Heat stroke in adults

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Key diagnostic factors

common

history of exposure to severe environmental heat or strenuous physical exercise

A patient with heat stroke has a history consistent with exposure to:[1]

Passive severe environmental heat (classic heat stroke), particularly in at-risk patients (e.g., older people) during a heat wave, or
Strenuous physical exercise (exertional heat stroke), particularly in younger adults, athletes, and people who exert themselves in the heat (e.g., firefighters, soldiers, construction workers).

central nervous system dysfunction

Patients with heat stroke present with central nervous system (CNS) dysfunction, particularly an altered level of consciousness, which may range from confusion to coma (encephalopathy).

Other CNS findings include:

Agitation
Lethargy
Seizures
Ataxia
Irritability.

Practical tip

The presence of CNS dysfunction (together with hot, dry skin) helps to distinguish heat stroke from heat exhaustion (though it is important to be aware that heat stroke can also present with hot, wet skin, especially exertional heat stroke, where heavy sweating is common).[2][10] In patients with heat exhaustion, mental status remains intact (and profusely sweating, cold, clammy skin is seen).[2]

hyperthermia (>40°C)

Measure rectal temperature in all patients with suspected heat stroke.[1][2] In practice, consider using an oesophageal probe in intubated patients.

An elevated core body temperature (>40°C) is consistent with heat stroke in the context of exposure to severe environmental heat or strenuous physical exercise.

Practical tip

Be aware that patients who present with a normal temperature can have heat stroke, either because of inaccurate measuring techniques or from effects of prior cooling (e.g., in the community). Continue to monitor the patient's temperature while cooling. See the Management section.

hot skin (dry or wet)

Hot skin, that is dry or wet (i.e., sweating may be absent or present), is consistent with heat stroke.[2][10]

Profuse sweating and wet skin are typically seen in exertional heat stroke, whereas the skin is commonly dry in classic heat stroke (as the sweat gland response and output is classically decreased in older adults under heat stress).[10] Additionally, the skin may be flushed (due to excessive peripheral vasodilation) or pale (a sign of vascular collapse).[10]

Practical tip

The presence of hot, dry skin (together with CNS dysfunction) can help to distinguish heat stroke from heat exhaustion (though it is important to be aware that heat stroke can also present with hot wet skin, especially exertional heat stroke, where heavy sweating is common).[2][10]

In patients with heat exhaustion, profusely sweating, cold, clammy skin is seen (and mental status remains intact).[2]

risk factors

Consider important risk factors for heat stroke:

Age <15 or >65 years old (children are not covered in this topic)[2][7]
Poor physical condition[2]
Pre-existing dehydration[2]
Obesity[2]
Lack of acclimatisation to hot environments[2][7]
Environmental factors (e.g., absence of adequate breaks, absence of shelter or shade, high humidity, high temperatures, lack of access to water).[2]

Other risk factors include:[1][2][10]

Medical conditions (e.g., diabetes, cardiovascular disease, anhidrosis, skin abnormalities [e.g., deep burns, psoriasis, extensive scarring of the skin], recent or acute illness, recent heat injury)
Congenital disorders (e.g., ectodermal dysplasia, idiopathic anhidrosis)
Drug (e.g., amphetamines) and alcohol misuse
Certain medications (e.g., diuretics, beta blockers, anticholinergics, antidepressants, antihistamines, antipsychotics).

Other diagnostic factors

common

intense thirst (heat stroke or heat exhaustion)

Present in dehydrated patients.

Note that dehydration is not a universal finding in patients with heat stroke, especially in those with classic heat stroke.[11]