Harbingers of summer, the first rays of sun are tempting us to go outside. Temperatures are still moderate but with a rising thermometer, one should once more keep the dangers in mind that result from heat exposure over a long time: thermic emergencies are often underestimated. However, they can be lethal. Burns and electric shocks also damage tissue through heat. Learn more about these three types of thermic injury and how to act in case of an emergency.

sun in the sky

Image: “Touch the Sky” by Elescir. License: CC BY 2.0

Heat Emergency

Heat can cause a number of emergencies: from circulatory problems, heat cramps and heat exhaustion right up to sunstroke or heatstroke. In case of high temperatures, the body is not capable of giving of heat to the outside anymore and thus cannot protect itself from overheating. Increased sweating causes a loss of liquid and electrolytes. Physical exercise additionally worsens the situation.

Heat syncope/Heat exhaustion

If in standing position for a long time, heat can cause orthostatic dysregulation with short unconsciousness (heat syncope) or blackouts (heat exhaustion). This is caused by vasodilation due to heat, blood flows into the periphery, which results in a temporary insufficient supply of the brain. Shock symptoms are clinically visible (tachycardia, hypotension, cold sweat), the skin temperature is not elevated. Treatment of heat syncope/heat exhaustion occurs through (intravenous) administration of fluid, shock positioning and cooling. Especially older patients should be hospitalized for clarifying possible differential diagnoses.

Heat exhaustion

Heat exhaustion caused by long and heavy sweating is also a mild form of heat emergency. Too little fluid can cause dehydration with headache, physical exhaustion and drowsiness. A disturbed electrolyte balance (loss of sodium) promotes muscle cramps. Therapy is done corresponding to the interventions in case of heat syncope. However, a stationary clarification is usually not necessary.

Heatstroke and sunstroke

Severe heat emergencies are heatstroke and sunstroke. Heatstroke occurs if the heat production and heat supply exceed the heat emission of the body e.g. when exercising in the heat or in case of young children and elderly people. Heatstroke causes hyperthermia with dry, warm skin, drowsiness, nausea and vomiting, tachycardia, hypotension and cerebral seizures as well as organ failure. Heatstroke always has to be treated in a hospital since it can be lethal. Besides cooling, shock positioning and fluid replacement, intubation and anticonvulsive therapy might be necessary.

Sunstroke can be dangerous as well. It results from overheating of the brain, usually due to intensive sun exposure. Besides symptoms of meningeal irritation, cerebral edemas are also possible. Patients suffering from sunstroke show similar symptoms as patients suffering from heatstroke: hyperthermia of the head, drowsiness, vomiting and additionally symptoms of meningeal irritation up to cerebral seizures. If these severe symptoms are present, a hospitalization and further treatment are indicated additionally to above-mentioned interventions.


Burns are tissue injuries caused by local heat exposure and heating of the respective tissue to at least 45° e.g. through fire, hot liquids (scalds) but also through lightning or electric shocks.

The danger of burns for the organism lies within the destruction of the vessel barrier (endothelial cells and endothelial surface layer) and the resulting movement of fluid into the interstitial space. This leads to hypovolemia resulting in hypovolemic shock. Furthermore, intravascular activation of blood coagulation (disseminated intravascular coagulation) can occur as possible complication and may cause multiple organ failure by damaging organs. All complications together are called burn disease and can be associated with additional inhalation injury and smoke intoxication depending on the cause of the burn.

Characterizing burns

Generally, burns can be differentiated by their extent and degree. The degrees of burn describe the depth of burn wounds (see table).

 Degree of burn Characteristics Symptoms Healing
1st degree limited to the epidermis, no destruction of skin, hyperemia, edema from itching to pain flawless spontaneous recovery
 2nd degree (a+b)  a: superficial, limited to the epidermis, hyperemia, blistering, wet wound bed, intact sensibility
b: deep, epidermis and dermis are damaged, blistering, dry wound bed, bright and reddened areas
severe pain a: usually unscarred spontaneous recovery
b: partial recovery with scar formation
 3rd degree damage of all skin layers including the superficial fascia, greyish whitish discoloration of the skin  painless since the nerve endings have been destroyed skin regeneration no longer possible
  4th degree involves muscles, tendons or bones, charring of tissue  painless skin regeneration no longer possible

The extent of a burn describes the affected body surface, which can be estimated easily using certain rules. The size of the palm of an adult equals about 1 % of the body surface area (BSA). The Wallace rule of nine is used to divide the body surface area into regions, each equaling 9 % of the total BSA: Head incl. neck and one arm equal 9 %, one leg 2 times 9 % (front side = 9 %, back side = 9 %) and the trunk equals 4 times 9 % (front side of the thorax = 9 %, back side of the thorax = 9 %, front side of the abdomen = 9 %, lumbar region = 9 %). The genital region equals 1 % of the BSA. For children, this classification is shifted due to different proportions.

The combination of burnt body surface area and degree of burn give the severity level of the burn. We always speak of severe burns if

  • head, hands or feet and the genital region are affected or
  • 25 % of the BSA show 2nd degree burns (20 % for children and adults) or
  • 10 % of the BSA show 3rd degree burns.

Severe burns should always be treated in a burn unit.

Therapy of burns

Besides maintaining self-protection, first measures in case of burns should be securing of vital functions (if necessary through intubation), removing of clothing and sterile covering of the wound. Ventilation with 100 % oxygen as well as on time volume replacement and analgesia are medically sensible. Further treatments can be carried out in a brand unit or a normal hospital depending on the severity of the burn. (see above)

There are two reasons calling for a careful handling when cooling burn patients. Firstly, cooling leads to a so-called afterburn, an injury of the surrounding tissue, which can spread to deeper skin layers. Secondly, the patient can easily slip into hypothermia due to a lack of protection of the burnt skin areas and cooling for too long.

Electric Shock

In case of electrical accidents, a mix of symptoms of thermic (local burns) and electrical injuries (cardiac arrhythmia) can be seen. The severity of the injury depends on the voltage (low voltage <1000V = domestic electricity, high voltage > 1000V, lightning), current strength, duration of exposure, contact area and other general factors such as moisture and conductivity of the skin. Possible consequences are:

  • Burns
  • Cardiac arrhythmia (ventricular fibrillation) and cardiac arrest
  • Muscle injuries leading to muscle contractions
  • CNS-injuries with disturbances of consciousness

Additionally, secondary injuries due to falls (e.g. fractures, internal injuries) often occur. Current brands are injuries of the skin caused by entry and exit of current. In case of lightning strikes, a so-called lightning figure in form of a fern-like branching can often be seen on the skin.


Self-protection is of top priority when treating patients in cases of electric accidents. Before the patient can be rescued from the danger zone, the electric circuit has to be broken off. In cases of high voltage accidents, this has to be done by qualified personal. The following measures are similar to those against burns. Additionally, possible cardiac arrhythmias have to be treated (CPR) and potential other injuries (e.g. fractures) have to be attended appropriately (bone setting, splint)

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