USMLE Prep - Medical Reference Library

Heat Stroke — Rapid Cooling (Ice‑Water Immersion) and Complication Management

System: Emergency Medicine • Reviewed: Sep 1, 2025 • Step 1Step 2Step 3

Synopsis:

Hyperthermia with CNS dysfunction requires immediate whole‑body cold‑water immersion (exertional) or aggressive evaporative cooling; target core 39°C. Manage airway, fluids, rhabdomyolysis, DIC, and organ failure; avoid antipyretics.

Key Points

  • Use the highest‑yield diagnostic test early; do not let testing delay time‑critical therapy.
  • Set objective targets (hemodynamic, neurologic, respiratory) and reassess frequently.
  • Plan definitive source control or reperfusion when indicated; document follow‑up and patient education.

Algorithm

  1. Recognize heat stroke: hyperthermia with CNS dysfunction; move to cool environment; strip clothing.
  2. Start whole‑body ice‑water immersion when exertional HS; otherwise evaporative + ice packs if immersion unavailable.
  3. Secure airway/breathing/circulation; large‑volume IV fluids as needed.
  4. Monitor core temp q5 min; stop cooling at ~39°C; prevent overcooling.
  5. Screen and treat complications (rhabdomyolysis, AKI, DIC, arrhythmias); avoid antipyretics.
  6. Admit to ICU; counsel on return‑to‑activity and heat‑risk mitigation.

Clinical Synopsis & Reasoning

Hyperthermia with CNS dysfunction requires immediate whole‑body cold‑water immersion (exertional) or aggressive evaporative cooling; target core 39°C. Manage airway, fluids, rhabdomyolysis, DIC, and organ failure; avoid antipyretics.


Treatment Strategy & Disposition

Stabilize ABCs. Initiate guideline‑concordant first‑line therapy with precise dosing and continuous monitoring. Escalate to advanced/procedural interventions based on explicit failure criteria. Define ICU, step‑down, and ward disposition triggers; involve specialty teams early.


Epidemiology / Risk Factors

  • Risk varies by comorbidity and precipitants; see citations for condition‑specific data.

Investigations

TestRole / RationaleTypical FindingsNotes
Core temperature (rectal)SeverityOften >40°CSerial measurements during cooling
CK, CMP, coagsComplicationsRhabdomyolysis, AKI, DICTrend q6–8 h initially
UA/myoglobinRhabdo screenPositive in many casesHydration + alkalinization selectively

Pharmacology

Medication/InterventionMechanismOnsetRole in TherapyLimitations
Cold‑water immersion (procedure)Physical coolingImmediateFirst‑line for exertional heat strokeStop at 39°C core temp
IV crystalloidsVolume supportMinutesTreat hypovolemia/rhabdoAvoid overhydration
Benzodiazepines (shivering)GABAergicMinutesControl agitation/shiveringMonitor airway

Prognosis / Complications

  • Outcome depends on timeliness of diagnosis and definitive therapy; monitor for complications.

Patient Education / Counseling

  • Provide red‑flag education, adherence guidance, and explicit return precautions; arrange timely specialty follow‑up.

References

  1. Wilderness Medical Society Clinical Practice Guidelines for Heat Illness (2024 update) — Link
  2. DoD/CHAMP Clinical Practice Guideline: Heat Illness (June 2024) — Link