Fever in Infants and Children

Fever in Infants and Children

Fever in Infants and Children

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Fever in Infants and Children: Definition & Pathophysiology - Hot Topic Basics

  • Definition: Fever is a core body temperature ≥ 38°C (100.4°F), typically measured rectally.
  • Pathophysiology:
    • Exogenous pyrogens (e.g., microbes, toxins) stimulate release of endogenous pyrogens (cytokines: IL-1, IL-6, TNF-α).
    • Cytokines act on the hypothalamus, increasing Prostaglandin E2 (PGE2) synthesis.
    • PGE2 elevates the hypothalamic thermoregulatory set-point, leading to increased body temperature.

⭐ Rectal temperature is the gold standard for core temperature measurement in infants and young children.

Fever in Infants and Children: Etiology - Culprit Hunt Time

  • Viral Infections: Most frequent cause (e.g., URI, gastroenteritis, RSV, influenza).
  • Bacterial Infections (Serious Bacterial Infection - SBI):
    • Key concerns: UTI (esp. E. coli), pneumonia, bacteremia/sepsis, meningitis.
  • Common Bacterial Culprits by Age:
    Age GroupKey Pathogens
    Neonates (<28 d)GBS, E. coli, Listeria monocytogenes
    1-3 monthsAbove + S. pneumoniae, Hib (unimmunized)
    >3 mo - 36 moS. pneumoniae, N. meningitidis, Salmonella spp.

⭐ Most common cause of Fever Without a Source (FWS) in children <3 years is viral infection. However, Serious Bacterial Infection (SBI) must be diligently ruled out in younger infants, particularly those <3 months old (highest risk).

Fever in Infants and Children: Evaluation & Red Flags - Spotting Danger Signals

  • Evaluation: History (exposure, immunisation, sick contacts), complete exam (VS, hydration, perfusion, identify focus).
  • Red Flags: Age <3 mo (esp. <28 days), toxic appearance (📌 TICLS: Tone, Interactiveness, Consolability, Look/Gaze, Speech/Cry), Temp >40°C or <36°C (infants), petechiae/purpura, poor perfusion (cap refill >2s), cyanosis, respiratory distress, bulging fontanelle, seizures, inconsolable cry.
  • Age-Based Workup:

⭐ Any infant <28 days with fever (≥38°C) requires full sepsis evaluation (blood, urine, CSF cultures) and empiric IV antibiotics.

Fever in Infants and Children: Management - Cooling The Flames

  • Supportive care:
    • Adequate hydration.
    • Light clothing.
    • Tepid sponging (lukewarm water, avoid shivering).
  • Antipyretics:
    • Paracetamol: 10-15 mg/kg/dose (PO/PR) q4-6h. Max: 75 mg/kg/day.
    • Ibuprofen: 5-10 mg/kg/dose (PO) q6-8h for >6 months. Max: 40 mg/kg/day.

⭐ The primary goal of antipyretics is to improve child's comfort, not solely to normalize temperature; alternating antipyretics is not routinely recommended.

Fever in Infants and Children: Special Syndromes - Fever's Curveballs

  • Febrile Seizures:
    • Simple vs. Complex Criteria:
      FeatureSimple FSComplex FS
      TypeGeneralizedFocal
      Duration<15 min>15 min
      FrequencyOnce/24hMultiple/24h
      Postictal deficitNoYes
    • Rx: Antipyretics; Diazepam if prolonged.
  • Fever of Unknown Origin (FUO):
    • Definition: Fever >38.3°C for ≥3 weeks; no diagnosis after 1 week investigation.
    • Common causes: Infections (TB, typhoid), JIA, malignancy.
  • Kawasaki Disease:
    • Criteria: Fever ≥5 days (the "Burn") + ≥4 of 📌 CRASH:
      • Conjunctivitis (bilateral)
      • Rash (polymorphous)
      • Adenopathy (cervical, ≥1.5cm)
      • Strawberry tongue/lip changes
      • Hand/foot changes (edema/erythema)
    • Rx: IVIG (2g/kg), Aspirin. Kawasaki Disease Diagnostic Criteria

    ⭐ IVIG & Aspirin are crucial in Kawasaki Disease to prevent coronary artery aneurysms.

High‑Yield Points - ⚡ Biggest Takeaways

  • Fever Without Source (FWS) in infants <3 months: Always investigate thoroughly (sepsis screen).
  • Neonatal fever (<28 days): High risk of Serious Bacterial Infection (SBI); empirical antibiotics crucial.
  • Febrile seizures: Commonest 6 months to 5 years; simple vs. complex differentiation is key.
  • Kawasaki disease: Prolonged fever, rash, conjunctivitis, lymphadenopathy, mucosal changes; treat with IVIG and Aspirin.
  • Urinary Tract Infection (UTI): Common cause of FWS, especially in girls; urine culture is gold standard.
  • Roseola infantum (Exanthem subitum): High fever for 3-5 days, then rash appears as fever subsides.
  • Occult bacteremia risk significantly post-vaccination era (Hib, Pneumococcal).

Practice Questions: Fever in Infants and Children

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Simple febrile seizure is defined as

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Flashcards: Fever in Infants and Children

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The four symptoms (4S) screening for TB in children with HIV includes:Current _____FeverWeight loss or failure to gain weightHistory of _____

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The four symptoms (4S) screening for TB in children with HIV includes:Current _____FeverWeight loss or failure to gain weightHistory of _____

cough; contact with a TB case

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