Emergency Management of Heat Stroke in a 5-Month-Old Infant
Immediately initiate rapid active cooling with cool water spray and fan evaporation while simultaneously supporting circulation with volume expanders, as cold-water immersion—though the gold standard for older patients—is often impractical and potentially dangerous in infants this young.
Immediate Recognition and Assessment
The diagnosis requires three cardinal features 1:
- Hot, dry skin (though infants may still have some moisture)
- Central nervous system disturbance (altered mental status, lethargy, irritability, or seizures)
- Hyperpyrexia (core temperature typically >40°C)
In infants, heat stroke typically results from excessive environmental temperature and/or dehydration rather than exertion 1. Common scenarios include being left in hot vehicles or overdressing in warm environments.
Primary Treatment: Rapid Cooling
Cooling Method Selection
While the 2025 Society of Critical Care Medicine guidelines establish cold-water immersion as the preferred modality for heat stroke 2, practical considerations in a 5-month-old infant necessitate alternative approaches:
Recommended approach for infants:
- Evaporative cooling: Spray the infant with cool (not ice-cold) water and position fans to blow air across the body 3
- Remove all clothing immediately
- Apply cool, wet towels to the body, replacing them frequently
- Focus cooling on high-perfusion areas (axillae, groin, neck)
Why not cold-water immersion in this age group?
- Logistical challenges with maintaining airway and monitoring in a small infant
- Risk of rapid overcooling and hypothermia due to high body surface area-to-mass ratio
- Difficulty maintaining vascular access
- Impaired ability to monitor vital signs and neurologic status
Cooling Targets and Duration
- Target temperature: 38.6°C (101.5°F) core temperature 2, 4
- Time goal: Achieve target within 30 minutes if possible 2
- Cooling rate: Aim for ≥0.155°C/min 2
- Critical principle: The faster the cooling, the lower the mortality 5, 6
Monitor core temperature continuously using rectal thermometry (most accurate in infants). Stop active cooling at 38.6°C to prevent overshoot hypothermia.
Simultaneous Supportive Care
Circulatory Support
Immediately establish IV/IO access and administer volume expanders 1:
- Infants with heat stroke are typically significantly dehydrated
- Start with 20 mL/kg bolus of isotonic crystalloid (normal saline or lactated Ringer's)
- Reassess perfusion and repeat as needed
- Monitor for signs of fluid overload given risk of multiorgan dysfunction
Airway and Breathing
- Assess and secure airway if mental status is significantly depressed
- Provide supplemental oxygen
- Prepare for intubation if Glasgow Coma Scale deteriorates or seizures are refractory
Anticipate and Manage Complications
Heat stroke causes multiorgan dysfunction 1, 7. Be prepared to address:
Neurologic:
- Seizures (treat with benzodiazepines)
- Cerebral edema (consider hypertonic saline if signs of increased ICP)
Hematologic:
- Disseminated intravascular coagulation (monitor PT/PTT, fibrinogen, D-dimer)
- Obtain baseline coagulation studies
Renal:
- Acute kidney injury from rhabdomyolysis and direct heat injury
- Monitor urine output, electrolytes, creatinine
- Maintain adequate urine output with fluid resuscitation
Hepatic:
- Transaminitis and hepatic dysfunction
- Check liver function tests
Metabolic:
- Hypoglycemia (check glucose immediately in all infants)
- Electrolyte abnormalities (particularly hypernatremia from dehydration)
Critical Pitfalls to Avoid
Delayed cooling: Every minute counts. Start cooling measures immediately—do not wait for laboratory confirmation or imaging 6
Antipyretics are ineffective: Do NOT waste time administering acetaminophen or ibuprofen. Heat stroke is a failure of thermoregulation, not a fever 7
Overcooling: Stop active cooling at 38.6°C. Infants can rapidly become hypothermic due to their high surface area-to-mass ratio
Inadequate fluid resuscitation: Infants with heat stroke are profoundly volume depleted and require aggressive fluid replacement 1
Failure to monitor core temperature: Peripheral or axillary temperatures are unreliable. Use rectal temperature monitoring
Disposition
All infants with heat stroke require ICU admission for:
- Continuous cardiorespiratory monitoring
- Serial neurologic assessments
- Management of multiorgan dysfunction
- Temperature monitoring to prevent rebound hyperthermia 7
The prognosis depends critically on the rapidity of cooling initiation and the duration of hyperthermia 5, 6. Residual brain damage is a significant risk, particularly if cooling is delayed 1.