Heat Wave Safety |

Summer is here and the Midwest and East is experiencing record high temperatures in a major heat wave. Officials predicted a high-risk situation as the heat index surpasses heat indexes in 90s and 100s, and in some case, the 110s. Close to 200 million people might be affected in 32 states, according to the U.S. weather service.

The “heat index”, by the way, is a measure of the effects of air temperature combined with high humidity. Above 60% relative humidity, loss of heat by perspiration is impaired exposure to full sun increases the reported heat index by as much as 10-15 degrees F. All this increases the chances of heat-related illness.

We can expect the power grid to be challenged by tens of millions of air conditioning units set on “high”, and we can expect to see some major health issues if the electricity goes out and people have to fight the heat with hand fans, like they did in the “good old days”.

You might not consider a heat wave to be a natural disaster, but it most certainly is. Heat waves can cause mass casualties, as it did in Europe when tens of thousands died of exposure (not in the Middle Ages, but in 2003). They’ve already experienced one bad one this year and are predicted to have another in the near future. India, Pakistan, and other underdeveloped tropical countries experience thousands of heat-related deaths yearly.

So how exactly does heat kill a person? Your body core regulates its temperature for optimal organ function. When core body temperature rises excessively (known as “hyperthermia”), toxins leak, inflammation occurs, and cells die. Fatalities can occur very quickly without intervention, even in those who are physically fit. Even in modern times, hyperthermia carries a 10% death rate, mostly in the elderly and infirm.

The ill effects due to overheating are called “heat exhaustion” if mild to moderate; if severe, these effects are referred to as “heat stroke”. Heat exhaustion usually does not result in permanent damage, but heat stroke does; indeed, it can permanently disable or even kill its victim. It’s a medical emergency that must be diagnosed and treated promptly.

Simply having muscle cramps or a fainting spell doesn’t necessarily signify a major heat-related medical event. You will see “heat cramps” often in children that have been running around on a hot day. Getting them out of the sun, massaging the affected muscles, and providing hydration will usually resolve the problem.

In addition to muscle cramps and fainting, heat exhaustion is characterized by:

Confusion
Rapid pulse
Flushing
Nausea and Vomiting
Headache
Temperature elevation up to 105 degrees F

If no action is taken to cool the victim, they could easily go on to heat stroke. In addition to all the possible signs and symptoms of heat exhaustion, heat stroke will manifest as loss of consciousness, seizures or even bleeding (seen in the urine or vomit). Breathing becomes rapid and shallow.

If not dealt with quickly, shock and organ malfunction may ensue, possibly leading to death. In heat stroke, the skin is likely to be red and hot to the touch, but dry; sweating might be absent. Once the body core hits 105 degrees or more, thermoregulation breaks down and the body’s ability to use sweating as a natural temperature regulator fails. In heat stroke, the body core can rise to 110 degrees Fahrenheit or more.

In some circumstances, the patient’s skin may actually seem cool. It is important to realize that it is the body core temperature that is elevated. A person in shock may feel “cold and clammy” to the touch. You could be misled by this finding, but simply taking a reading with a thermometer will reveal the patient’s true status.

heat stroke treatment basics, but avoid fluids in someone with altered mental status

When overheated patients are no longer able to cool themselves, it is up to their rescuers to do the job. If hyperthermia is suspected, the victim should immediately:

Be removed from the heat source (for example, out of the sun).
Have their clothing removed.
Be drenched with cool water (or ice, if available)
Have their legs elevated above the level of their heart (the shock position)
Be fanned or otherwise ventilated to help with heat evaporation
Have moist cold compresses placed in the neck, armpit and groin areas

Why the neck, armpit and groin? Major blood vessels pass close to the skin in these areas, and cold packs will more efficiently cool the body core. Recent studies by the military suggest that cold packs to feet and hands are also helpful.

Oral rehydration is useful to replace fluids lost, but only if the patient is awake and alert. If your patient has altered mental status, he or she might “swallow” the fluid into their airways; this causes damage to the lungs and puts you in worse shape than when you started.

Heat stroke is preventable in many cases. People that should know about hot weather, the Arizona department of health, recommends the following:

Drink at least 2 liters (about a half-gallon) of water per day if you are mostly indoors and 1 to 2 additional liters for every hour of outdoor time. Drink before you feel thirsty, and avoid alcohol and caffeine.
Wear lightweight, light-colored clothing and use a sun hat or an umbrella to deflect the sun’s rays.
Eat smaller, more frequent meals instead of large ones.
Avoid strenuous activity.
Stay indoors as much as possible.
Take regular breaks if you exert yourself on warm days.

In a heat wave, it’s important to check on the elderly, the very young, and the infirm regularly and often. These people have more difficulty seeking help, and you might just save a life if you’re vigilant. You can bet there’ll be more than one heat wave this summer, so know the warning signs and how to help those with hyperthermia.

Joe Alton MD