Avoiding Heat Stress and Heat Related Injuries

Mojave Desert

We had a relatively cool June, but moving into July, the temperatures have increased into the upper 90s and lower 100s. Dehydration, heat exhaustion and heat stroke become a concern--especially if exercising or working outside. Rather than distinct conditions, dehydration, heat exhaustion and heat stroke should be viewed as points along a continuum from easily preventable/treatable dehydration to heat exhaustion (not able to continue with the physical activity) to the more serious and life threatening heat stroke. Early intervention is the best remedy to stop heat stress from escalating into something more serious.

What Happens to Create Heat Exhaustion and Heat Stroke

The skin is the primary organ for cooling the body, using radiation (heat lost directly to the atmosphere), convection (heat loss by the movement of air), conduction (heat loss through contact with a cooler body or material), and evaporation (heat loss by turning water--i.e., sweat--into vapor). As the body attempts to cool itself, it produces sweat, drawing water out of the body, and potentially causing dehydration. If the body still cool, the victim will begin to suffer hyperthermia--an increase in body temperature, which can have dire effects on the body's functioning, compounded generally by dangerous levels of dehydration.

The skin's ability to cool the body can be impaired in several ways. First, in order to work effectively, there must be adequate skin exposure. That means, avoiding tight or bulky clothing that reduces exposure and increases insulation. Second, the environment must be conducive to cooling. Obviously, a hot day will put more heat stress on a body than a cool day; and a humid day will minimize the ability of the body to cool itself through evaporation. Thus, the most dangerous conditions are high heat and humidity. Third, due to morphologic and physiologic reasons, children do not adapt as effectively when exposed to heat stress, making them more susceptible to heat- related illness and dehydration syndromes. Likewise older adults, especially those with certain illnesses or disabilities, may be more susceptible.

Who Is At Risk

The following are the most at risk from heat injuries:

• Infants and young children.
• The elderly and chronically ill (often with associated heart diseases, lung diseases, kidney diseases, or who are taking medications that make them vulnerable to dehydration and heat strokes) 
• Athletes 
• Individuals who work outside and physically exert themselves under the sun
• The weekend warriors (those that are less fit and overexerting, and those that, even if fit, are not acclimated to exercising in the heat).
• Never quit/never give up individuals, because they will push themselves beyond healthy limits. 

Signs of Heat Stroke

These include:

• Confusion/disorientation – cannot remember simple things,complete simple/routine tasks. 

• Irritability/agitation – a change in temperament. 

• Belligerence – easily frustrated, compounded by the confusion and irritability. 

• Lightheadedness 

• Incoordination 

• Fatigue – in excess of what would be anticipated. 

• Paradoxical chills – goose bumps and shivering in the face of high environmental temperature (an ominous sign). 

• Hard or impossible to keep working or playing. 

• Loss of coordination, dizziness or fainting 

• Dehydration 

• Dark colored urine.

• Profuse sweating or pale skin

• Headache, nausea, vomiting or diarrhea 

• Stomach/intestinal cramps or persistent muscle cramps
• High body temperature, 

• The absence of sweating, with hot red or flushed dry skin, 

• Rapid pulse, 

• Difficulty breathing, 

• Seizure and/or coma.

Note that some individuals can develop symptoms of heat stroke suddenly and rapidly without warning.

Treating Heat Exhaustion or Heat Stroke

• Stop the activity immediately.
• Move the victim to a cool/shady area.
• Remove head covering (the head is the best suited for cooling) and excess clothing.
• Have the victim lie on his/her back with legs elevated above heart level.
• Cool the victim until body temperature is at least down to 101 degrees Fahrenheit (38.3 degrees Celsius). This can by done by applying cool or tepid water to the skin (for example, spraying the person with cool water from a hose or having the person take a cool shower), fan the victim to promote sweating and evaporation, and place ice packs under the armpits and groin, or on the back of the neck.
• Get some fluids (it is not enough to just stay hydrated, but you also need to maintain electrolyte levels to prevent neurological problems). It is important to replace salt lost to sweating.
• Seek medical assistance.

Prevention

Prevention takes some common sense and planning.

1.    Stay cool:

• Work or exercise in early morning or late evening. Avoid the hottest times of the day.
• Avoid working or exercising when its hot and humid.
• Reduce the intensity and duration of your work or exercise--take breaks.
• Get into good physical shape, and try to acclimate to hotter weather. 
• Take frequent rests and and remove hats, headgear, and excess clothing.
• Wear hats and light-colored, lightweight, loose clothes.
• If you have a bandanna or similar wrap, and/or a cotton shirt, it may help to soak it in water to maximize evaporation
• Use a sun-screen to prevent sunburn. Sunburned skin is less effective at cooling the body.

2.   Stay hydrated:

• Drink often and drink regularly. Do not rely on thirst, by the time you are feeling thirsty, there is already a significant fluid deficit. Most individuals don't drink enough to replace fluids, so if you don't start drinking until you feel thirsty, you are already behind in the game. It only takes a loss of fluid equal to 2% of your body mass to impair performance. 
• Drink more than just water. When you exert yourself, you lose electrolytes as well as fluid. Replacing the fluid alone (with just water) can lead to electrolyte imbalances. These imbalances can be life-threatening.
• Monitor your urine, it should be the color of lemonade, not apple juice.
• Avoid consuming drinks containing alcohol or caffeine.

3.  Stay healthy:

• Eat and sleep well. Maintain a well-balanced diet. Replenish salt and rehydrate. Avoid alcohol, soda, caffeine and other stimulants.
• Gain or lose weight slowly, allowing your body time to acclimate to the change.
• Sharp drops in weight after exertion can be an indicator of excessive fluid loss.
• Know the warning signs of heat related illness and dehydration syndromes.
• Eat fruits and vegetables with high water content.

Sources:

1. National Center for Sports Safety
2. National Athletic Trainers' Association
3. American Osteopathic Association
4. MedicineNet.com
5. Wikihow