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Heat stroke
From WikEM
Contents
Background
- Severe end of heat-related illness spectrum
- True emergency - universally fatal if left untreated
- Mortality approaches 30% even with treatment[1]
- Hallmark is multisystem organ dysfunction from heat-induced damage resulting in systemic inflammatory response
Types
- Classic (nonexertional) - insidious development over days
- Seen in children and elderly
- Exertional - rapid onset during exercise or other exertion
- Seen in otherwise young, healthy individuals
Clinical Features
- Symptoms[2]
- Anhidrosis is frequently present; however, its absence does NOT rule out heat stroke
- May have massive hematochezia secondary to dec perfusion and intestinal ischemia[3]
Differential Diagnosis
Environmental heat diagnoses
Non-Environmental
- Infectious
- Endocrine
- Neurologic
- Hypothalamic bleeding or infarct
- CVA
- Status epilepticus
- Toxicologic
- Anticholinergic toxidrome
- Sympathomimetic toxicity
- Salicylate toxicity
- Serotonin syndrome
- Malignant hyperthermia
- Neuroleptic malignant syndrome
- Withdrawal (e.g. ETOH, Benzodiazepines)
Altered mental status and fever
- Infectious
- Sepsis
- Meningitis
- Encephalitis
- Cerebral malaria
- Other
Evaluation
Workup
- Core temperature (continuous monitoring is ideal, e.g. with bladder temperature monitor)
- Blood glucose
- ECG
- CBC
- Metabolic panel
- LFTs
- Blood gas
- Lactate
- Coagulation studies (DIC)
- Creatine phosphokinase and myoglobin (Rhabdomyolisis)
- Urinalysis
- Chest x-ray
- CT brain (± LP), if indicated (Cerebral Edema)
Evaluation
- Clinical diagnosis
Management
- Address ABCs
- Rapid cooling (see below) - mainstay of treatment
- Reduces morbidity/mortality, should be started in prehospital setting if no other life-threats exist[2]
- Remove from environment
- IVF (for renal protection and avoiding rhabdomyolysis)
- Bolus if hypotensive
- Infusion titrated to UOP (goal 2-3ml/kg/hr)
Rapid Cooling
- Cooling end point should be ~39°C (102.2°F) - no good data for this goal[1]
- No role for: antipyretics or dantrolene
- Combination of methods, or adjuncts such as cool IVF may increase efficacy of individual methods
Techniques
- Cool water immersion - treatment of choice[2][4]
- Immersion of body to level of torso or neck in cool or ice-water
- Best for exertional heat stroke in young/healthy patients, but benefit shown in elderly patients as well
- Diffuse application of ice or cold packs to entire body may provide similar benefit (but less data)
- Applying ice packs only to neck, axillae, groin provides only minimal cooling[1]
- Benefits: most rapid decrease in temperature, some studies have shown 100% survival (esp when started within 30 minutes of collapse)[1][2][4]
- Disadvantages: requires special equipment (may not be immediately available), poorly tolerated, unable to provide defibrillation or many other resuscitative measures
- Evaporative/Convective Cooling
- Spray cool water (15°C / 59°F) on patient while directing fans at patient
- Benefits: Easier to apply in ED and while performing other interventions
- Disadvantages: Slower cooling (than immersion) with slightly higher morbidity/mortality
- Invasive
- Techniques such as cardiopulmonary bypass/ECMO or cold water lavage of body cavities has been reported, but inadequate data to recommend[1]
Complications
- Hypotension
- Usually responds to small fluid bolus (500cc) and body cooling
- If no response to fluids → consider vasopressors (dopamine or dobutamine)
- Avoid peripheral vasoconstriction (e.g. norepinephrine), which may redirect blood flow away from skin and diminish cooling
- Electrolyte abnormalities
- Variable: hypokalemia and hyper or hyponatremia may be seen
- Hematologic - DIC or abnormal bleeding
- Hepatic injury - almost always reversible
- Renal failure
- ARDS
- Seizure - treat with Benzodiazepines
- Neurologic deficit
- Persistent in 20%, associated with high mortality
Disposition
- All patients require admission
See Also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Gaudio FG, Grissom CK. Cooling Methods in Heat Stroke. J Emerg Med. 2015 Oct 31.
- ↑ 2.0 2.1 2.2 2.3 Becker JA, Stewart LK. Heat-related illness. Am Fam Physician. 2011 Jun 1;83(11):1325-30.
- ↑ Lambert GP. Intestinal barrier dysfunction, endotoxemia, and gastrointestinal symptoms: the 'canary in the coal mine' during exercise-heat stress? Med Sport Sci. 2008;53:61-73.
- ↑ 4.0 4.1 Pryor RR, Roth RN, Suyama J, Hostler D. Exertional heat illness: emerging concepts and advances in prehospital care. Prehosp Disaster Med. 2015 Jun;30(3):297-305.
