USMLE Prep - Medical Reference Library

Exertional Heat Stroke - Cold Water Immersion First

System: Wilderness Medicine • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Core temperature over 40 C with CNS dysfunction requires immediate whole body cold water immersion when feasible; cool first, then transport while managing airway and electrolytes.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

For Exertional Heat Stroke Cold Water Immersion, frame the differential by acuity and pathophysiology, then align diagnostics to the leading hypotheses. Prioritize stabilization while obtaining high‑yield studies such as CBC (Baseline hematology), BMP (Electrolytes/renal). Incorporate bedside imaging and targeted labs to define severity and identify complications; synthesize results with clinical trajectory to refine the working diagnosis and disposition needs.


Treatment Strategy & Disposition

Initiate disease‑directed therapy alongside supportive care, titrating to objective response. Pharmacologic options commonly include Analgesia/Antipyretics. Use validated frameworks (e.g., Cooling Options) to guide escalation and site of care. Address precipitating factors, de‑escalate empiric therapies with data, and arrange follow‑up for monitoring and risk‑factor modification; admit patients with instability, high risk of deterioration, or needs for close monitoring.


Epidemiology / Risk Factors

  • Risk factors vary by condition and patient profile

Investigations

TestRole / RationaleTypical FindingsNotes
CBCBaseline hematologyAbnormal counts
BMPElectrolytes/renalDerangements

Cooling Options

MethodNotes
Cold water immersionFastest and preferred when feasible
Evaporative and convective coolingAlternative when immersion unavailable
Ice packs to groin axilla neckAdjunct only

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
BenzodiazepineGABA-A potentiationMinutesControl shivering/agitation during coolingRespiratory depression
Isotonic fluidsVolume expansionHoursSupportiveFluid overload
Avoid antipyreticsN/AImmediateIneffective in heat stroke

Prognosis / Complications

  • Prognosis depends on severity, comorbidities, and timeliness of care

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

Notes

Plan return to activity only after medical clearance. Prevent with acclimatization and hydration strategies.


References

  1. WMS heat illness guideline — Link
  2. ACSM position on exertional heat illness — Link