, CF).

💡 Pearls: - Tachypnoea is the single most sensitive sign of pneumonia in children (WHO criteria). - RSV bronchiolitis → supportive care only (no antibiotics, no bronchodilators unless asthmatic). - Hib & pneumococcal vaccines have drastically reduced severe LRTI incidence in children.