Dr. Francis SANWO

 

Heat stroke versus Heat exhaustion.   Heatstroke and heat exhaustion are illnesses caused by exposure to extreme heat. If left untreated, heat exhaustion can progress into heatstroke, which may be life-threatening.                                              

Heat stroke, also known as sun stroke, is a type of severe heat illness that results in a body temperature greater than 40.0 °C (104.0 °F) and confusion. It is the most serious heat-related illness and it is a life-threatening medical emergency. Onset can be sudden or gradual.        

There are two types of heatstroke: exertional and non-exertional.

Non-exertional heatstroke occurs in those who cannot adapt well to increasingly hot temperatures. Older adults, people with chronic illnesses, and infants are often affected. A person typically experiences this type of heatstroke when they are indoors without air conditioning, and they may not be engaging in any physical activity. It can take several days of high temperatures for non-exertional heatstroke to occur, and it is common during extreme heat waves.

Exertional heatstroke occurs in people whose bodies can no longer adapt to rising temperatures while exercising or working. This condition can develop within a few hours, and it usually affects people who are spending time outdoors.  Exertional heat stroke (EHS) can happen in young people without health problems or medications – most often in athletes, outdoor laborers, or military personnel engaged in strenuous hot-weather activity .

Spending time in closed cars puts small children and pets at high risk of heatstroke. The CDC estimate that when the temperature outdoors is 80ºF, the temperature inside a closed car rises to 109ºF within 20 minutes. The hotter it is outside, the faster the temperature rises inside a vehicle. If not treated immediately, heatstroke can damage multiple organs and systems, including the: brain and nervous system (e.g. seizures), circulatory system, lungs, liver, kidneys (kidney failure), digestive tract and muscles (rhabdomyolysis).     

 Heatstroke is a type of hyperthermia. It is distinct from a fever, where there is a physiological increase in the temperature set point. Heat stroke occurs when thermoregulation is overwhelmed by a combination of excessive metabolic production of heat (exertion), excessive environmental heat, and insufficient or impaired heat loss, resulting in an abnormally high body temperature.                                                                                                                                         Heat exhaustion is less serious than heatstroke. Anyone who suspects that they have heat exhaustion should immediately rest and rehydrate. If symptoms do not improve, seek medical attention to prevent heatstroke. Heat exhaustion can lead to: muscle cramping, a rapid, weak pulse, a general sense of weakness, nausea or vomiting, excessive sweating and cold, clammy skin. Others are dizziness and sometimes fainting, dark-colored urine and headaches.

Heatstroke on the other hand may begin with symptoms of heat exhaustion. It can be life-threatening, and symptoms may rapidly worsen, to include: a temperature of 104ºF or higher, hot, dry skin, a racing heartbeat, confusion, agitation, slurred speech, seizures, disorientation, a lack of sweating and coma. If a heat stroke occurs when the person is asleep, symptoms may be harder to notice. However, in exertional heat stroke, the affected person may sweat excessively.  Organ failure  and death             may eventually result.                                                                          Risk factors

Certain factors can make a person more likely to experience heat exhaustion or heatstroke. These include: being overweight or obese, having a significant disability, having a sunburn, using some prescription medications for heart conditions or high blood pressure, particularly diuretics, beta blockers and experiencing sudden changes in temperature, such as by traveling from a cold to a hot climate. Spending time outdoors in extreme heat, or indoors without a way to cool down is also a risk factor. Others include heat waves, high humidity,  alcohol, stimulants, heart disease, and skin disorders.  These inhibit cooling and cause dehydration.                     

Treatment.                                   

Treatment of heat stroke involves rapid mechanical cooling along with standard resuscitation measures.

The body temperature must be lowered quickly. The person should be moved to a cool area (indoors, or at least in the shade) moving to a shady location, resting out of the sun and clothing removed to promote heat loss (passive cooling). Active cooling methods should also be used, if possible: The person is bathed in cold water, or a hyperthermia vest can be applied. Cold compresses to the torso, head, neck, and groin will help cool the victim, running cool water over the skin or applying cool, wet towels to the body. A fan or dehumidifying air-conditioning unit may be used to aid in evaporation of the water (evaporative method).

Immersing a person into a tub of cold water (immersion method) is a widely recognized method of cooling. This method may require the effort of several people and the person should be monitored carefully during the treatment process. Immersion should be avoided for an unconscious person, but if there is no alternative, the person's head must be held above water.

Thus, aggressive ice-water immersion remains the gold standard for life-threatening heat stroke.

Hydration is important in cooling the person. In mild cases of concomitant dehydration, this can be achieved by drinking water, or commercial isotonic sports drinks may be used as a substitute. In exercise- or heat-induced dehydration, electrolyte imbalance can result, and can be worsened by excess consumption of water. Hyponatremia can be corrected by intake of hypertonic fluids. Absorption is rapid and complete in most people but if the person is confused, unconscious, or unable to tolerate oral fluid, then an intravenous drip may be necessary for rehydration and electrolyte replacement. 

Prevention 

The risk of heat stroke can be reduced by observing precautions to avoid overheating and dehydration. Light, loose-fitting clothes will allow perspiration to evaporate and cool the body. Wide-brimmed hats in light colors help prevent the sun from warming the head and neck. Vents on a hat will help cool the head, as will sweatbands wetted with cool water. Strenuous exercise should be avoided during hot weather, especially in the sun peak hours as well as avoiding confined spaces (such as automobiles) without air-conditioning or adequate ventilation.

In hot weather, people need to drink plenty of cool liquids and mineral salts to replace fluids lost from sweating. Thirst is not a reliable sign that a person needs fluids. A better indicator is the color of urine. A dark yellow color may indicate dehydration.

The following strategies can also  help: staying indoors during the hottest part of the day, trying to stay in the shade when outdoors, drinking an extra 2–4 cups of water every hour while exposed to high temperatures, taking frequent breaks when working or exercising outdoors on hot days, wearing loose, light-colored clothing, using cooler water for showers and baths, wearing a wide-brimmed hat to shield the face from the sun and avoiding drinks that dehydrate, including those with caffeine or alcohol. Others are wearing breathable fabrics like cotton, rather than synthetic blends and spending part of the day in an air-conditioned place, such as a mall, library, or movie theater.

No one should remain alone in a parked car in extremely hot weather. Doing so could be especially dangerous for children and people aged 65 and older.

Summary.

With appropriate, timely treatment, a person can fully recover from heat-related illnesses.

Recognizing symptoms of heat exhaustion and taking steps to cool down can prevent the condition from developing into heatstroke.

If left untreated, heatstroke can result in serious complications or death. When a person receives the right treatment early enough, they can fully recover from heatstroke.

Even on the hottest days, these illnesses can usually be prevented by planning and taking precautions.

Spending time in the shade will help to prevent heat exhaustion.