What is the management for an infant with hyperpyrexia (extremely high fever)?

Emergency Management of Hyperpyrexia (108°F) in an Infant

This infant requires immediate emergency department evaluation with aggressive cooling measures and urgent investigation for serious bacterial infection, particularly meningitis, as temperatures ≥106°F (41.1°C) are associated with significantly higher rates of bacterial meningitis, bacteremia, and seizures. 1

Immediate Life-Threatening Priorities

Critical Assessment

• Assess for signs of shock immediately: Check for cyanosis, tachypnea, poor peripheral perfusion, petechiae, altered consciousness, or severe lethargy 2, 3
• Measure blood glucose with a glucose oxidase strip if the infant is unrousable or convulsing 4
• Document exact rectal temperature to confirm hyperpyrexia and assess for toxic appearance 5

Emergency Cooling

• Begin aggressive cooling immediately as hyperpyrexia is the most important factor causing irreversibility of shock in infants, with marked vasoconstriction increasing risk of circulatory failure and hypoxia 6
• Use paracetamol (acetaminophen) as the preferred antipyretic agent 4, 2
• Physical cooling methods (fanning, cold bathing, tepid sponging) are not recommended for routine fever but may be necessary in extreme hyperpyrexia to prevent irreversible shock 4, 6

Urgent Diagnostic Evaluation

Mandatory Investigations

Lumbar puncture is mandatory in this infant because: 4

• Infants under 12 months with fever almost certainly require lumbar puncture
• Hyperpyrexia (≥41.1°C) has significantly greater occurrence of bacterial meningitis compared to lower fevers 1
• Any infant who is unduly drowsy, irritable, or systemically ill requires CSF analysis 4

Important caveat: If the infant is comatose, an experienced physician must examine before lumbar puncture due to risk of herniation; brain imaging may be necessary first 4

Additional Required Testing

• Urinalysis via catheterization as UTI accounts for >90% of serious bacterial infections in infants aged 2 months to 2 years 5, 7
• Complete blood count and inflammatory markers (CRP, procalcitonin) 2
• Blood culture before starting antibiotics 5
• Chest radiograph if respiratory signs present (tachypnea, retractions, crackles, hypoxia) 2, 5

Treatment Algorithm

If Meningitis Suspected or Confirmed

• Start empiric antibiotics immediately after obtaining cultures 2
• Admit to hospital for intensive monitoring 2
• Continue aggressive fever management with antipyretics and ensure adequate hydration 4

If Urinalysis Positive

• Start ceftriaxone 50 mg/kg IV/IM daily after obtaining urine culture 5, 7
• Determine admission need based on clinical severity and ability to maintain oral hydration 7

If All Testing Negative

• Close observation required as the frequency of severe bacterial infection in infants under 3 months is approximately 5%, with mortality of SBI in neonates around 10% 3
• Reassessment within 24 hours is mandatory 5

Critical Red Flags

Instruct caregivers to return immediately for: 5

• Altered consciousness or severe lethargy
• Respiratory distress
• Signs of dehydration
• Persistent vomiting
• Petechial or purpuric rash
• Fever persisting ≥5 days

Key Clinical Pitfalls

• Do not delay lumbar puncture in infants under 12 months with extreme fever, as bacterial meningitis is significantly more common with hyperpyrexia 1
• Hyperpyrexia combined with circulatory impairment is more frequent in infancy due to high arterial resistance, creating marked vasoconstriction that increases shock risk 6
• The degree of parental concern is an important warning sign for serious bacterial infection and should not be dismissed 3
• Seizures are more common with hyperpyrexia; if convulsing, check blood glucose immediately 4, 1