Heatstroke

Heatstroke is a life-threatening condition in which the patient's thermoregulatory mechanisms are unable to adequately respond to heat stress. This results in an increase in body temperature leading to organ dysfunction and failure. Temperatures are usually very high, often in excess of 41 ° C (106° F). In classic heatstroke, precipitants include exposure to high ambient temperature in a patient with a preexisting disease (coronary artery disease, diabetes, alcohol, and obesity) or medication (phenothiazines, anticholinergics, sedatives, diuretics) that limits thermoregulation. This may occur, for example, in older patients who are confined to a hot environment. Care must be taken to rule out infectious causes of fever in these patients.

In exertional heatstroke, precipitants include physical exertion, high temperature, humidity approaching 100% (evaporation ceases), and incomplete acclimatization. Heatstroke patients are hot, usually, though not always, anhydrotic, and have CNS abnormalities. Rapid and aggressive cooling measure are imperative in all heatstroke patients.

Heat exhaustion is a less emergent form of heat illness that is treated primarily by cooling and oral or IV fluid replacement. Heat cramps may also occur and seem to be related to salt depletion. Treatment consists of oral or IV fluid and NaCI repletion.

Causes

Heat exhaustion is typically caused when people who are not well adjusted to heat exercise in a hot, humid environment. The most common causes of heat emergencies are Dehydration, Prolonged or excessive exercise, Medications, such as diuretics, neuroleptics, phenothiazines, and anticholinergics, Cardiovascular disease, High temperatures or humidity, Cardiovascular disease, Sweat gland dysfunction and Alcohol use. When it is very humid, this mechanism does not work properly. The body loses a combination of fluids and salts.

Symptoms

• Fever +++++
• Altered mental status (agitation, confusion) +++++
• Headache
• Dizziness
• Weakness
• Anorexia
• Stupor
• "Sense of impending doom"

Signs

• Hyperthermia +++++
• Altered mental status (coma, stupor, agitation) +++++
• Hot, dry skin (not universal) ++++
• Neurologic deficits in severe cases
• Oliguria (may be sign of rhabdomyolysis in exertional heat stroke)
• Hypotension
• ECG changes
• Disseminated intravascular coagulation (DIC)

Treatment

Treatment of heat stroke

• Get professional medical help as quickly as possible.
• Move to a cool area as quickly as possible.
• Treatment is aimed at reducing your core temperature to normal as quickly.
  
• The doctor may use immersion, evaporative, or invasive cooling techniques.
• Increase ventilation by opening windows or using a fan.
• Shower the skin with cool, but not cold.
• Cover the body with cool, damp towels or sheets, or immerse in cool water,
• Gently massage the skin to encourage circulation.
• Your urine output will be monitored.

Once in hospital, the patient may be given oxygen through a mask, intravenous fluids through a drip and medication to regulate their temperature.