Heat stroke is the most serious form of heat injury and is considered a medical emergency. If you suspect that someone has heat stroke — also known as sunstroke — call 911 immediately and give first aid until paramedics arrive.Heat stroke can kill or cause damage to the brain and other internal organs. Although heat stroke mainly affects people over age 50, it also takes a toll on healthy young athletes.
Heat stroke often occurs as a progression from milder heat-related illnesses such as heat cramps, heat syncope (fainting), and heat exhaustion. But it can strike even if you have no previous signs of heat injury.
Heat stroke results from prolonged exposure to high temperatures — usually in combination with dehydration — which leads to failure of the body’s temperature control system. The medical definition of heat stroke is a core body temperature greater than 105 degrees Fahrenheit, with complications involving the central nervous system that occur after exposure to high temperatures. Other common symptoms include nausea, seizures, confusion, disorientation, and sometimes loss of consciousness or coma.
Symptoms of Heat Stroke
The hallmark symptom of heat stroke is a core body temperature above 105 degrees Fahrenheit. But fainting may be the first sign.
Other symptoms may include:
Dizziness and light-headedness
Lack of sweating despite the heat
Red, hot, and dry skin
Muscle weakness or cramps
Nausea and vomiting
Rapid heartbeat, which may be either strong or weak
Rapid, shallow breathing
Behavioral changes such as confusion, disorientation, or staggering
If you suspect that someone has a heat stroke, immediately call 911 or transport the person to a hospital. Any delay seeking medical help can be fatal.
While waiting for the paramedics to arrive, initiate first aid. Move the person to an air-conditioned environment — or at least a cool, shady area — and remove any unnecessary clothing.
If possible, take the person’s core body temperature and initiate first aid to cool it to 101 to 102 degrees Fahrenheit. (If no thermometers are available, don’t hesitate to initiate first aid.)
Fan air over the patient while wetting his or her skin with water from a sponge or garden hose.
Apply ice packs to the patient’s armpits, groin, neck, and back. Because these areas are rich with blood vessels close to the skin, cooling them may reduce body temperature.
Immerse the patient in a shower or tub of cool water, or an ice bath.
If emergency response is delayed, call the hospital emergency room for additional instructions.
Risk Factors for Heat Stroke
Heat stroke is most likely to affect older people who live in apartments or homes lacking air conditioning or good airflow. Other high-risk groups include people of any age who don’t drink enough water, have chronic diseases, or who drink excessive amounts of alcohol.
Heat stroke is strongly related to the heat index, which is a measurement of how hot you feel when the effects of relative humidity and air temperature are combined. A relative humidity of 60% or more hampers sweat evaporation, which hinders your body’s ability to cool itself.
The risk of heat-related illness dramatically increases when the heat index climbs to 90 degrees or more. So it’s important — especially during heat waves — to pay attention to the reported heat index, and also to remember that exposure to full sunshine can increase the reported heat index by 15 degrees.
If you live in an urban area, you may be especially prone to develop heat stroke during a prolonged heat wave, particularly if there are stagnant atmospheric conditions and poor air quality. In what is known as the “heat island effect,” asphalt and concrete store heat during the day and only gradually release it at night, resulting in higher nighttime temperatures.