Spectrum from heat cramps to heat stroke. Heat stroke = T > 40 °C with CNS dysfunction — life-threatening, rapid cooling within 30 min reduces mortality. Children at higher risk due to higher surface area:mass ratio and immature thermoregulation.
🚩 Red-flag clues (must not miss)
- •T > 40 °C + altered mental status = heat stroke — cool aggressively NOW
- •Anhidrosis is a LATE finding; sweating may persist in exertional heat stroke
- •Rhabdo + AKI + DIC + multiorgan failure if cooling delayed
- •Child left in car — consider in summer AMS / arrest
History
- Activity, environmental temp/humidity, fluid intake
- Medications (anticholinergics, stimulants, antipsychotics)
- Fever vs hyperthermia (heat stroke does not respond to antipyretics)
Exam
- Core (rectal or esophageal) temp — skin temp unreliable
- Mental status, seizures, posturing
- Skin: hot, may be wet (exertional) or dry (classic)
Labs
- BMP, CK, LFTs, coags, fibrinogen, lactate, UA (myoglobin), troponin
Differential & next step
| Diagnosis | Clue | Next step |
|---|---|---|
| Heat cramps | Muscle cramps, normal mental status, normothermic-mild ↑ | Oral electrolytes, rest, cool environment |
| Heat exhaustion | T 37–40 °C, normal mental status, dehydrated | Cool, IV NS, oral hydration |
| Heat stroke (classic) | T > 40 °C, AMS, anhidrosis, elderly/young | Aggressive cooling, ICU |
| Heat stroke (exertional) | T > 40 °C, AMS, athlete, may sweat | Cold-water immersion = fastest cooling |
| Malignant hyperthermia | Anesthetic exposure, masseter rigidity | Dantrolene 2.5 mg/kg IV q5min |
| NMS | Antipsychotic, lead-pipe rigidity | Stop offender; bromocriptine, dantrolene |
| Serotonin syndrome | SSRIs/MAOIs, clonus, hyperreflexia | Cyproheptadine, BZDs |
| Sepsis | Fever WITH source/cytokine response | Sepsis bundle |
Medications & dosing
| Drug | Dose | Notes |
|---|---|---|
| Cold-water immersion (preferred for exertional) | Immerse to neck if available | Fastest cooling rate; stop at 38.5 °C to avoid overshoot |
| Evaporative cooling | Mist + fan; ice packs to axillae/groin/neck | Use if immersion not available |
| Lorazepam (shivering) | 0.05–0.1 mg/kg IV (max 4 mg) | Suppress shivering during cooling |
| Dantrolene (NOT for heat stroke) | 2.5 mg/kg IV | Use only for malignant hyperthermia / NMS — NOT effective in heat stroke |
| 0.9% NaCl | 20 mL/kg IV bolus | Avoid over-resuscitation — pulmonary edema risk |
Management / next steps
- Remove from heat, undress, monitor
- Cool aggressively (target < 39 °C within 30 min) — DO NOT use antipyretics
- Stop cooling at 38.5 °C to prevent rebound hypothermia
- ICU; monitor for rhabdo, AKI, DIC, hepatic injury
Source: https://fprmed.com/fprmedcom/Pages/Pedi/Heat_related_Illness.html
← Back to Pediatric DDx