Need for intensive cooling resources not available
Exertional heat stroke with immersion need
Multi-organ dysfunction
ICU level care need
Treatment
Cooling and environment
Cooling strategy
Immediate environment changes
Shade or cooled space
Remove excess clothing and equipment
Evaporative cooling
Tepid water mist
Fan directed airflow
Wet towels with airflow
Re-wet frequently
Ice pack placement
Axillae
Skin protection barrier
Groin
Skin protection barrier
Neck
Skin protection barrier
Cooling targets
Symptom improvement
Reduced dizziness
Temperature <38 C if elevated
Avoid overshoot hypothermia
Fluids and electrolytes
Oral rehydration preferred when safe
Oral rehydration solution
Sodium containing fluids for heavy sweating
Small frequent sips
Nausea mitigation
Avoid water-only overcorrection in prolonged exertion
Hyponatremia risk
IV isotonic fluid resuscitation when needed
0.9% saline IV bolus 10-20 mL/kg
Reassess symptoms and vitals after each bolus
Orthostasis improvement
Additional bolus 10 mL/kg if ongoing hypovolemia
Lung exam monitoring for overload
Balanced crystalloid alternative per local practice
Hyperchloremia mitigation rationale
Electrolyte correction principles
Hyponatremia evaluation before hypertonic therapy
If seizure or severe neurologic symptoms, treat per hyponatremia emergency pathway
Hypokalemia correction when present
Oral potassium preferred if mild and tolerating PO
Recheck potassium after replacement
IV potassium if severe or unable to tolerate PO
Cardiac monitoring for IV replacement
Nausea and vomiting control
Ondansetron ODT 4 mg
Repeat 4 mg after 8 hours as needed
QT prolongation risk review
Ondansetron IV 4 mg
Repeat 4 mg after 6-8 hours as needed
QT prolongation risk review
Exertional cramps and pain
Heat cramps management
Oral electrolyte solution
Sodium replacement emphasis
Gentle stretching of affected muscle
Stop exertion until resolved
Magnesium only when deficiency suspected
Routine magnesium not consistently beneficial
Analgesia options
Acetaminophen 650 mg PO
Fever treatment not primary mechanism
NSAID caution
AKI risk in dehydration
Complications and escalation
Rhabdomyolysis management when suspected
Isotonic fluids titrated to urine output
Urine output >=1 mL/kg/hour target in significant rhabdomyolysis
Pulmonary edema monitoring in at-risk patients
Hyperkalemia management pathway if present
ECG monitoring
Calcium therapy if ECG changes
If heat stroke cannot be excluded, immediate heat stroke protocol
Rapid active cooling to target 38-39 C
Ice water immersion preferred for exertional heat stroke when feasible
ICU consult
Multi-organ dysfunction monitoring
Evidence notes for heat illness management
Rapid cooling is primary determinant of outcome in heat stroke
Class I recommendation based on consensus in emergency and wilderness medicine
Oral rehydration effective for mild heat illness with intact mental status
ACEP Level C style recommendation based on consensus and small studies
Special Populations
Pregnancy
Pregnancy considerations
Maternal hyperthermia risks
Fetal distress concern with sustained high temperature
Hydration strategy
Lower threshold for IV fluids if vomiting
Avoid hypotonic fluids in hyponatremia risk
Fetal assessment triggers
If viable gestation and significant symptoms, obstetric consult
If abdominal pain or vaginal bleeding, urgent obstetric evaluation
Geriatric
Older adult considerations
Impaired thermoregulation
Reduced sweating
Medication drivers
Diuretics and anticholinergics
Volume assessment pitfalls
Blunted tachycardia response
Fluid resuscitation caution
Heart failure risk
Lung exam and oxygenation monitoring
Pediatrics
Pediatric considerations
Higher surface area to mass ratio
Faster heat gain
Weight-based fluids
0.9% saline 10-20 mL/kg bolus
Reassess perfusion and mental status
Return to play guidance
Same-day return avoidance after heat exhaustion episode
Graduated acclimatization plan
Background
Epidemiology
Epidemiology snapshot
Heat exhaustion common in hot weather and exertional settings
Peak incidence during heat waves
Risk concentration
Athletes early in season
Outdoor workers
Older adults and chronic disease patients
Recurrence risk
Prior heat illness increases future risk
Pathophysiology
Heat exhaustion mechanisms
Heat production exceeds heat dissipation
High ambient temperature
High humidity reduces evaporative cooling
Dehydration and salt loss
Reduced plasma volume
Reduced cardiac output reserve
Splanchnic vasoconstriction and gut ischemia contribution
Nausea and vomiting
Progression pathway
Persistent heat stress leading to heat stroke if untreated
Therapeutic Considerations
Cooling rationale
Lower core temperature reduces physiologic strain
Improved cardiovascular stability
Evaporative cooling effectiveness
Works best with airflow and low humidity
Fluid therapy rationale
Isotonic fluids restore intravascular volume
Improved orthostatic tolerance
Sodium replacement when heavy sweating
Prevent exercise-associated hyponatremia
Return to exertion rationale
Heat acclimatization takes 7-14 days
Graded exposure reduces recurrence risk
Patient Discharge Instructions
copy discharge instructions
Heat exhaustion discharge instructions
Rest in a cool place for 24 hours
Avoid strenuous activity for at least 24 hours
Hydration plan
Drink fluids regularly
Use electrolyte drinks if sweating heavily
Heat avoidance plan
Avoid midday heat
Wear light breathable clothing
Gradual return to activity
Resume exercise slowly over several days
Stop activity if symptoms recur
Return to ED immediately for red flags
Confusion
Fainting
Seizure
Worsening headache
Persistent vomiting
Chest pain
Trouble breathing
Not peeing for 8 hours
Dark tea-colored urine
Fever or very high temperature
Follow-up plan
Primary care follow-up within 24-72 hours if symptoms not fully resolved
Same-day follow-up if abnormal labs were present
References
Guidelines and evidence sources
Heat illness references
Wilderness Medical Society clinical practice guidelines for prevention and treatment of heat illness
Cooling and rehydration recommendations
CDC heat illness clinical guidance materials
Heat exhaustion vs heat stroke differentiation
American College of Sports Medicine position statements on exertional heat illness
Return to play and acclimatization guidance
Emergency medicine and critical care references
ACEP clinical policy style principles for hyperthermia and related emergencies
Consensus level recommendations for cooling and supportive care
Review literature on exertional heat stroke cooling modalities
Ice water immersion superiority for rapid cooling in exertional heat stroke
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.